ISO 81400-4:2005

Wind turbines - Part 4: Design and specification of gearboxes

ISO 81400-4:2005 establishes the design and specification of gearboxes for wind turbines with power capacities ranging from 40 kW to 2MW. It is applicable to all such parallel-axis, one-stage epicyclic and combined one-stage epicyclic and parallel shaft enclosed gearboxes. Its provisions are based on field experience with wind turbines having the above power capacities and configurations; its guidelines can be applied to higher capacity wind turbines provided the specifications are appropriately modified to accommodate the characteristics of higher capacity wind turbines. Life requirements apply to wind turbines with a minimum design lifetime of 20 years.

Aérogénérateurs — Partie 4: Conception et spécifications relatives aux boîtes de vitesses

L'ISO 81400-4:2005 s'applique aux boîtes de vitesses pour aérogénérateurs, dont la puissance est comprise entre 40 kW et 2 MW. Elle s'applique à toutes les boîtes de vitesses sous carter, qu'elles soient à axes parallèles, épicycloïdales à une seule phase, ou bien qu'elles comprennent des combinaisons d'engrenages épicycloïdaux à une phase et à axes parallèles. Les dispositions de l'ISO 81400-4:2005 sont fondées sur l'expérience acquise sur le terrain avec des aérogénérateurs du type de ceux cités plus haut en termes de puissance et de configuration. Les lignes directrices présentées dans l'ISO 81400-4:2005 peuvent être appliquées à des aérogénérateurs de plus grande capacité, à condition que les spécifications soient modifiées en conséquence. Les exigences relatives à la durée de vie s'appliquent aux aérogénérateurs ayant une durée de vie théorique d'au moins 20 ans.

Vetrne elektrarne – 4. del: Oblikovanje in določitev gonil

General Information

• Status: Withdrawn
• Publication Date: 28-Sep-2005
• Withdrawal Date: 28-Sep-2005
• ICS: 21.200 - Gears
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: ISO/TC 60 - Gears
• Drafting Committee: ISO/TC 60 - Gears
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 05-Dec-2012
• Completion Date: 30-Oct-2025
• Ref Project: SIST ISO 81400-4:2006 - Wind turbines -- Part 4: Design and specification of gearboxes

Relations

• Corrected By: ISO 81400-4:2005/Cor 1:2005 - Wind turbines - Part 4: Design and specification of gearboxes - Technical Corrigendum 1
• Effective Date: 06-Jun-2022
• Revised: IEC 61400-4:2012 - Wind turbines - Part 4: Design requirements for wind turbine gearboxes
• Effective Date: 15-Apr-2008
• Parent: SIST ISO 81400-4:2006/TC1:2006 - ISO 81400-4:2005/Cor 1:2005
• Effective Date: 14-Aug-2008
• Parent: ISO 81400-4:2005/Cor 1:2005 - Wind turbines - Part 4: Design and specification of gearboxes - Technical Corrigendum 1
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 81400-4
First edition
2005-10-01
Wind turbines —
Part 4:
Design and specification of gearboxes
Aérogénérateurs —
Partie 4: Conception et spécifications des boîtes de vitesses

Reference number
©
ISO 2005
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ii © ISO 2005 – All rights reserved

Contents
Page
Foreword . iv
1 Scope . 1
2 Normative references. 1
3 Definitions and symbols. 2
4 Design specification . 7
5 Gearbox design and manufacturing requirements. 11
6 Lubrication . 28
7 Other important items. 33
Bibliography . 92
Annexes
A Wind turbine architecture. 35
B Wind turbine load description . 41
C Quality assurance. 49
D Operation and maintenance . 55
E Minimum purchaser and gearbox manufacturer ordering data . 57
F Lubrication selection and condition monitoring. 61
G General gear information. 77
H Determination of the application factor, K , from a given load spectrum
A
using the equivalent torque, T . 79
eq
I Bearing stress calculation . 83
Figures
1 3--stage parallel shaft gearbox . 20
2 3--stage planet/helical hybrid. 20
3 Bearing assembly . 21
Tables
1 Symbols . 3
2 Minimum basic rating life, L . 13
h10
3 Guide values for maximum contact stress for rolling element bearings at
Miner’s sum dynamic equivalent bearing load . 13
4 Bearing lubricant operating temperature for calculation of viscosity ratio,κ . 14
5 Temperature gradients for calculation of operating clearance . 15
6 Required gear accuracy . 17
7 Recommended gear tooth surface roughness . 17
8 Bearings for combined loads . 18
9 Bearings for pure radial load. 19
10 Bearings for pure axial loads . 19
11 Bearing selection matrix -- legend to symbols . 22
12 Bearing selection matrix for the low speed shaft/planet carrier . 22
13 Bearing selection matrix for the low speed intermediate shaft. 23
14 Bearing selection matrix for the high speed intermediate shaft . 24
15 Bearing selection matrix for the high speed shaft . 25
16 Bearing selection matrix for the planet wheel. 26
17 Lubricant cleanliness . 30
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 81400-4 was prepared by AWEA and AGMA (as ANSI/AGMA/AWEA 6006-A03) and was adopted, under
a special “fast-track procedure”, by Technical Committee ISO/TC 60, Gears, in parallel with its approval by the
ISO member bodies.
ISO 81400 is part of the IEC 61400 series.

iv © ISO 2005 – All rights reserved

Introduction
Theoperationandloadingofawindturbinespeedincreasinggearboxisunlikemostother
gear applications. The intent of this standard is to describe the differences. Much of the
informationisbasedonfieldexperience. Thisstandardisatoolwherebywindturbineand
gearbox manufacturers can communicate and understand each other’s needs in
developing a gearbox specification for wind turbine applications. The annexes present
informative discussion of various issues specific to wind turbine applications and gear
design.
A combined committee of the American Wind Energy Association (AWEA) and American
GearManufacturersAssociation(AGMA)membersrepresentinginternationalwindturbine
manufacturers, operators, researchers, consultants; and gear, bearing, plus lubricant
manufacturers were responsible for the drafting and development of this standard.
The committee first met in 1993 to develop AGMA/AWEA 921–A97, Recommended
PracticesforDesignandSpecificationofGearboxesforWindTurbineGeneratorSystems.
The AGMA Information Sheet was approved by the AGMA/AWEA Wind Turbine Gear
CommitteeonOctober25,1996andbytheAGMATechnicalDivisionExecutiveCommittee
on October 28, 1996. This standard superseded AGMA/AWEA 921–A97.
ThefirstdraftofANSI/AGMA/AWEA6006--A03wasmadeinMarch,2000. Itwasapproved
by the AGMA membership in October, 2003. It was approved as an American National
Standard (ANSI) on January 9, 2004.
ISO 81400--4:2005(E)
INTERNATIONAL STANDARD
AGMA 913--A98, Method for Specifying the
Geometry of Spur and Helical Gears
AGMA 925--A03, Effect of Lubrication on Gear
Wind turbines -- Part 4:
Surface Distress
AMS 2301, Aircraft quality steel cleanliness,
Design and
magnetic particle inspection procedure
ANSI Y12.3--1968, Letter symbols for quantities
specification of
used in mechanics of solids
ANSI/AGMA 1012--F90, Gear Nomenclature,
gearboxes
Definitions of Terms with Symbols
ANSI/AGMA 2101--D04, Fundamental Rating Fac-
torsandCalculationMethodsforInvoluteSpurand
Helical Gear Teeth
1 Scope
ANSI/AGMA6000--B96,SpecificationforMeasure-
ment of Linear Vibration on Gear Units
Thisstandardappliestogearboxesforwindturbines
ANSI/AGMA 6001--D97, Design and Selection of
withpowercapacitiesrangingfrom40kWto2MW. It Components for Enclosed Gear Drives
applies to all parallel axis, one stage epicyclic, and
ANSI/AGMA 6025--D98, Sound for Enclosed
combined one stage epicyclic and parallel shaft
Helical,Herringbone,andSpiralBevelGearDrives
enclosed gearboxes. The provisions made in this
ANSI/AGMA6110--F97,StandardforSpur,Helical,
standard are based on field experience with wind
Herringbone and Bevel Enclosed Drives
turbines having the above power capacities and
ANSI/AGMA 6123--A88, Design Manual for En-
configurations.
closed Epicyclic Metric Module Gear Drives
Guidelinesofthisstandardmaybeappliedtohigher
ANSI/AGMA9005--E02,IndustrialGearLubrication
capacity wind turbines provided the specifications
ASTMA534,Standardspecificationforcarburizing
are appropriately modified to accommodate the
steels for anti--friction bearings
characteristics of higher capacity wind turbines.
DetNorskeVeritasClassificationAS,Classification
Life requirements apply to wind turbines with a
Notes No. 41.2, Calculation of Gear Rating for
minimum design lifetime of 20 years.
Marine Transmissions, July 1993
DIN ISO 281 Bbl. 4:2003, Dynamische Tragzahl
und nominelle Lebensdauer -- Verfahren zur Ber-
2 Normativereferences
echnung der modifizierten Referenzlebensdauer
für allgemein belastete Wälzlager (Dynamic load
The following standards contain provisions which, ratings and life -- Method for calculation of the
modified reference rating life for generally loaded
throughreferenceinthistext,constituteprovisionsof
1)
rolling bearings)
thisstandard. Atthetimeofpublication,theeditions
indicated were valid. All standards are subject to
DIN743:2000,TragfähigkeitsberechnungvonWell-
revision, and parties to agreements based on this en und Achsen (Calculation of load capacity of
standardareencouragedtoinvestigatethepossibil- shafts and axles)
ity of applying the most recent editions of the
DIN 6885--2:1967, Drive Type Fastenings without
documents indicated below.
Taper Action; Parallel Keys, Keyways
AGMA 901--A92, A Rational Procedure for DIN 7190:2001, Interference fits -- Calculation and
Preliminary Design of Minimum Volume Gears design rules
1)
English translation available as ISO TC 4/SC 8 N254a
ISO 81400--4:2005 (E)
ISO 76:1987,Rollingbearings -- Static loadratings
3 Definitions and symbols
ISO 281:1990, Rolling bearings -- Dynamic load
3.0 Terms and definitions
rating and rating life
For the purposes of this document, the terms and
ISO R773:1969, Rectangular or square parallel
definitionsgivenin3.2through3.4andthefollowing
keysandtheircorrespondingkeyways(dimensions
apply, wherever applicable, conforming to ANSI/
in millimeters)
AGMA 1012--F90, and ANSI Y12.3--1968.
ISO 1328--1, Cylindrical Gears -- ISO System Of
3.1 Symbols
Accuracy -- Part 1: Definitions and Allowable
The symbols, terms and units used in this standard
Values of Deviations Relevant to Corresponding
are shown in table 1.
Flanks of Gear Teeth
NOTE: The symbols and terms contained in this
ISO4406:1999(SAEJ1165),Hydraulic fluidpower
document may vary from those used in other AGMA
-- Fluids -- Method for coding the level of standards. Usersofthisstandardshouldassurethem-
selvesthattheyareusingthesesymbolsandtermsin
contamination by solid particles
the manner indicated herein.
ISO 6336-- 1: 1996, Calculation of load capacity of
3.2 Wind turbine terms
spur and helical gears-- Part 1: Basic principles,
introduction and general influence factors activeyaw:A systemtorotatethenacellerelativeto
thechangingdirectionofthewind.Seepassiveyaw.
ISO 6336-- 2: 1996, Calculation of load capacity of
airfoil: Two dimensional cross section of a blade.
spur and helical gears-- Part 2: Calculation of
surface durability (pitting)
annual average wind speed: The time averaged,
mean, horizontal wind speed for one calendar year
ISO 6336-- 3: 1996, Calculation of load capacity of
at a particular site and a specified height.
spurandhelicalgears-- Part3:Calculation oftooth
annualaverageturbulenceintensity: Ameasure
bending strength
of the short--time and spatial variation of the inflow
ISO 6336--5: 1996, Calculation of load capacity of
wind speed about its long time average.
spurandhelicalgears--Part5:Strengthandquality
availability: Theratioofthenumberofhoursthata
of materials
turbinecouldoperatetothetotalnumberofhoursin
2)
that period, usually expressed as a percentage.
ISO/DIS 6336--6 , Calculation of load capacity of
Downtime due to faults or maintenance (scheduled
spur and helical gears -- Part 6: Calculation of
or otherwise) generally make up the unavailable
service life under variable load
time.
ISO 8579--1:2002, Acceptance code for gears --
bedplate: In a modular system, the structure that
Part 1: Determination of airborne sound power
supports the drive train components and nacelle
levels emitted by gear units
cover. Also called a main frame.
ISO 8579--2:1993, Acceptance code for gears --
blade: The component of the rotor that converts
Part 2: Determination of mechanical vibration of
wind energy into rotation of the rotor shaft.
gear units during acceptance testing
brake: A device capable of stopping rotation of the
rotor or reducing its speed.
ISO/TR 13593:1999, Enclosed gear drives for
industrial applications
certification: Procedurebywhichathirdpartygives
writtenassurancethataproduct,processorservice
ISO/TR13989--1:2000,Calculationofscuffingload
conforms to specified requirements, also known as
capacity of cylindrical, bevel and hypoid gears --
conformity assessment.
Part 1: Flash temperature method
certification standard: Standard that has specific
ISO 14104:1995, Gears -- Surface temper etch
rules for procedures and management to carry out
inspection after grinding
certification of conformity.
ISO/TR14179--1:2001,Gears--Thermalcapacity--
control system: A system that monitors the wind
Part 1: Rating gear drives with thermal equilibrium
turbine and its environment and adjusts the wind
at 95°C sump temperature turbine to keep it within operating limits.
____________________
2)
Presently at the development stage.
2 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
Table1 -- Symbols
Where
Symbol Term Units firstused
C Basic dynamic load rating N Eq 1
C Basic static load rating N 5.1.3.1
f Mesh misalignment -- -- 5.1.1.3
ma
K Ratio between the equivalent and the nominal torque -- -- 5.1.1.5
A
K Load distribution factor -- -- 5.1.1.2
Hβ
K Ratio of maximum contact pressure to contact pressure for line -- -- Eq 4
lc
contact without misalignment
K Ratio of maximum contact pressure with misalignment to maximum -- -- Eq 4
m
contact pressure without misalignment
K Dynamic factor -- -- 5.1.1.1
v
k Load sharing factor for the maximum loaded roller -- -- Eq 2
L Combined advanced rating life hours 5.1.3.2.3
adv
L Advanced rating life on the ith load level hours Eq 5
adv,i
L Basic rating life hours Eq 1
h10
L Effective roller length mm Eq 3
we
L Combined nominal reference rating life hours 5.1.3.2.3
10r
n Rotational speed rpm Eq 1
P Dynamic equivalent bearing load N Eq 1
P Equivalent static bearing load N 5.1.3.1
o
P Rated power of wind turbine kW Eq 6
t
p Exponent in bearing life equation -- -- Eq 1
p Contact pressure for line contact MPa Eq 3
line
p Maximum contact stress MPa Table 3
max
Q Single roller maximum load for a clearance free bearing N Eq 2
Q Recommended oil quantity liters Eq 6
ty
q Time share on the ith load level -- -- Eq 5
i
Ra Roughness average mm 5.2.8.2
Rz Mean peak--to--valley height mm 5.2.8.2
S Safety factor for bending strength -- -- 5.1.1.4
F
S Safety factor for pitting resistance -- -- 5.1.1.4
H
Y Stress cycle factor for bending strength -- -- 5.1.1.4
N
Y Life factor for bending -- -- 5.1.1.5
NT
Z Total number of rolling elements -- -- Eq 2
Z Stress cycle factor for pitting resistance -- -- 5.1.1.4
N
Z Life factor for pitting resistance -- -- 5.1.1.5
NT
α Nominal contact angle of the bearing degrees Eq 2
Σρ Curvature sum for line contact -- -- Eq 3
line
κ Viscosity ratio -- -- 5.1.3.3
cut--in wind speed: The minimum wind speed at dampedyaw: A deviceused toslow yaw motions.
hub height at which the control system calls for the
designlife: Theperiodofrealtimethatthesystem
turbine to produce power.
is expected to continue functioning. Includes
operating, idling and stopped time.
cut--outwindspeed: Themaximumwindspeedat
hub height at which the control system calls for the downwind turbine: A HAWT where the wind
turbine to produce power. passes the tower before the rotor.
ISO 81400--4:2005(E)
dynamicequivalentbearingload: Ahypothetical idling: Operating condition where the rotor is
load, constant in magnitude and direction, acting rotating and the generator is not producing power.
radially on radial bearings or axially on thrust
input or mechanical power: The mechanical
bearings, which if applied, would have the same
power measured at the gearbox low speed shaft or
influenceonbearinglifeastheactualloadstowhich
the wind turbine rotor shaft.
the bearing is subjected.
inputshaft: See rotor shaft.
emergency shutdown: A rapid shutdown of the
integratedsystem: Asystemarchitectureinwhich
wind turbine triggered by the control system, a
thegearbox housingsupports therotor directly,and
protection system or manual intervention.
in some cases, the generator(s) and other
extreme load: The extreme load is that load from
components. See modular system.
any source, either operating or non--operating, that
lock: The use of a mechanical device to prevent
is the largest single load that the gearbox will see
movement of the rotor or yaw drive.
during its design life beyond which the gearbox no
mainframe: See bedplate.
longer satisfies the design requirements. This load
can be either forces, moments, torques, or a
mainshaft: See rotor shaft.
combinationofthethree. Thisload,suppliedbythe
maximum operating load: The maximum operat-
wind turbine manufacturer, includes all partial load
ing load is the highest load in the load spectrum.
safety factors.
maximumpower: Thehighestlevelofnetelectrical
extremetorque: Theextremetorqueisthattorque
power delivered by a wind turbine in normal opera-
fromanysourcethatisthelargestsingletorquethat
tion.
the gearbox will see during its design life beyond
which the gearbox no longer satisfies the design
Miner’s sum dynamic equivalent bearing load:
requirements. The dynamic equivalent bearing load obtained by
combining loads and speeds in a wind spectrum
extreme wind speed: The highest short--term
using Miner’s rule.
average wind speed that is likely to be experienced
modular system: A system architecture in which
by the wind turbine during its service lifetime. It is
therotorshaftassembly,gearbox,generator(s)and,
typically based on statistical estimates of the long
possibly, a yaw drive, are separate components
term behavior of the wind speed.
mounted to a common main frame. See integrated
feathering: In a variable pitch HAWT, the action of
system.
pitching the blades to a minimum power production
motoring: Operatingconditionwherethegenerator
position.
is consuming power.
fixed pitch rotor: A rotor with blades that do not
nacelle: The structure that contains the drive train
changepitchduringoperation.Thepitchangleofthe
andothercomponentslocatedatthetopofaHAWT.
rotor blades may be changed manually for site
nacellecover: Thehousingthatcoversthenacelle.
specific or seasonal wind spectrum changes.
nominal speed: The gearbox low speed shaft
freeyaw: See passive yaw.
speed at which mechanical power is defined.
HAWT: Horizontal axis wind turbine. The rotational
non--rotating: Operating conditionwhere therotor
axis of the rotor is approximately parallel to the
is not rotating.
horizon.
normalshutdown: Transitionaloperatingcondition
horizontal axis: The axis of rotor rotation is
wheretherotordeceleratesfromoperatingspeedto
approximately parallel to the horizon.
standstill or idling and the generator ceases to
generate power.
hubheight: ForaHAWT,theheighttothecenterof
the rotor.
operationalwindspeedrange: Therangeofwind
speeds between the cut--in and the cut--out speed.
hub: The structure that attaches the blades to the
rotor shaft. outputshaft: See high speed shaft.
4 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
parked: Operating condition where the rotor is not upwind turbine: A HAWT where the wind passes
rotating because the parking brake is applied. the rotor before the tower.
variable pitchrotor:Arotorwhosebladepitchcan
parkingbrake: Adevicecapableofpreventingrotor
be varied during operation. The pitch angle may be
rotation.
activelycontrolledtooptimize powerorlimitloadsin
passive yaw: The forces of the wind are used to
response to the conditions.
alignthenacelle(rotordisk)relativetothechanging
variable speed: Rotor shaft torque limiting is
direction of the wind. See active yaw.
accomplished by using high voltage electronic
pitch: Theangularpositionoftherotorbladesabout
components andspecialgenerator designs toallow
their long axis.
a wide range of rotor speeds. This method utilizes
changes in inertial energy in the rotor to absorb the
pitchcontrol: Rotorshafttorquelimitingisaccom-
effect of wind gusts.
plished by actively adjusting the pitch.
VAWT: Verticalaxiswindturbine. Therotationalaxis
preventive maintenance: Scheduled work in-
of the rotor is approximately perpendicular to the
tended to prevent failure or unscheduled repairs.
horizon. This kindof turbineis beyondthescopeof
this standard.
rated power: The continuous electrical power
outputassignedbytheWTGSmanufacturerthatthe
windturbinegeneratorsystem(WTGS):Asystem
wind turbine is designed to achieve under normal
that converts the kinetic energy of the wind into
operating conditions at rated wind speed.
electrical power.
ratedwindspeed: The specified wind speed,
wind turbine manufacturer: Entity that designs,
assigned by the WTGS manufacturer, at which the
manufactures and warrants wind turbines.
rated power is produced.
wind turbine operator: Entity that operates and
rotor: The hub/blade assembly.
maintains wind turbines.
rotor bearing(s): The bearing(s) that supports the yaw: Rotation of a HAWT’s nacelle about the long
rotor shaft. axis of its tower. Usedtoorientatethenacelle(rotor
disk) with respect to the prevailing wind.
rotor diameter (horizontal axis): Diameter of the
yawbearing:Thebearingsystemthatsupportsthe
disk swept by the rotation of the blades.
nacelle in a HAWT. It permits the nacelle to rotate
rotor shaft: The shaft that supports the rotor and
about the tower axis.
transmitstherotortorquetothegearbox. Alsocalled
yaw drive: The system of components used to
the main shaft.
cause yaw motion.
rotor speed: The rotational speed of the wind
3.3 Gearboxterms
turbinerotoraboutitsaxis,inrevolutionsperminute.
alloysteel: Steelcontainingsignificantquantitiesof
stall control: Rotor shaft torque limiting is accom-
alloyingelementssuchasnickel,chrome,ormolyb-
plished by aerodynamic design (airfoil selection,
denumtoimproveitspropertiessuchashardenabil-
blade taper, blade twist, blade pitch, rotor speed).
ity or toughness.
standstill: See non--rotating.
ambient temperature: The dry bulb air tempera-
ture within the immediate vicinity of the gearbox.
startup: Transitional condition where the rotor
accelerates from standstill or idling to operating
annulus gear: Gear wheel with teeth on the inner
speed and the generator begins to generatepower.
surfaceofacylinder.Alsoknownasaninternalgear.
tower: The structure that supports the nacelle in a
aspectratio: Theratioofthepinionfacewidthtothe
HAWT.
pinion operating pitch diameter.
turbulence intensity: A statistical measure of the bearing basic rating life: The life where adjust-
variationinthewindspeed. Theratioofthestandard mentfactorsforreliability,materialandenvironment
deviationofthewindspeedtothemeanwindspeed. are taken as unity (1.0).
ISO 81400--4:2005(E)
bearing manufacturer: Entity that designs, helical gear: A gear with teeth that are inclined to
the gear axis like a helical screw.
manufactures and warrants bearings for wind tur-
bine gearboxes.
helix modification: A manufacturing modification
ofapinionorgearobtainedbychangingtheshapeof
bulk oil: The oil that is most representative of the
the tooth flank along the face width.
overall physical condition of the lubricant within the
high speed shaft: The highest speed shaft in a
lubrication system. With splash lubricated gear-
gearbox that drives the generator.
boxes, the location of this lubricant is at or near the
midpointoftheoilsumplevelshortlyafterthedriveis
housing: The enclosure that contains the gearbox
shutdownatoperatingtemperature. Withpressure
components such as gears, shafts, bearings and
fedlubricationsystems,thisisrepresentedbytheoil
associated components.
within the pressure line between the oil pump and
inner ring: In a bearing, the material between the
filter assembly during system operation.
inside dimension of the roller/ball and the outside
carburizing:Aheattreatmentprocesswheregears diameter of the part the bearing is mounted on.
areheatedinacarbonrichatmosphere(usuallygas
involute profile modification: A manufacturing
carburizing) that causes carbon to diffuse into the
modification of a pinion or gear where a small
surface layers of the gear teeth. The gears are
variable amount of material is removed along the
hardened by either quenching from the carburizing
tooth profile in the root to tip direction.
temperature or they are cooled, reheated and
low speed shaft: The lowest speed shaft in a
quenched. The carburizing and hardening is
gearbox. See rotor shaft.
followedbytemperingwherethegearsarereheated
to a relatively low temperature and slowly cooled.
lubricant manufacturer: Entity that designs,
manufactures and warrants lubricants for wind
coupling: Adevicethatconnectstworotatingshafts
turbine gearboxes.
totransmitpower,accommodatemisalignment,and
compensate for axial movement.
module: The ratio of the pitch diameter in millime-
ters to the number of teeth in a gear.
double helical gear: Gear wheel with both right--
nitriding: Heattreatmentprocesswheregearsare
handandleft--handhelices. Theteethareseparated
heated in a nitrogen atmosphere that causes nitro-
by a gap between the helices.
gen to diffuse into surface layers of gear teeth and
epicyclic: Geararrangementconsistingofmultiple
form hard nitrides. Distortion is small, because ni-
parallel axis gears including a sun pinion, several
triding is done at low temperatures and there is no
planetsthatmeshwiththesun,planetcarrier,andan
quench.
annulus gear that meshes with the planets.
outer ring: In a bearing, the material between the
gear: Of two gears in a gearset, the one with the
outside dimension of the roller/ball and the bore of
largernumberofteethisthegear.Alsoknownasthe
the part the bearing is mounted within.
wheel. See pinion.
parallel shaft: A gear arrangement where the
pinion and gear mesh on parallel axes.
gearbox: A complete assembly of gears, shafts,
bearings, housing, seals, lubrication system and
pinion: Oftwogearsinagearset,theonewithfewer
associated components.
number of teeth is the pinion. See gear.
gearbox manufacturer: Entity that designs, planetary: An epicyclic gear arrangement where
manufactures and warrants gearboxes for wind
the annulus is fixed, the planets rotate about their
turbines.
own axes, and the planet carrier rotates.
gear ratio: The ratio of the larger to the smaller power take--off (PTO): Additional output shaft for
number of teeth in a pair of gears.
driving auxiliary equipment, such as oil pumps.
gearset: Apinionandgearthatareintendedtorun profile shift: A modification of a gear where the
together. tooth profile is radially shifted.
protuberance cutter: A tool for cutting gear teeth
grinding notch: A discontinuity produced by a
that cuts a relief in the profile of the gear teeth to
grinding tool between the start of active profile and
tooth root that increases the tooth root stress. avoid grinding notches.
6 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
purchaser:Entitythatissuespurchasecontractsfor
4 Designspecification
wind turbine gearboxes.
4.1 Introduction
rimthickness: Theradialdistancefromtherootsof
Thisclauseprovidestheminimumrequiredinforma-
the teeth to the inner diameter of the rim or to the
tionforthespecificationofwindturbinegearboxes. It
boreonanexternalgear,andtotheoutsidediameter
is important for the purchaser to identify what is
on an internal gear.
expected of the gearbox manufacturer. A thorough
specification is the method by which this is done.
splitpowerpath: Ageararrangementconsistingof
The scope of the specification may range from only
multiple parallel axis gears. The arrangement is
performance and life requirements to detailed de-
analogous to epicyclic gears except there is no
signandmethodofcalculationrequirements. Ifwind
annulus gear.
turbine certification is required, the purchaser shall
spur gear: Gear with teeth that are parallel to the
clearlyspecifyallcertificationdocumentsrelevantto
gear axis.
the gearbox. The specification should contain the
information noted in annex E.
star: An epicyclic gear arrangement where the
annulusrotates,theplanets(stars)rotateabouttheir 4.2 Specificationintroduction
own axes, and the planet carrier is fixed.
An introduction shall be provided that identifies the
intent of the procurement specification. This shall
throughhardening: Heattreatmentprocesswhere
include a description of the type of wind turbine, its
gear blanks are austenitized, rapidly quenched to
basic modes of operation, the application of the
obtain a predominantly martensitic microstructure,
gearboxinthewindturbine,andadescriptionofthe
and tempered. Gear teeth are machined after
interfaces to the gearbox such as generator, rotor,
through hardening to avoid distortion.
bedplate, torque arm, lubricant system and
NOTE: Throughhardeningdoesnotimplythatthepart
accessories.
hasequivalent hardnessthroughouttheentirecross--
4.3 Gearboxconfiguration
section.
4.3.1 Configuration
torquearm: Astructuralcomponentthatattachesto
The general configuration of the gearbox shall be
the housing of a shaft mounted gearbox and
specified. This may include: the type of mounting;
prevents rotation of the gearbox about the rotor
the type of gearing; the gear arrangement; the
shaft.
numberofhighspeedshafts;thelocationandtypeof
wheel: Of two gears in a gearset, the one with the
power take--off gears (PTO); and the method of
larger number of teeth is the wheel. Also known as
lubrication.
the gear.
All requirements for the geometric configuration of
3.4 Filtrationterms thegearboxshallbespecified. Thismayinclude:the
overalllength,width,orheight;thedistancebetween
cleanlinesslevel: Thecleanlinesslevelasdefined
shaft centers; length of shaft extensions; angle of
by ISO 4406 is a code system used to quantify the
shaft tilt or offset; gear housing split plane; the
number of particles of a certain size in a given
maximum weight, or other features.
volume of oil. See annex F.
A detailed description of all components interfaced
filter: A device for removing solid particles from a
to the gearbox shall be provided. Each interface
liquid stream, typically by means of porous media.
shall be detailed for mounting, support and loading.
4.3.2Rotorspeed
inline filter: A filter installed in the main oil
circulation systemthat supplies gears andbearings
Therotorspeed,orspeedrange,shallbespecified.
with oil.
This shall include expected speed during power
productionandidlingmode. Thedirectionofrotation
offline filter: A filtration device independent of the
for each of these situations shall be specified.
main lubrication system, typically with a separate
4.3.3 Gearratio
pump, that operates continuously to improve oil
cleanliness. Also called bypass filter, kidney loop The overall gear ratio and its tolerance shall be
filter, or side stream filter. specified for the drive gears and any PTO gears.
ISO 81400--4:2005(E)
The overall gear ratio of the gearbox is set by the It shall be clearly stated as to which portion of the
requirements for rotor speed and generator speed. turbine lifetime the spectrum refers.
However, if there is more than one stage of gears,
For variable speed wind turbines, it may be neces-
thegearbox manufacturer can selectgear ratios for
sary to separate each torque bin into severalspeed
eachstagetomaximizeloadcapacity andminimize
bins.
weight (see AGMA 901--A92).
Specifiedtorquelevelofeachbinshallrepresentthe
4.4 Loading
highest level of torque represented in that bin. To
avoid excessive conservatism, sufficient quantity of
4.4.1 Descriptionofloads
bins(atleast40)shallbeused. Binwidthneednotbe
Itistheresponsibilityofthewindturbinemanufactur-
uniform, and, in fact, finer resolution at the highest
ertoprovideallloadsappliedtothegearboxtoallow
torque bins is preferred. The load spectrum shall
adequate evaluation of the design life requirements
also contain one bin that accounts for idling and
for all gears, bearings, shafts and the housing (see
stoppedtime. Theloadspectrumtotaltimewillthen
annex B). The details of this load description are
match the design life of the turbine.
presented in the following sections.
The torque spectrum shall include all fatigue loads,
including all external transient loads such as brake
The loads should be thoroughly detailed in a load
loads,ifapplicable. Ifmorethanasingledrivenload,
description document. This document should
such as multiple generators, pump drives, or other
include:
PTO’s exist, the torque spectrum for each driven
-- torque--frequency histogram including all
load shall be defined.
operating loads;
4.4.2.2Extremetorqueloads
-- transient loads described as annotated time
Extremetorqueshallbespecifiedbythewindturbine
series. RefertosectionB.5.2.2andfigureB.2 for
a sample of an annotated brake event; manufacturer:
-- torque level;
-- torque--speed relationships; and
-- number of occurrences;
-- other structural loads described in fatigue--
basedcyclecountsatpertinentinterfaces. These
-- source, such as rotor, generator or brake.
loads can be presented as a representative time
Extreme loads shall not be included in the load
series of the loads or the results of a Rainflow
spectrum.
Count [1] with mean value, amplitude (peak--to--
peak), and frequency of occurrence.
4.4.3Structuralloads
The purchaser shall indicate in the loads document
4.4.3.1Non--torqueloadsources
thepartialsafetyfactorsandloaduncertaintyfactors
In the case that the wind turbine rotor operation
usedinderivingtheloads. Anyadditionalmultipliers
imparts non--torqueloads tothegearbox low speed
to be applied to the loads shall be explicitly stated.
shaft, these loads shall be sufficiently described in
The source and rationale for the use of the safety
the specification. Such loads may occur in any
factors or multipliers or both shall be described or
operating mode of the wind turbine including idling
sufficiently referenced.
mode or when the turbine is parked. In modular
4.4.2Torqueloads arrangementstheshaftsare subjectedto loadsthat
need to be tolerated and transferred to the base
4.4.2.1Fatigue
mount (see A.5). Also, the generator, brake and
other interfaced components can affect reaction
The low speed shaft torque spectrum shall be
loads on the gearbox and shafts. Such loads may
specified in bins with:
occur in any operating mode of the wind turbine
-- torque level;
includingidlingmodeor whentheturbineis parked.
These loads shall be sufficiently described in the
-- cycles or revolutions per torque level;
specification. Stiffness in all loading directions of
-- nominal speed for design;
compliant supports, such as elastomeric bushings,
-- idling speed. shall be specified by the purchaser.
8 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
4.4.3.2Structuralfatigueloads 4.4.5 Dynamicloading
The loads specified by the purchaser shall include
For each type of external load applied to the
effects from the system’s dynamics. Depending on
gearbox, fatigue loads shall be defined at the
the layout of the drive train and nacelle, the
interface in a prescribed coordinate system as
purchaser should quantify static and dynamic rela-
moments and forces in three directions.
tivedisplacementsofthedifferentsubsystems. The
Loads for each axis shall be defined in a spectrum,
purchaser shouldalsospecify absolutemovements
specified by bins, with:
andaccelerationsofthegearbox. Implementationof
this dynamic analysis is a joint effort between
-- moment level;
purchaserandgearboxmanufacturer. Toenablethe
-- force level; purchaser to perform the dynamic analysis during
the development process, the gearbox manufactur-
-- cyclesperrevolutionpermoment/forcelevel.
er should supply general gearbox data, such as
Multi--axisloadsshallbeprovidedinsuchawaythat center of gravity, stiffness, inertia, damping, and
thephaserelationshipispreserved. Theinterpreta- clearances.
tionanduseofdatashallbeajointeffortbetweenthe
4.5Certification
wind turbine manufacturer and the gearbox
Wind turbines are usually certified to facilitate due
manufacturer.
diligence efforts and insurance requirements. All
4.4.3.3Structuralextremeloads
requirements for certification shall be described in
the specification, including:
For each type of external loading to the gearbox,
– name of classification society;
extreme loads shall be defined at the interface, in a
prescribed coordinate system, with moments and – standard or certification document name,
number, and revision level;
forces in three directions.
– applicable section or paragraphs;
4.4.4 Idling,parkingandtransientoperation
– any exceptions to the above documents.
Featuressuchasdurationandfrequencyofspeeds
Safety factors in excess of certification standard
and loads, method of lubrication, and temperature
requirementsshallbespecified. Itistheresponsibil-
rangesduringidling,parkingandtransientoperation
ityofthepurchaserthatthepurchasespecificationis
shall be specified.
consistent with the relevant certification standards.
4.4.4.1 Idling
4.6 Operatingenvironment
Theexpectedoperatingenvironmentofthegearbox
Rotors shouldbeallowed toidle whenever possible
shall be specified. As a minimum this shallinclude:
to avoid false brinelling, fretting corrosion, and
theambienttemperaturerange,airtemperatureand
corrosionongearteeth, splines,bearingrollersand
air velocity across the gearbox, maximum relative
bearing raceways.
humidity, extent of exposure to direct sunlight,
4.4.4.2 Parking
precipitationandairborneparticulates.SeeannexE
for additional information on this subject.
Parking should be minimized to avoid false brinel-
4.7 Controlandmonitoring
ling, fretting corrosion, and corrosion on gear teeth,
splines, bearing rollers, and bearing raceways.
Requirements for monitoring and control sensors
Dynamic loads on a parked wind turbine shall be
associatedwiththegearboxshallbespecified. This
specifiedindetail,forexample,byanannotatedtime
may include: lubricant level, temperature, pressure
series.
sensors, vibration sensors, filter bypass sensors,
particulate accumulation sensors, or others.
4.4.4.3 Transientoperations
4.8 Qualificationtesting
Transient load events such as braking, cut--in,
4.8.1 Prototypetests
cut--out,generatorshift, andbladepitchoperations,
shall be specified in detail, for example, by an Typeandconditionsofanyqualificationtestingshall
annotated time series. be specified. These tests shall be performed on a
ISO 81400--4:2005(E)
prototype unit of the gearbox with gears and tion. Atthispoint,theroughnessprofileofgearsand
housings previously measured and recorded. Test bearings is still dominated by the texture generated
duration shall be agreed to between the purchaser inthefinishingprocess. Highlocalcontactstressat
and gearbox manufacturer. The test shall observe roughness peaks may cause micropitting, surface
the development of contact pattern with rising load distress, scuffing or other irreversible wear pro-
(documented at defined steps). The test shall be cesses. The surface finish achieved during the
performed up to the design load for the helix and manufacturing process significantly influences
profile modifications. The test results shall be well these risks. Methods like super--finishing, surface
documentedbyphotosandshallbecomparedtothe plating or run--in at controlled power levels may be
design calculations in order to verify the calculation required to reduce these risks.
model. In addition, bearing and oil temperatures
The wind turbine manufacturer and the gearbox
should be reported. Typical test length should be a
manufacturershallmutuallyagreeamongtheabove
function of the time required for system tempera-
methods with consideration of the actual geometry,
tures to stabilize.
manufacturing processes, stress level, slide ratio,
λ--ratio, and operating modes of the wind turbine.
In addition to the contact pattern development and
The suitability of the selected means shall be
thermal capacity test, an instrumented overload,
documented, for example, by prototype testing.
long duration prototype qualification test may be
When possible, the wind turbine operator should
required. Test conditions for such a test are to be
also agree on the above methods.
agreed to between the purchaser and the gearbox
manufacturer at the time of purchase.
Uncertainties of the wind make it difficult to achieve
properrun--inconditionsduringfieldcommissioning,
4.8.2 Soundemissiontesting
therefore a run--in will typically be performed at the
Acceptance tests for verification of the sound
factory. Operating and load conditions of a run--in
emissions from the gearbox shall be specified.
shallbeselectedwithcaretoavoidinitialdamageto
Testing conditions for the acceptance measure-
gears and bearings. Refer to table 17 for oil
ments shall also be specified. ANSI/AGMA
cleanliness at the run--in test.
6025--D98(soundpressuremeasurement)andISO
The wind turbine manufacturer and the gearbox
8579--1 (sound power measurement) are two pos-
manufacturershallmutuallydetermineandagreeto
sible methods for measurement. The specification
startup,commissioning,operatingandmaintenance
of test conditions may include: speed, torque,
procedures designed to avoid gearbox damage
temperature, type of lubricant, direction of rotation,
during initial turbine startup. The wind turbine
mounting of gearbox, type of drive motor, type of
manufacturer shall include these procedures in the
measurement device, range of frequencies, and
startup,commissioning,operatingandmaintenance
others. Inaddition,itmaybedesirabletospecifythe
documentation. The wind turbine operator shall
tonal character of the sound emission.
follow the procedures as outlined in the operating
and maintenance documentation.
4.8.3 Vibrationtesting
4.10 Transportandconstruction
Acceptance tests for verification of the vibration of
thegearboxshallbespecified. Testingconditionsfor
There are many possible sources of damage to the
the acceptance measurements shall also be
gearboxduringtransport,storage,andconstruction.
specified. ANSI/AGMA 6000--B96and ISO 8579--2
Of particular concern are contamination, corrosion,
are two possible methods for measurement. The
frettingcorrosionandfalsebrinelling. Itshallbethe
specification of test conditions may include: speed,
responsibility of the gear manufacturer to ensure
torque, tempe
...

SLOVENSKI STANDARD
01-december-2006
9HWUQHHOHNWUDUQH±GHO2EOLNRYDQMHLQGRORþLWHYJRQLO
Wind turbines -- Part 4: Design and specification of gearboxes
Aérogénérateurs -- Partie 4: Conception et spécifications des boîtes de vitesses
Ta slovenski standard je istoveten z: ISO 81400-4:2005
ICS:
21.200 Gonila Gears
27.180 Sistemi turbin na veter in Wind turbine systems and
drugi alternativni viri energije other alternative sources of
energy
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 81400-4
First edition
2005-10-01
Wind turbines —
Part 4:
Design and specification of gearboxes
Aérogénérateurs —
Partie 4: Conception et spécifications des boîtes de vitesses

Reference number
©
ISO 2005
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©  ISO 2005
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
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Published in Switzerland
ii © ISO 2005 – All rights reserved

Contents
Page
Foreword . iv
1 Scope . 1
2 Normative references. 1
3 Definitions and symbols. 2
4 Design specification . 7
5 Gearbox design and manufacturing requirements. 11
6 Lubrication . 28
7 Other important items. 33
Bibliography . 92
Annexes
A Wind turbine architecture. 35
B Wind turbine load description . 41
C Quality assurance. 49
D Operation and maintenance . 55
E Minimum purchaser and gearbox manufacturer ordering data . 57
F Lubrication selection and condition monitoring. 61
G General gear information. 77
H Determination of the application factor, K , from a given load spectrum
A
using the equivalent torque, T . 79
eq
I Bearing stress calculation . 83
Figures
1 3--stage parallel shaft gearbox . 20
2 3--stage planet/helical hybrid. 20
3 Bearing assembly . 21
Tables
1 Symbols . 3
2 Minimum basic rating life, L . 13
h10
3 Guide values for maximum contact stress for rolling element bearings at
Miner’s sum dynamic equivalent bearing load . 13
4 Bearing lubricant operating temperature for calculation of viscosity ratio,κ . 14
5 Temperature gradients for calculation of operating clearance . 15
6 Required gear accuracy . 17
7 Recommended gear tooth surface roughness . 17
8 Bearings for combined loads . 18
9 Bearings for pure radial load. 19
10 Bearings for pure axial loads . 19
11 Bearing selection matrix -- legend to symbols . 22
12 Bearing selection matrix for the low speed shaft/planet carrier . 22
13 Bearing selection matrix for the low speed intermediate shaft. 23
14 Bearing selection matrix for the high speed intermediate shaft . 24
15 Bearing selection matrix for the high speed shaft . 25
16 Bearing selection matrix for the planet wheel. 26
17 Lubricant cleanliness . 30
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 81400-4 was prepared by AWEA and AGMA (as ANSI/AGMA/AWEA 6006-A03) and was adopted, under
a special “fast-track procedure”, by Technical Committee ISO/TC 60, Gears, in parallel with its approval by the
ISO member bodies.
ISO 81400 is part of the IEC 61400 series.

iv © ISO 2005 – All rights reserved

Introduction
Theoperationandloadingofawindturbinespeedincreasinggearboxisunlikemostother
gear applications. The intent of this standard is to describe the differences. Much of the
informationisbasedonfieldexperience. Thisstandardisatoolwherebywindturbineand
gearbox manufacturers can communicate and understand each other’s needs in
developing a gearbox specification for wind turbine applications. The annexes present
informative discussion of various issues specific to wind turbine applications and gear
design.
A combined committee of the American Wind Energy Association (AWEA) and American
GearManufacturersAssociation(AGMA)membersrepresentinginternationalwindturbine
manufacturers, operators, researchers, consultants; and gear, bearing, plus lubricant
manufacturers were responsible for the drafting and development of this standard.
The committee first met in 1993 to develop AGMA/AWEA 921–A97, Recommended
PracticesforDesignandSpecificationofGearboxesforWindTurbineGeneratorSystems.
The AGMA Information Sheet was approved by the AGMA/AWEA Wind Turbine Gear
CommitteeonOctober25,1996andbytheAGMATechnicalDivisionExecutiveCommittee
on October 28, 1996. This standard superseded AGMA/AWEA 921–A97.
ThefirstdraftofANSI/AGMA/AWEA6006--A03wasmadeinMarch,2000. Itwasapproved
by the AGMA membership in October, 2003. It was approved as an American National
Standard (ANSI) on January 9, 2004.
ISO 81400--4:2005(E)
INTERNATIONAL STANDARD
AGMA 913--A98, Method for Specifying the
Geometry of Spur and Helical Gears
AGMA 925--A03, Effect of Lubrication on Gear
Wind turbines -- Part 4:
Surface Distress
AMS 2301, Aircraft quality steel cleanliness,
Design and
magnetic particle inspection procedure
ANSI Y12.3--1968, Letter symbols for quantities
specification of
used in mechanics of solids
ANSI/AGMA 1012--F90, Gear Nomenclature,
gearboxes
Definitions of Terms with Symbols
ANSI/AGMA 2101--D04, Fundamental Rating Fac-
torsandCalculationMethodsforInvoluteSpurand
Helical Gear Teeth
1 Scope
ANSI/AGMA6000--B96,SpecificationforMeasure-
ment of Linear Vibration on Gear Units
Thisstandardappliestogearboxesforwindturbines
ANSI/AGMA 6001--D97, Design and Selection of
withpowercapacitiesrangingfrom40kWto2MW. It Components for Enclosed Gear Drives
applies to all parallel axis, one stage epicyclic, and
ANSI/AGMA 6025--D98, Sound for Enclosed
combined one stage epicyclic and parallel shaft
Helical,Herringbone,andSpiralBevelGearDrives
enclosed gearboxes. The provisions made in this
ANSI/AGMA6110--F97,StandardforSpur,Helical,
standard are based on field experience with wind
Herringbone and Bevel Enclosed Drives
turbines having the above power capacities and
ANSI/AGMA 6123--A88, Design Manual for En-
configurations.
closed Epicyclic Metric Module Gear Drives
Guidelinesofthisstandardmaybeappliedtohigher
ANSI/AGMA9005--E02,IndustrialGearLubrication
capacity wind turbines provided the specifications
ASTMA534,Standardspecificationforcarburizing
are appropriately modified to accommodate the
steels for anti--friction bearings
characteristics of higher capacity wind turbines.
DetNorskeVeritasClassificationAS,Classification
Life requirements apply to wind turbines with a
Notes No. 41.2, Calculation of Gear Rating for
minimum design lifetime of 20 years.
Marine Transmissions, July 1993
DIN ISO 281 Bbl. 4:2003, Dynamische Tragzahl
und nominelle Lebensdauer -- Verfahren zur Ber-
2 Normativereferences
echnung der modifizierten Referenzlebensdauer
für allgemein belastete Wälzlager (Dynamic load
The following standards contain provisions which, ratings and life -- Method for calculation of the
modified reference rating life for generally loaded
throughreferenceinthistext,constituteprovisionsof
1)
rolling bearings)
thisstandard. Atthetimeofpublication,theeditions
indicated were valid. All standards are subject to
DIN743:2000,TragfähigkeitsberechnungvonWell-
revision, and parties to agreements based on this en und Achsen (Calculation of load capacity of
standardareencouragedtoinvestigatethepossibil- shafts and axles)
ity of applying the most recent editions of the
DIN 6885--2:1967, Drive Type Fastenings without
documents indicated below.
Taper Action; Parallel Keys, Keyways
AGMA 901--A92, A Rational Procedure for DIN 7190:2001, Interference fits -- Calculation and
Preliminary Design of Minimum Volume Gears design rules
1)
English translation available as ISO TC 4/SC 8 N254a
ISO 81400--4:2005 (E)
ISO 76:1987,Rollingbearings -- Static loadratings
3 Definitions and symbols
ISO 281:1990, Rolling bearings -- Dynamic load
3.0 Terms and definitions
rating and rating life
For the purposes of this document, the terms and
ISO R773:1969, Rectangular or square parallel
definitionsgivenin3.2through3.4andthefollowing
keysandtheircorrespondingkeyways(dimensions
apply, wherever applicable, conforming to ANSI/
in millimeters)
AGMA 1012--F90, and ANSI Y12.3--1968.
ISO 1328--1, Cylindrical Gears -- ISO System Of
3.1 Symbols
Accuracy -- Part 1: Definitions and Allowable
The symbols, terms and units used in this standard
Values of Deviations Relevant to Corresponding
are shown in table 1.
Flanks of Gear Teeth
NOTE: The symbols and terms contained in this
ISO4406:1999(SAEJ1165),Hydraulic fluidpower
document may vary from those used in other AGMA
-- Fluids -- Method for coding the level of standards. Usersofthisstandardshouldassurethem-
selvesthattheyareusingthesesymbolsandtermsin
contamination by solid particles
the manner indicated herein.
ISO 6336-- 1: 1996, Calculation of load capacity of
3.2 Wind turbine terms
spur and helical gears-- Part 1: Basic principles,
introduction and general influence factors activeyaw:A systemtorotatethenacellerelativeto
thechangingdirectionofthewind.Seepassiveyaw.
ISO 6336-- 2: 1996, Calculation of load capacity of
airfoil: Two dimensional cross section of a blade.
spur and helical gears-- Part 2: Calculation of
surface durability (pitting)
annual average wind speed: The time averaged,
mean, horizontal wind speed for one calendar year
ISO 6336-- 3: 1996, Calculation of load capacity of
at a particular site and a specified height.
spurandhelicalgears-- Part3:Calculation oftooth
annualaverageturbulenceintensity: Ameasure
bending strength
of the short--time and spatial variation of the inflow
ISO 6336--5: 1996, Calculation of load capacity of
wind speed about its long time average.
spurandhelicalgears--Part5:Strengthandquality
availability: Theratioofthenumberofhoursthata
of materials
turbinecouldoperatetothetotalnumberofhoursin
2)
that period, usually expressed as a percentage.
ISO/DIS 6336--6 , Calculation of load capacity of
Downtime due to faults or maintenance (scheduled
spur and helical gears -- Part 6: Calculation of
or otherwise) generally make up the unavailable
service life under variable load
time.
ISO 8579--1:2002, Acceptance code for gears --
bedplate: In a modular system, the structure that
Part 1: Determination of airborne sound power
supports the drive train components and nacelle
levels emitted by gear units
cover. Also called a main frame.
ISO 8579--2:1993, Acceptance code for gears --
blade: The component of the rotor that converts
Part 2: Determination of mechanical vibration of
wind energy into rotation of the rotor shaft.
gear units during acceptance testing
brake: A device capable of stopping rotation of the
rotor or reducing its speed.
ISO/TR 13593:1999, Enclosed gear drives for
industrial applications
certification: Procedurebywhichathirdpartygives
writtenassurancethataproduct,processorservice
ISO/TR13989--1:2000,Calculationofscuffingload
conforms to specified requirements, also known as
capacity of cylindrical, bevel and hypoid gears --
conformity assessment.
Part 1: Flash temperature method
certification standard: Standard that has specific
ISO 14104:1995, Gears -- Surface temper etch
rules for procedures and management to carry out
inspection after grinding
certification of conformity.
ISO/TR14179--1:2001,Gears--Thermalcapacity--
control system: A system that monitors the wind
Part 1: Rating gear drives with thermal equilibrium
turbine and its environment and adjusts the wind
at 95°C sump temperature turbine to keep it within operating limits.
____________________
2)
Presently at the development stage.
2 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
Table1 -- Symbols
Where
Symbol Term Units firstused
C Basic dynamic load rating N Eq 1
C Basic static load rating N 5.1.3.1
f Mesh misalignment -- -- 5.1.1.3
ma
K Ratio between the equivalent and the nominal torque -- -- 5.1.1.5
A
K Load distribution factor -- -- 5.1.1.2
Hβ
K Ratio of maximum contact pressure to contact pressure for line -- -- Eq 4
lc
contact without misalignment
K Ratio of maximum contact pressure with misalignment to maximum -- -- Eq 4
m
contact pressure without misalignment
K Dynamic factor -- -- 5.1.1.1
v
k Load sharing factor for the maximum loaded roller -- -- Eq 2
L Combined advanced rating life hours 5.1.3.2.3
adv
L Advanced rating life on the ith load level hours Eq 5
adv,i
L Basic rating life hours Eq 1
h10
L Effective roller length mm Eq 3
we
L Combined nominal reference rating life hours 5.1.3.2.3
10r
n Rotational speed rpm Eq 1
P Dynamic equivalent bearing load N Eq 1
P Equivalent static bearing load N 5.1.3.1
o
P Rated power of wind turbine kW Eq 6
t
p Exponent in bearing life equation -- -- Eq 1
p Contact pressure for line contact MPa Eq 3
line
p Maximum contact stress MPa Table 3
max
Q Single roller maximum load for a clearance free bearing N Eq 2
Q Recommended oil quantity liters Eq 6
ty
q Time share on the ith load level -- -- Eq 5
i
Ra Roughness average mm 5.2.8.2
Rz Mean peak--to--valley height mm 5.2.8.2
S Safety factor for bending strength -- -- 5.1.1.4
F
S Safety factor for pitting resistance -- -- 5.1.1.4
H
Y Stress cycle factor for bending strength -- -- 5.1.1.4
N
Y Life factor for bending -- -- 5.1.1.5
NT
Z Total number of rolling elements -- -- Eq 2
Z Stress cycle factor for pitting resistance -- -- 5.1.1.4
N
Z Life factor for pitting resistance -- -- 5.1.1.5
NT
α Nominal contact angle of the bearing degrees Eq 2
Σρ Curvature sum for line contact -- -- Eq 3
line
κ Viscosity ratio -- -- 5.1.3.3
cut--in wind speed: The minimum wind speed at dampedyaw: A deviceused toslow yaw motions.
hub height at which the control system calls for the
designlife: Theperiodofrealtimethatthesystem
turbine to produce power.
is expected to continue functioning. Includes
operating, idling and stopped time.
cut--outwindspeed: Themaximumwindspeedat
hub height at which the control system calls for the downwind turbine: A HAWT where the wind
turbine to produce power. passes the tower before the rotor.
ISO 81400--4:2005(E)
dynamicequivalentbearingload: Ahypothetical idling: Operating condition where the rotor is
load, constant in magnitude and direction, acting rotating and the generator is not producing power.
radially on radial bearings or axially on thrust
input or mechanical power: The mechanical
bearings, which if applied, would have the same
power measured at the gearbox low speed shaft or
influenceonbearinglifeastheactualloadstowhich
the wind turbine rotor shaft.
the bearing is subjected.
inputshaft: See rotor shaft.
emergency shutdown: A rapid shutdown of the
integratedsystem: Asystemarchitectureinwhich
wind turbine triggered by the control system, a
thegearbox housingsupports therotor directly,and
protection system or manual intervention.
in some cases, the generator(s) and other
extreme load: The extreme load is that load from
components. See modular system.
any source, either operating or non--operating, that
lock: The use of a mechanical device to prevent
is the largest single load that the gearbox will see
movement of the rotor or yaw drive.
during its design life beyond which the gearbox no
mainframe: See bedplate.
longer satisfies the design requirements. This load
can be either forces, moments, torques, or a
mainshaft: See rotor shaft.
combinationofthethree. Thisload,suppliedbythe
maximum operating load: The maximum operat-
wind turbine manufacturer, includes all partial load
ing load is the highest load in the load spectrum.
safety factors.
maximumpower: Thehighestlevelofnetelectrical
extremetorque: Theextremetorqueisthattorque
power delivered by a wind turbine in normal opera-
fromanysourcethatisthelargestsingletorquethat
tion.
the gearbox will see during its design life beyond
which the gearbox no longer satisfies the design
Miner’s sum dynamic equivalent bearing load:
requirements. The dynamic equivalent bearing load obtained by
combining loads and speeds in a wind spectrum
extreme wind speed: The highest short--term
using Miner’s rule.
average wind speed that is likely to be experienced
modular system: A system architecture in which
by the wind turbine during its service lifetime. It is
therotorshaftassembly,gearbox,generator(s)and,
typically based on statistical estimates of the long
possibly, a yaw drive, are separate components
term behavior of the wind speed.
mounted to a common main frame. See integrated
feathering: In a variable pitch HAWT, the action of
system.
pitching the blades to a minimum power production
motoring: Operatingconditionwherethegenerator
position.
is consuming power.
fixed pitch rotor: A rotor with blades that do not
nacelle: The structure that contains the drive train
changepitchduringoperation.Thepitchangleofthe
andothercomponentslocatedatthetopofaHAWT.
rotor blades may be changed manually for site
nacellecover: Thehousingthatcoversthenacelle.
specific or seasonal wind spectrum changes.
nominal speed: The gearbox low speed shaft
freeyaw: See passive yaw.
speed at which mechanical power is defined.
HAWT: Horizontal axis wind turbine. The rotational
non--rotating: Operating conditionwhere therotor
axis of the rotor is approximately parallel to the
is not rotating.
horizon.
normalshutdown: Transitionaloperatingcondition
horizontal axis: The axis of rotor rotation is
wheretherotordeceleratesfromoperatingspeedto
approximately parallel to the horizon.
standstill or idling and the generator ceases to
generate power.
hubheight: ForaHAWT,theheighttothecenterof
the rotor.
operationalwindspeedrange: Therangeofwind
speeds between the cut--in and the cut--out speed.
hub: The structure that attaches the blades to the
rotor shaft. outputshaft: See high speed shaft.
4 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
parked: Operating condition where the rotor is not upwind turbine: A HAWT where the wind passes
rotating because the parking brake is applied. the rotor before the tower.
variable pitchrotor:Arotorwhosebladepitchcan
parkingbrake: Adevicecapableofpreventingrotor
be varied during operation. The pitch angle may be
rotation.
activelycontrolledtooptimize powerorlimitloadsin
passive yaw: The forces of the wind are used to
response to the conditions.
alignthenacelle(rotordisk)relativetothechanging
variable speed: Rotor shaft torque limiting is
direction of the wind. See active yaw.
accomplished by using high voltage electronic
pitch: Theangularpositionoftherotorbladesabout
components andspecialgenerator designs toallow
their long axis.
a wide range of rotor speeds. This method utilizes
changes in inertial energy in the rotor to absorb the
pitchcontrol: Rotorshafttorquelimitingisaccom-
effect of wind gusts.
plished by actively adjusting the pitch.
VAWT: Verticalaxiswindturbine. Therotationalaxis
preventive maintenance: Scheduled work in-
of the rotor is approximately perpendicular to the
tended to prevent failure or unscheduled repairs.
horizon. This kindof turbineis beyondthescopeof
this standard.
rated power: The continuous electrical power
outputassignedbytheWTGSmanufacturerthatthe
windturbinegeneratorsystem(WTGS):Asystem
wind turbine is designed to achieve under normal
that converts the kinetic energy of the wind into
operating conditions at rated wind speed.
electrical power.
ratedwindspeed: The specified wind speed,
wind turbine manufacturer: Entity that designs,
assigned by the WTGS manufacturer, at which the
manufactures and warrants wind turbines.
rated power is produced.
wind turbine operator: Entity that operates and
rotor: The hub/blade assembly.
maintains wind turbines.
rotor bearing(s): The bearing(s) that supports the yaw: Rotation of a HAWT’s nacelle about the long
rotor shaft. axis of its tower. Usedtoorientatethenacelle(rotor
disk) with respect to the prevailing wind.
rotor diameter (horizontal axis): Diameter of the
yawbearing:Thebearingsystemthatsupportsthe
disk swept by the rotation of the blades.
nacelle in a HAWT. It permits the nacelle to rotate
rotor shaft: The shaft that supports the rotor and
about the tower axis.
transmitstherotortorquetothegearbox. Alsocalled
yaw drive: The system of components used to
the main shaft.
cause yaw motion.
rotor speed: The rotational speed of the wind
3.3 Gearboxterms
turbinerotoraboutitsaxis,inrevolutionsperminute.
alloysteel: Steelcontainingsignificantquantitiesof
stall control: Rotor shaft torque limiting is accom-
alloyingelementssuchasnickel,chrome,ormolyb-
plished by aerodynamic design (airfoil selection,
denumtoimproveitspropertiessuchashardenabil-
blade taper, blade twist, blade pitch, rotor speed).
ity or toughness.
standstill: See non--rotating.
ambient temperature: The dry bulb air tempera-
ture within the immediate vicinity of the gearbox.
startup: Transitional condition where the rotor
accelerates from standstill or idling to operating
annulus gear: Gear wheel with teeth on the inner
speed and the generator begins to generatepower.
surfaceofacylinder.Alsoknownasaninternalgear.
tower: The structure that supports the nacelle in a
aspectratio: Theratioofthepinionfacewidthtothe
HAWT.
pinion operating pitch diameter.
turbulence intensity: A statistical measure of the bearing basic rating life: The life where adjust-
variationinthewindspeed. Theratioofthestandard mentfactorsforreliability,materialandenvironment
deviationofthewindspeedtothemeanwindspeed. are taken as unity (1.0).
ISO 81400--4:2005(E)
bearing manufacturer: Entity that designs, helical gear: A gear with teeth that are inclined to
the gear axis like a helical screw.
manufactures and warrants bearings for wind tur-
bine gearboxes.
helix modification: A manufacturing modification
ofapinionorgearobtainedbychangingtheshapeof
bulk oil: The oil that is most representative of the
the tooth flank along the face width.
overall physical condition of the lubricant within the
high speed shaft: The highest speed shaft in a
lubrication system. With splash lubricated gear-
gearbox that drives the generator.
boxes, the location of this lubricant is at or near the
midpointoftheoilsumplevelshortlyafterthedriveis
housing: The enclosure that contains the gearbox
shutdownatoperatingtemperature. Withpressure
components such as gears, shafts, bearings and
fedlubricationsystems,thisisrepresentedbytheoil
associated components.
within the pressure line between the oil pump and
inner ring: In a bearing, the material between the
filter assembly during system operation.
inside dimension of the roller/ball and the outside
carburizing:Aheattreatmentprocesswheregears diameter of the part the bearing is mounted on.
areheatedinacarbonrichatmosphere(usuallygas
involute profile modification: A manufacturing
carburizing) that causes carbon to diffuse into the
modification of a pinion or gear where a small
surface layers of the gear teeth. The gears are
variable amount of material is removed along the
hardened by either quenching from the carburizing
tooth profile in the root to tip direction.
temperature or they are cooled, reheated and
low speed shaft: The lowest speed shaft in a
quenched. The carburizing and hardening is
gearbox. See rotor shaft.
followedbytemperingwherethegearsarereheated
to a relatively low temperature and slowly cooled.
lubricant manufacturer: Entity that designs,
manufactures and warrants lubricants for wind
coupling: Adevicethatconnectstworotatingshafts
turbine gearboxes.
totransmitpower,accommodatemisalignment,and
compensate for axial movement.
module: The ratio of the pitch diameter in millime-
ters to the number of teeth in a gear.
double helical gear: Gear wheel with both right--
nitriding: Heattreatmentprocesswheregearsare
handandleft--handhelices. Theteethareseparated
heated in a nitrogen atmosphere that causes nitro-
by a gap between the helices.
gen to diffuse into surface layers of gear teeth and
epicyclic: Geararrangementconsistingofmultiple
form hard nitrides. Distortion is small, because ni-
parallel axis gears including a sun pinion, several
triding is done at low temperatures and there is no
planetsthatmeshwiththesun,planetcarrier,andan
quench.
annulus gear that meshes with the planets.
outer ring: In a bearing, the material between the
gear: Of two gears in a gearset, the one with the
outside dimension of the roller/ball and the bore of
largernumberofteethisthegear.Alsoknownasthe
the part the bearing is mounted within.
wheel. See pinion.
parallel shaft: A gear arrangement where the
pinion and gear mesh on parallel axes.
gearbox: A complete assembly of gears, shafts,
bearings, housing, seals, lubrication system and
pinion: Oftwogearsinagearset,theonewithfewer
associated components.
number of teeth is the pinion. See gear.
gearbox manufacturer: Entity that designs, planetary: An epicyclic gear arrangement where
manufactures and warrants gearboxes for wind
the annulus is fixed, the planets rotate about their
turbines.
own axes, and the planet carrier rotates.
gear ratio: The ratio of the larger to the smaller power take--off (PTO): Additional output shaft for
number of teeth in a pair of gears.
driving auxiliary equipment, such as oil pumps.
gearset: Apinionandgearthatareintendedtorun profile shift: A modification of a gear where the
together. tooth profile is radially shifted.
protuberance cutter: A tool for cutting gear teeth
grinding notch: A discontinuity produced by a
that cuts a relief in the profile of the gear teeth to
grinding tool between the start of active profile and
tooth root that increases the tooth root stress. avoid grinding notches.
6 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
purchaser:Entitythatissuespurchasecontractsfor
4 Designspecification
wind turbine gearboxes.
4.1 Introduction
rimthickness: Theradialdistancefromtherootsof
Thisclauseprovidestheminimumrequiredinforma-
the teeth to the inner diameter of the rim or to the
tionforthespecificationofwindturbinegearboxes. It
boreonanexternalgear,andtotheoutsidediameter
is important for the purchaser to identify what is
on an internal gear.
expected of the gearbox manufacturer. A thorough
specification is the method by which this is done.
splitpowerpath: Ageararrangementconsistingof
The scope of the specification may range from only
multiple parallel axis gears. The arrangement is
performance and life requirements to detailed de-
analogous to epicyclic gears except there is no
signandmethodofcalculationrequirements. Ifwind
annulus gear.
turbine certification is required, the purchaser shall
spur gear: Gear with teeth that are parallel to the
clearlyspecifyallcertificationdocumentsrelevantto
gear axis.
the gearbox. The specification should contain the
information noted in annex E.
star: An epicyclic gear arrangement where the
annulusrotates,theplanets(stars)rotateabouttheir 4.2 Specificationintroduction
own axes, and the planet carrier is fixed.
An introduction shall be provided that identifies the
intent of the procurement specification. This shall
throughhardening: Heattreatmentprocesswhere
include a description of the type of wind turbine, its
gear blanks are austenitized, rapidly quenched to
basic modes of operation, the application of the
obtain a predominantly martensitic microstructure,
gearboxinthewindturbine,andadescriptionofthe
and tempered. Gear teeth are machined after
interfaces to the gearbox such as generator, rotor,
through hardening to avoid distortion.
bedplate, torque arm, lubricant system and
NOTE: Throughhardeningdoesnotimplythatthepart
accessories.
hasequivalent hardnessthroughouttheentirecross--
4.3 Gearboxconfiguration
section.
4.3.1 Configuration
torquearm: Astructuralcomponentthatattachesto
The general configuration of the gearbox shall be
the housing of a shaft mounted gearbox and
specified. This may include: the type of mounting;
prevents rotation of the gearbox about the rotor
the type of gearing; the gear arrangement; the
shaft.
numberofhighspeedshafts;thelocationandtypeof
wheel: Of two gears in a gearset, the one with the
power take--off gears (PTO); and the method of
larger number of teeth is the wheel. Also known as
lubrication.
the gear.
All requirements for the geometric configuration of
3.4 Filtrationterms thegearboxshallbespecified. Thismayinclude:the
overalllength,width,orheight;thedistancebetween
cleanlinesslevel: Thecleanlinesslevelasdefined
shaft centers; length of shaft extensions; angle of
by ISO 4406 is a code system used to quantify the
shaft tilt or offset; gear housing split plane; the
number of particles of a certain size in a given
maximum weight, or other features.
volume of oil. See annex F.
A detailed description of all components interfaced
filter: A device for removing solid particles from a
to the gearbox shall be provided. Each interface
liquid stream, typically by means of porous media.
shall be detailed for mounting, support and loading.
4.3.2Rotorspeed
inline filter: A filter installed in the main oil
circulation systemthat supplies gears andbearings
Therotorspeed,orspeedrange,shallbespecified.
with oil.
This shall include expected speed during power
productionandidlingmode. Thedirectionofrotation
offline filter: A filtration device independent of the
for each of these situations shall be specified.
main lubrication system, typically with a separate
4.3.3 Gearratio
pump, that operates continuously to improve oil
cleanliness. Also called bypass filter, kidney loop The overall gear ratio and its tolerance shall be
filter, or side stream filter. specified for the drive gears and any PTO gears.
ISO 81400--4:2005(E)
The overall gear ratio of the gearbox is set by the It shall be clearly stated as to which portion of the
requirements for rotor speed and generator speed. turbine lifetime the spectrum refers.
However, if there is more than one stage of gears,
For variable speed wind turbines, it may be neces-
thegearbox manufacturer can selectgear ratios for
sary to separate each torque bin into severalspeed
eachstagetomaximizeloadcapacity andminimize
bins.
weight (see AGMA 901--A92).
Specifiedtorquelevelofeachbinshallrepresentthe
4.4 Loading
highest level of torque represented in that bin. To
avoid excessive conservatism, sufficient quantity of
4.4.1 Descriptionofloads
bins(atleast40)shallbeused. Binwidthneednotbe
Itistheresponsibilityofthewindturbinemanufactur-
uniform, and, in fact, finer resolution at the highest
ertoprovideallloadsappliedtothegearboxtoallow
torque bins is preferred. The load spectrum shall
adequate evaluation of the design life requirements
also contain one bin that accounts for idling and
for all gears, bearings, shafts and the housing (see
stoppedtime. Theloadspectrumtotaltimewillthen
annex B). The details of this load description are
match the design life of the turbine.
presented in the following sections.
The torque spectrum shall include all fatigue loads,
including all external transient loads such as brake
The loads should be thoroughly detailed in a load
loads,ifapplicable. Ifmorethanasingledrivenload,
description document. This document should
such as multiple generators, pump drives, or other
include:
PTO’s exist, the torque spectrum for each driven
-- torque--frequency histogram including all
load shall be defined.
operating loads;
4.4.2.2Extremetorqueloads
-- transient loads described as annotated time
Extremetorqueshallbespecifiedbythewindturbine
series. RefertosectionB.5.2.2andfigureB.2 for
a sample of an annotated brake event; manufacturer:
-- torque level;
-- torque--speed relationships; and
-- number of occurrences;
-- other structural loads described in fatigue--
basedcyclecountsatpertinentinterfaces. These
-- source, such as rotor, generator or brake.
loads can be presented as a representative time
Extreme loads shall not be included in the load
series of the loads or the results of a Rainflow
spectrum.
Count [1] with mean value, amplitude (peak--to--
peak), and frequency of occurrence.
4.4.3Structuralloads
The purchaser shall indicate in the loads document
4.4.3.1Non--torqueloadsources
thepartialsafetyfactorsandloaduncertaintyfactors
In the case that the wind turbine rotor operation
usedinderivingtheloads. Anyadditionalmultipliers
imparts non--torqueloads tothegearbox low speed
to be applied to the loads shall be explicitly stated.
shaft, these loads shall be sufficiently described in
The source and rationale for the use of the safety
the specification. Such loads may occur in any
factors or multipliers or both shall be described or
operating mode of the wind turbine including idling
sufficiently referenced.
mode or when the turbine is parked. In modular
4.4.2Torqueloads arrangementstheshaftsare subjectedto loadsthat
need to be tolerated and transferred to the base
4.4.2.1Fatigue
mount (see A.5). Also, the generator, brake and
other interfaced components can affect reaction
The low speed shaft torque spectrum shall be
loads on the gearbox and shafts. Such loads may
specified in bins with:
occur in any operating mode of the wind turbine
-- torque level;
includingidlingmodeor whentheturbineis parked.
These loads shall be sufficiently described in the
-- cycles or revolutions per torque level;
specification. Stiffness in all loading directions of
-- nominal speed for design;
compliant supports, such as elastomeric bushings,
-- idling speed. shall be specified by the purchaser.
8 © ISO 2005 ---- All rights reserved

ISO 81400--4:2005(E)
4.4.3.2Structuralfatigueloads 4.4.5 Dynamicloading
The loads specified by the purchaser shall include
For each type of external load applied to the
effects from the system’s dynamics. Depending on
gearbox, fatigue loads shall be defined at the
the layout of the drive train and nacelle, the
interface in a prescribed coordinate system as
purchaser should quantify static and dynamic rela-
moments and forces in three directions.
tivedisplacementsofthedifferentsubsystems. The
Loads for each axis shall be defined in a spectrum,
purchaser shouldalsospecify absolutemovements
specified by bins, with:
andaccelerationsofthegearbox. Implementationof
this dynamic analysis is a joint effort between
-- moment level;
purchaserandgearboxmanufacturer. Toenablethe
-- force level; purchaser to perform the dynamic analysis during
the development process, the gearbox manufactur-
-- cyclesperrevolutionpermoment/forcelevel.
er should supply general gearbox data, such as
Multi--axisloadsshallbeprovidedinsuchawaythat center of gravity, stiffness, inertia, damping, and
thephaserelationshipispreserved. Theinterpreta- clearances.
tionanduseofdatashallbeajointeffortbetweenthe
4.5Certification
wind turbine manufacturer and the gearbox
Wind turbines are usually certified to facilitate due
manufacturer.
diligence efforts and insurance requirements. All
4.4.3.3Structuralextremeloads
requirements for certification shall be described in
the specification, including:
For each type of external loading to the gearbox,
– name of classification society;
extreme loads shall be defined at the interface, in a
prescribed coordinate system, with moments and – standard or certification document name,
number, and revision level;
forces in three directions.
– applicable section or paragraphs;
4.4.4 Idling,parkingandtransientoperation
– any exceptions to the above documents.
Featuressuchasdurationandfrequencyofspeeds
Safety factors in excess of certification standard
and loads, method of lubrication, and temperature
requirementsshallbespecified. Itistheresponsibil-
rangesduringidling,parkingandtransientoperation
ityofthepurchaserthatthepurchasespecificationis
shall be specified.
consistent with the relevant certification standards.
4.4.4.1 Idling
4.6 Operatingenvironment
Theexpectedoperatingenvironmentofthegearbox
Rotors shouldbeallowed toidle whenever possible
shall be specified. As a minimum this shallinclude:
to avoid false brinelling, fretting corrosion, and
theambienttemperaturerange,airtemperatureand
corrosionongearteeth, splines,bearingrollersand
air velocity across the gearbox, maximum relative
bearing raceways.
humidity, extent of exposure to direct sunlight,
4.4.4.2 Parking
precipitationandairborneparticulates.SeeannexE
for additional information on this subject.
Parking should be minimized to avoid false brinel-
4.7 Controlandmonitoring
ling, fretting corrosion, and corrosion on gear teeth,
splines, bearing rollers, and bearing raceways.
Requirements for monitoring and control sensors
Dynamic loads on a parked wind turbine shall be
associatedwiththegearboxshallbespecified. This
specifiedindetail,forexample,byanannotatedtime
may include: lubricant level, temperature, pressure
series.
sensors, vibration sensors, filter bypass sensors,
particulate accumulation sensors, or others.
4.4.4.3 Transientoperations
4.8 Qualificationtesting
Transient load events such as braking, cut--in,
4.8.1 Prototypetests
cut--out,generatorshift, andbladepitchoperations,
shall be specified in detail, for example, by an Typeandconditionsofanyqualificationtestingshall
annotated time series. be specified. These tests shall be performed on a
ISO 81400--4:2005(E)
prototype unit of the gearbox with gears and tion. Atthispoint,theroughnessprofileofgearsand
housings previously measured and recorded. Test bearings is still dominated by the texture generated
duration shall be agreed to between the purchaser inthefinishingprocess. Highlocalcontactstressat
and gearbox manufacturer. The test shall observe roughness peaks may cause micropitting, surface
the development of contact pattern with rising load distress, scuffing or other irreversible wear pro-
(documented at defined steps). The test shall be cesses. The surface finish achieved during the
performed up to the design load for the helix and manufacturing process significantly influences
profile modifications. The test results shall be well these risks. Methods like super--finishing, surface
documentedbyphotosandshallbecomparedtothe plating or run--in at controlled power levels may be
design calculations in order to verify the calculation required to reduce these risks.
model. In addition, bearing and oil temperatures
The wind turbine manufacturer and the gearbox
should be reported. Typical test length should be a
manufacturershallmutuallyagreeamongtheabove
function of the time required for system tempera-
methods with consideration of the actual geometry,
tures to stabilize.
manufacturing processes, stress level, slide ratio,
λ--ratio, and operating modes of the wind turbine.
In addition to the contact pattern development and
The suitability of the selected means shall be
thermal capacity test, an instrumented overload,
documented, for example, by prototype testing.
long duration prototype qualification test may be
When possible, the wind turbine operator should
required. Test conditions for such a test are to be
also agree on the above methods.
agreed to between the purchaser and the gearbox
manufacturer at the time of purchase.
Uncertainties of the wind make it difficult to achieve
properrun--inconditionsduringfieldcommissioning,
4.8.2 Soundemissiontesting
therefore a run--in will typically be performed at the
Acceptance tests for verification of the sound
factory. Operating and load conditions of a run--in
emissions from the gearbox shall be specified.
shallbeselectedwithcaretoavoidinitialdamageto
Testing conditions for the acceptance measure-
gears and bearings. Refer to table 17 for oil
ments shall also be specified. ANSI/AGMA
cleanliness at the run--in test.
6025--D98(soundpressuremeasurement)andISO
The wind turbine manufacturer and the gearbox
8579--1 (sound power measurement) are two pos-
manufacturershallmutuallydetermineandagreeto
sible methods for measurement. The specification
startup,commissioning,operatingandmaintenance
of test conditio
...

NORME ISO
INTERNATIONALE 81400-4
Première édition
2005-10-01
Aérogénérateurs —
Partie 4:
Conception et spécifications relatives
aux boîtes de vitesses
Wind turbines —
Part 4: Design and specification of gearboxes

Numéro de référence
©
ISO 2005
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ii © ISO 2005 – Tous droits réservés

Sommaire Page
Avant-propos .vi
Introduction.vii
1 Domaine d'application .1
2 Références normatives.1
3 Définitions et symboles .3
4 Spécifications de conception.15
5 Exigences relatives à la conception et à la fabrication des boîtes de vitesses.20
6 Lubrification.47
7 Autres éléments importants.54
Bibliographie.135

Annexes
Annexe A (informative) Architecture des aérogénérateurs .57
Annexe B (informative) Description de la charge des aérogénérateurs .64
Annexe C (informative) Assurance qualité.74
Annexe D (informative) Fonctionnement et maintenance .82
Annexe E (informative) Données de commande minimales de l'acheteur et du fabricant de la boîte
de vitesses .86
Annexe F (informative) Surveillance du choix et de l'état de la lubrification .94
Annexe G (informative) Informations générales relatives aux engrenages.116
Annexe H (informative) Détermination du facteur d'application, K , à partir d'un spectre de charge
A
donné en utilisant le couple équivalent, T .118
eq
Annexe I (informative) Calcul des contraintes des roulements .123

Figures
Figure 1 — Boîte de vitesses à axes parallèles à 3 étages .35
Figure 2 — Boîte hybride planétaire/hélicoïdale à 3 étages.36
Figure 3 — Assemblage des roulements .38
Figure A.1 — Éolienne à axe horizontal (EAH).58
Figure A.2 — Schéma de la disposition d'une nacelle pour une EAH .59
Figure B.1 — Variation périodique caractéristique du couple d'arbre .70
Figure B.2 — Couple sur l'arbre du rotor pendant le freinage.71
Figure F.1 — Exemple pour la conception de circuit, système de combinaison de la filtration et
du refroidissement .99
Figure G.1 — Nomenclature des engrenages.116
Figure H.1 — Intervalles de charge présentant un comportement équivalent en termes de
détérioration suivant l'Équation H.3 .119
Figure H.2 — Intervalles (T , n ) et (T , n ) remplacés par l'intervalle (T , n ) .121
1 1 2 2 2 2e
Figure H.3 — Spectre de charge avec le couple équivalent correspondant, T .121
eq
Figure I.1 — Effets du jeu et de la précharge sur la distribution de la pression dans les
roulements radiaux à rouleaux.126
Figure I.2 — Nomenclature de la courbure des roulements .126
Figure I.3 — Distribution de la pression sur la surface de contact elliptique .128

Tableaux
Tableau 1 — Symboles.4
Tableau 2 — Durée de vie nominale de base minimale, L .23
h10
Tableau 3 — Valeurs indicatives pour la pression maximale de contact dans le cas des
roulements à éléments roulants soumis à une charge équivalente dynamique au niveau
du roulement suivant la somme de Miner.24
Tableau 4 — Température de fonctionnement du lubrifiant de roulement pour le calcul du rapport
de viscosité, k.26
Tableau 5 — Gradients de température pour le calcul du jeu en fonctionnement .27
Tableau 6 — Exactitude requise pour les engrenages .30
Tableau 7 — Rugosités de surface recommandées pour les dents de roues.31
Tableau 8 — Roulements pour des charges combinées.32
Tableau 9 — Roulements pour une charge radiale pure .34
Tableau 10 — Roulements pour des charges axiales pures.34
Tableau 11 — Matrice de sélection des paliers - Légendes des symboles .38
Tableau 12 — Matrice de sélection des roulements pour l'arbre à petite vitesse/le porte-satellites.39
Tableau 13 — Matrice de sélection des roulements pour l'arbre intermédiaire à petite vitesse.40
Tableau 14 — Matrice de sélection des roulements pour l'arbre intermédiaire rapide.41
Tableau 15 — Matrice de sélection des roulements pour l'arbre rapide.42
Tableau 16 — Matrice de sélection des roulements pour la roue planétaire .43
Tableau 17 — Propreté des lubrifiants .49
Tableau B.1 — Cas des charges de calcul des aérogénérateurs .67
Tableau C.1 — Echantillon de plan AQ.78
Tableau F.1 — Sources d'éléments métalliques.105
Tableau F.2 — Signification des codes ISO.108
Tableau F.3 — Caractéristiques des particules.110
Tableau F.4 — Limites analytiques pour les lubrifiants utilisés dans les boîtes de vitesses pour
aérogénérateur.111

Tableau F.5 — Indice de viscosité à la température de fonctionnement de la masse d’huile pour
les huiles ayant un indice de viscosité de 90 .112
iv © ISO 2005 – Tous droits réservés

Tableau F.6 — Indice de viscosité à la température de fonctionnement de la masse d'huile pour
les huiles ayant un indice de viscosité de 120.113
Table F.7 — Indice de viscosité à la température de fonctionnement de la masse d'huile pour les
huiles ayant un indice de viscosité de 160.114
Tableau F.8 — Indice de viscosité à la température de fonctionnement de la masse d'huile pour
les huiles ayant un indice de viscosité de 240.115
Tableau H.1 — Exposant p et nombre de cycles de charges N .120
L ref
Tableau H.2 — Exemple de calcul de K à partir d'un spectre de charge .122
A
Tableau I.1 — Facteurs pour les roulements radiaux sous contrainte statique.124

Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 81400-4:2005 a été élaborée par l'AWEA et l'AGMA (sous la référence ANSI/AGMA/AWEA 6006-A03)
et a été adoptée par procédure spécifique «voie express» par l'ISO/TC 60, Engrenages, en coopération avec
le comité technique CEI/TC 88, Éoliennes, en parallèle de son approbation par les comités membres de l'ISO
et de la CEI.
L'ISO 81400-4 est une partie de la série CEI 61400. Elle est destinée à être publiée et remplacée par la
CEI 61400-4 à la prochaine révision.
vi © ISO 2005 – Tous droits réservés

Introduction
La vitesse d'un aérogénérateur augmentant, le fonctionnement et le chargement de la boîte de vitesses sont
différents de la majorité des applications d'engrenages. L'intention de la présente norme est de décrire ces
différences. La plupart des informations sont basées sur l'expérience acquise sur le terrain. La présente
norme est un outil qui permet aux fabricants d'aérogénérateurs et d'engrenages de communiquer et
comprendre les besoins de chacun en développant les spécifications de boîtes de vitesses pour des
applications d'aérogénérateur. Les annexes présentent des discussions informatives de questions diverses
spécifiques aux applications d'aérogénérateurs et à la conception de la boîte de vitesses.
Un comité joint de membres de l'American Wind Energy Association (AWEA) et de l'American Gear
Manufacturers Association (AGMA), représentant des fabricants d'aérogénérateurs, des opérateurs, des
chercheurs, des consultants, ainsi que des fabricants d'engrenages, de roulements et de lubrifiant
internationaux sont responsables de l'élaboration de la présente norme.
La première réunion du comité a eu lieu en 1993 pour développer l'AGMA/AWEA 921-A97, Pratiques
recommandées pour la conception et la spécification des boîtes de vitesses pour les systèmes
d'aérogénérateur. Le document d'information de l'AGMA a été approuvé par le comité AGMA/AWEA sur les
engrenages pour aérogénérateurs le 25 octobre 1996 et par le comité d'exécution de la division technique de
l'AGMA le 28 octobre 1996. La présente norme remplace l'AGMA/AWEA 921-A97.
Le premier projet ANSI/AGMA/AWEA 6006-A03 a été élaboré en mars 2000. Il a été approuvé par les
membres de l'AGMA en 2003. Il a été approuvé par l'«American National Standards Institute» (ANSI) le
9 janvier 2004.
NORME INTERNATIONALE ISO 81400-4:2005(F)

Aérogénérateurs —
Partie 4:
Conception et spécifications relatives aux boîtes de vitesses
1 Domaine d'application
La présente norme s'applique aux boîtes de vitesses pour aérogénérateurs, dont la puissance est comprise entre
40 kW et 2 MW. Elle s'applique à toutes les boîtes de vitesses sous carter, qu’elles soient à axes parallèles,
épicycloïdales à une seule phase, ou bien qu’elles comprennent des combinaisons d'engrenages épicycloïdaux à
une phase et à axes parallèles. Les dispositions de la présente norme sont fondées sur l'expérience acquise sur le
terrain avec des aérogénérateurs du type de ceux cités plus haut en termes de puissance et de configuration.
Les lignes directrices présentées dans la présente norme peuvent être appliquées à des aérogénérateurs de plus
grande capacité, à condition que les spécifications soient modifiées en conséquence.
Les exigences relatives à la durée de vie s'appliquent aux aérogénérateurs ayant une durée de vie théorique d'au
moins 20 ans.
2 Références normatives
Les normes suivantes contiennent des dispositions qui, par suite de la référence qui y est faite, constituent des
dispositions valables pour la présente norme. Au moment de la publication, les éditions indiquées étaient en
vigueur. Toute norme est sujette à révision et les parties prenantes des accords fondés sur la présente norme sont
invitées à rechercher la possibilité d'appliquer les éditions les plus récentes des documents indiquées ci-après.
AGMA 901-A92, A Rational Procedure for Preliminary Design of Minimum Volume Gears
AGMA 913-A98, Method for specifying the Geometry of Spur and Helical Gears
AGMA 925-A03, Effect of Lubrication on Gear Surface Distress
AMS 2301, Aircraft quality steel cleanliness, magnetic particle inspection procedure
ANSI Y12.3-1968, Letter symbols for quantities used in mechanics of solids
ANSI/AGMA 1012-F90, Gear Nomenclature, Definitions of terms with symbols
ANSI/AGMA 2101-D04, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear
Teeth
ANSI/AGMA 6000-B96, Specification for Measurement of Linear Vibration on Gear Units
ANSI/AGMA 6001-D97, Design and Selection of Components for Enclosed Gear Drives
ANSI/AGMA 6025-D98, Sound for Enclosed Helical, Herringbone, and Spiral Bevel Gear Drives
ANSI/AGMA 6110-F97, Standard for Spur, Helical, Herringbone and Bevel Enclosed Drives
ANSI/AGMA 6123-A88, Design Manual for Enclosed Epicyclic Metric Module Gear Drives
ANSI/AGMA 9005-E02, Industrial Gear Lubrification
ASTM A534, Standard specification for carburizing steels for anti-friction bearings
o
Det Norske Veritas Classification AS, Classification Notes N 41.2, Calculation of Gear Rating for Marine
Transmissions, July 1993
DIN ISO 281 Bbl. 4:2003, Dynamische Tragzahl und nominelle Lebensdauer — Verfahren zur Berechnung der
modifizierten Referenzlebensdauer für allgemein belastete Wälzlager (Dynamic load ratings and life — Method for
1)
calculation of the modified reference rating life for generally loaded rolling bearings)
DIN 743:2000, Tragfähigkeitsberechnung von Wellen und Achsen (Calculation of load capacity shafts and axles)
DIN 6885-2:1967, Drive type fastenings without taper action, parallel keys, keyways
DIN 7190:2001, Interference fits ― Calculation and design rules
ISO 76:1987, Roulements ― Charges statiques de base
ISO 281:1990, Roulements ― Charges dynamiques de base et durée nominale
ISO R773:1969, Clavetage par clavettes parallèles carrées ou rectangulaires (Dimensions en millimètres)
ISO 1328-1, Engrenages cylindriques ― Systèmes ISO de précision ― Partie 1: Définitions et valeurs admissibles
des écarts pour les flancs homologues de la denture
ISO 4406:1999 (SAE J1165), Transmissions hydrauliques ― Fluides ― Méthode de codification du niveau de
pollution particulaire solide
ISO 6336-1:1996, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale ―
Partie 1: Principes de base, introduction et facteurs généraux d'influence
ISO 6336-2:1996, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale ―
Partie 2: Calcul de la résistance à la pression de contact (piqûres)
ISO 6336-3:1996, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale ―
Partie 3: Calcul de la résistance à la flexion en pied de dent
ISO 6336-5:1996, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale ―
Partie 5: Résistance et qualité des matériaux
2)
ISO/DIS 6336-6 , Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale ―
Partie 6: Calcul de la durée de vie en service sous charge variable
ISO 8579-1:2002, Code de réception des engrenages sous carter ― Partie 1: Code d'essai pour la détermination
du bruit aérien
ISO 8579-2:1993, Code de réception des engrenages ― Partie 2: Détermination des vibrations mécaniques d'une
transmission par engrenages au cours des essais de réception
ISO/TR 13593:1999, Transmissions de puissance par engrenages sous carter pour usage industriel

1) Traduction anglaise disponible dans le document ISO/TC 4/SC 8 N 254a
2) Actuellement en phase d'élaboration
2 © ISO 2005 – Tous droits réservés

ISO/TR 13989-1:2000, Calcul de la capacité de charge au grippage des engrenages cylindriques, coniques et
hypoïdes ― Partie:1 Méthode de la température-éclair
ISO 14104:1995, Engrenages ― Contrôle par attaque chimique des zones revenues lors de la rectification
ISO/TR 14179-1:2001, Engrenages ― Capacité thermique ― Partie 1: Capacité des transmissions par engrenages
pour une température de bain d'huile de 95°C
3 Définitions et symboles
3.0 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés de 3.2 à 3.4 et les suivants s’appliquent,
ainsi que, si applicables, ceux conformes à l'ANSI/AGMA 1012-F90 et à l'ANSI Y12.3-1968.
3.1 Symboles
Les symboles, termes et unités utilisés dans la présente norme sont indiqués dans le Tableau 1.
NOTE Les symboles et termes contenus dans le présent document peuvent varier par rapport à ceux utilisés dans d'autres
normes AGMA. Il convient que les utilisateurs de la présente norme s'assurent d'utiliser ces symboles et termes de la manière
indiquée dans le présent document.
3.2 Termes relatifs aux aérogénérateurs
3.2.1
orientation active
système conçu pour faire tourner la nacelle en fonction de la direction changeante du vent
NOTE Voir orientation passive.
3.2.2
profil aérodynamique
section transversale bidimensionnelle d'une pale
3.2.3
vitesse moyenne annuelle du vent
moyenne temporelle de la vitesse horizontale du vent pendant une année calendaire en un site particulier et à une
hauteur spécifiée
3.2.4
intensité moyenne annuelle de turbulence
mesure de la variation spatiale à court terme de la vitesse du vent d'afflux autour de sa moyenne à long terme
3.2.5
disponibilité
rapport du nombre d'heures durant lesquelles un aérogénérateur peut fonctionner sur le nombre total d'heures au
cours de cette période, habituellement exprimé en pourcentage
NOTE Le temps d'indisponibilité correspond en général au temps d'arrêt dû à des défaillances ou à des interventions de
maintenance (programmées ou non).
3.2.6
socle
châssis
structure qui soutient, dans un système modulaire, les composants du train d'entraînement et le capot de la nacelle
3.2.7
pale
composant du rotor qui convertit l'énergie éolienne en rotation de l'arbre du rotor
3.2.8
frein
dispositif capable d'arrêter la rotation du rotor ou d’en réduire la vitesse
3.2.9
certification
évaluation de la conformité
procédure par laquelle un tiers assure par écrit qu'un produit, un procédé ou un service est conforme aux
exigences spécifiées
3.2.10
norme de certification
norme décrivant les règles spécifiques des procédures à suivre pour établir une certification de conformité
3.2.11
système de contrôle
système qui contrôle l’aérogénérateur et son environnement et règle l’aérogénérateur de manière à le maintenir
dans les limites de fonctionnement
Tableau 1 — Symboles
Symbole Terme Unités Endroit où
il est utilisé pour
la première fois
C
Charge nominale dynamique de base N Eq 1
C Charge nominale statique de base N 5.1.3.1
f Défaut d’alignement d'engrènement — 5.1.1.3
ma
K Rapport du couple équivalent sur le couple nominal — 5.1.1.5
A
K Facteur de distribution longitudinale de charge — 5.1.1.2
Hβ
K
Rapport de la pression de contact maximale sur la pression de — Eq 4
lc
contact dans le cas d'un contact linéaire sans défaut d’alignement
K
Rapport de la pression maximale de contact avec défaut — Eq 4
m
d’alignement sur la pression maximale de contact sans défaut
d’alignement
K Facteur dynamique — 5.1.1.1
v
k Facteur de répartition des charges pour le rouleau supportant la — Eq 2
charge maximale
L Durée nominale avancée combinée heures 5.1.3.2.3
adv
ème
L Durée nominale avancée sur le i niveau de charge heures Eq 5
adv, i
L Durée (de vie) nominale de base heures Eq 1
h10
L
Longueur effective d'un rouleau mm Eq 3
we
L Durée (de vie) de référence nominale combinée heures 5.1.3.2.3
10r
n
Vitesse de rotation tr/min Eq 1
P Charge dynamique équivalente appliquée aux roulements N Eq 1
P Charge statique équivalente appliquée aux roulements N 5.1.3.1
o
P
Puissance assignée de l’aérogénérateur kW Eq 6
t
p Exposant dans l'équation de durée de vie des roulements — Eq 1
p
Pression de contact dans le cas d'un contact linéaire MPa Eq 3
line
p Pression maximale de contact MPa Tableau 3
max
Q Charge maximale appliquée à un seul rouleau pour un roulement N Eq 2
sans jeu
Q Quantité d'huile recommandée litres Eq 6
ty
4 © ISO 2005 – Tous droits réservés

Symbole Terme Unités Endroit où
il est utilisé pour
la première fois
ème
q Partage de temps sur le i niveau de charge — Eq 5
i
Ra Rugosité moyenne 5.2.8.2
µm
Rz
Hauteur moyenne de crête à creux µm 5.2.8.2
S Facteur de sécurité pour la résistance à la flexion — 5.1.1.4
F
S Facteur de sécurité pour la résistance à la formation de piqûres — 5.1.1.4
H
Y
Facteur de cycle de contrainte pour la résistance à la flexion — 5.1.1.4
N
Y Facteur de durée pour la flexion — 5.1.1.5
NT
Z
Nombre total d'éléments roulants — Eq 2
Z Facteur de cycle de contrainte pour la résistance à la formation de — 5.1.1.4
N
piqûres
Z Facteur de durée pour la résistance à la formation de piqûres — 5.1.1.5
NT
Angle de contact nominal du palier degrés Eq 2
α
Somme des courbures pour le contact linéaire — Eq 3
Σ
ρline
κ Rapport de viscosité — 5.1.3.3

3.2.12
vitesse de démarrage
vitesse du vent la plus basse, située à la hauteur du moyeu, à laquelle le système de contrôle commande à
l’aérogénérateur de produire de la puissance
3.2.13
vitesse de coupure
vitesse maximale du vent à la hauteur du moyeu, à laquelle le système de contrôle commande à l’aérogénérateur
de produire de la puissance
3.2.14
amortisseur d'orientation
dispositif utilisé pour ralentir les mouvements d'orientation
3.2.15
durée de vie calculée
intervalle de temps effectif durant lequel il est prévu que le système continue de fonctionner
NOTE Il comprend les temps de fonctionnement, de marche au ralenti et d'arrêt.
3.2.16
aérogénérateur sous le vent
éolienne à axe horizontal (EAH) dans laquelle le vent atteint le mât avant le rotor
3.2.17
charge équivalente dynamique appliquée aux roulements
charge hypothétique, constante en grandeur et en direction, agissant radialement sur des roulements radiaux ou
axialement sur des butées, qui, si elle est appliquée, a le même effet sur la durée de vie des roulements que les
charges réelles auxquelles le roulement est soumis
3.2.18
coupure d'urgence
arrêt rapide de l'aérogénérateur déclenché par le système de contrôle, par un système de protection ou par une
intervention manuelle
3.2.19
charge extrême
charge simple la plus élevée, de fonctionnement ou non, d’origine quelconque, agissant sur la boîte de vitesses au
cours de sa durée de vie calculée, au-delà de laquelle elle ne satisfait plus aux exigences pour lesquelles elle a été
conçue
NOTE Cette charge peut être une force, un moment, un couple ou une combinaison de ceux-ci. Elle est indiquée par le
fabricant d'aérogénérateurs et comprend tous les facteurs partiels de sécurité des charges.
3.2.20
couple extrême
couple le plus élevé, d’origine quelconque, agissant sur la boîte de vitesses au cours de sa durée de vie calculée,
au-delà duquel elle ne satisfait plus aux exigences pour lesquelles elle a été conçue
3.2.21
vitesse extrême du vent
vitesse moyenne la plus élevée à court terme du vent auquel est susceptible d'être soumis l'aérogénérateur
pendant sa durée de vie utile
NOTE Elle est généralement fondée sur des estimations statistiques du comportement à long terme de la vitesse du vent.
3.2.22
mise en drapeau
action qui consiste, dans une EAH à pas variable, à faire pivoter les pales de manière à ce que l’énergie produite
soit minimale
3.2.23
rotor à pas fixe
rotor muni de pales dont le pas ne varie pas pendant le fonctionnement
NOTE L'angle de pas des pales du rotor peut être modifié manuellement en fonction des variations du spectre du vent qui
peuvent être saisonnières ou spécifiques à un site.
3.2.24
orientation libre
voir orientation passive
3.2.25
EAH
éolienne à axe horizontal
NOTE L'axe de rotation du rotor est approximativement parallèle à l'horizon.
3.2.26
axe horizontal
axe de rotation du rotor approximativement parallèle à l'horizon
3.2.27
hauteur du moyeu
pour une EAH, la hauteur par rapport au centre du rotor
3.2.28
moyeu
structure qui fixe les pales à l'arbre du rotor
3.2.29
ralenti
condition de fonctionnement dans laquelle le rotor tourne sans que la génératrice produise de l’énergie
6 © ISO 2005 – Tous droits réservés

3.2.30
puissance d'entrée ou énergie mécanique
énergie mécanique mesurée au niveau de l'arbre lent de la boîte de vitesses ou bien au niveau de l'arbre du rotor
de l'aérogénérateur
3.2.31
arbre d'entrée
voir arbre de rotor
3.2.32
système intégré
architecture d'un système dans laquelle le carter de la boîte de vitesses supporte directement le rotor et, dans
certains cas, la ou les génératrices et d'autres composants
NOTE Voir système modulaire.
3.2.33
verrouillage
utilisation d'un dispositif mécanique pour empêcher le mouvement du rotor ou du mécanisme d'orientation
3.2.34
châssis principal
voir socle
3.2.35
arbre principal
voir arbre de rotor
3.2.36
charge maximale de fonctionnement
charge la plus élevée dans le spectre de charge
3.2.37
puissance maximale
niveau le plus élevé d’énergie électrique nette délivrée par un aérogénérateur dans les conditions normales de
fonctionnement
3.2.38
charge dynamique équivalente des roulements suivant la somme de Miner
charge dynamique équivalente des roulements obtenue par combinaison de charges et de vitesses dans un
spectre de vent en utilisant la règle de Miner
3.2.39
système modulaire
architecture d'un système dans laquelle l’assemblage arbre-rotor, la boîte de vitesses, la ou les génératrices et,
éventuellement, un mécanisme d'orientation sont des composants distincts montés dans un châssis commun
NOTE Voir système intégré.
3.2.40
ventilation
condition de fonctionnement dans laquelle la génératrice consomme de la puissance
3.2.41
nacelle
structure, qui contient le train d’entraînement et d'autres composants, placée au sommet d'une EAH
3.2.42
capot de nacelle
carter qui couvre la nacelle
3.2.43
vitesse nominale
vitesse de l'arbre à faible vitesse de la boîte de vitesses à laquelle l’énergie mécanique est définie
3.2.44
fixe
condition de fonctionnement dans laquelle le rotor ne tourne pas
3.2.45
coupure normale
condition de fonctionnement temporaire dans laquelle le rotor décélère depuis la vitesse de fonctionnement jusqu'à
l'arrêt ou la marche au ralenti et la génératrice cesse de produire de la puissance
3.2.46
plage opérationnelle de vitesses du vent
plage des vitesses du vent situées entre la vitesse de démarrage et la vitesse de coupure
3.2.47
arbre de sortie
voir arbre à grande vitesse
3.2.48
immobilisé
condition de fonctionnement dans laquelle le rotor ne tourne pas parce que le frein d'immobilisation est actionné
3.2.49
frein d'immobilisation
dispositif capable d'empêcher le rotor de tourner
3.2.50
orientation passive
les forces du vent sont utilisées pour aligner la nacelle (cercle balayé) par rapport à la direction changeante du vent
NOTE Voir orientation active.
3.2.51
pas
position angulaire des pales du rotor autour de leur axe longitudinal
3.2.52
commande de pas
limitation du couple de l'arbre du rotor obtenue en ajustant activement le pas
3.2.53
maintenance préventive
intervention programmée destinée à empêcher les défaillances ou à éviter les réparations imprévues
3.2.54
puissance nominale
énergie électrique restituée permanente, déclarée par le fabricant d'aérogénérateurs, que l'aérogénérateur est
censé, par conception, délivrer dans les conditions normales de fonctionnement à la vitesse nominale du vent
3.2.55
vitesse nominale du vent
vitesse du vent spécifiée, déclarée par le fabricant du système aérogénérateur, à laquelle la puissance nominale
est générée
8 © ISO 2005 – Tous droits réservés

3.2.56
rotor
ensemble constitué par le moyeu et les pales
3.2.57
roulement(s) de rotor
roulement(s) soutenant l'arbre du rotor
3.2.58
diamètre du rotor (axe horizontal)
diamètre du cercle balayé par la rotation des pales
3.2.59
arbre du rotor
arbre principal
arbre qui supporte le rotor et transmet le couple du rotor à la boîte de vitesses
3.2.60
vitesse du rotor
vitesse de rotation du rotor de l'aérogénérateur autour de son axe, exprimée en nombre de tours par minute
3.2.61
régulation par décrochage aérodynamique
système de régulation où la limitation du couple de l'arbre du rotor est obtenue par conception aérodynamique
(choix du profil aérodynamique, effilement de la pale, vrillage de la pale, pas de la pale, vitesse du rotor)
3.2.62
arrêt
voir anti-giratoire
3.2.63
démarrage
condition temporaire dans laquelle le rotor accélère depuis la position d'arrêt ou la marche au ralenti jusqu'à la
vitesse de fonctionnement et la génératrice commence à produire de la puissance
3.2.64
mât
structure qui supporte la nacelle dans une EAH
3.2.65
intensité de turbulence
mesure statistique de la variation de la vitesse du vent
NOTE Rapport de l'écart-type de la vitesse du vent sur la vitesse moyenne du vent.
3.2.66
aérogénérateur au vent
EAH dans laquelle le vent atteint le rotor avant d'atteindre le mât
3.2.67
rotor à pas variable
rotor dont il est possible de faire varier le pas des pales pendant le fonctionnement
NOTE L'angle de pas peut être commandé afin d'optimiser la puissance ou de limiter les charges en fonction des
conditions.
3.2.68
vitesse variable
système de régulation où la limitation du couple de l'arbre du rotor est réalisée au moyen de composants
électroniques sous haute tension et de modèles spéciaux de génératrices permettant de disposer d'une plage
étendue de vitesses de rotor
NOTE Cette méthode utilise les variations d'énergie inertielle dans le rotor pour absorber l'effet des rafales de vent.
3.2.69
EAV
éolienne à axe vertical
éolienne où l'axe de rotation du rotor est approximativement perpendiculaire à l'horizon
NOTE Ce type d’aérogénérateur ne relève pas du domaine d'application de la présente norme.
3.2.70
aérogénérateur (WTGS)
système qui convertit l'énergie cinétique du vent en énergie électrique
3.2.71
fabricant d'aérogénérateurs
entité qui conçoit, fabrique et garantit des aérogénérateurs
3.2.72
opérateur d'aérogénérateurs
entité qui exploite et entretient des aérogénérateurs
3.2.73
orientation
rotation de la nacelle d'une EAH autour de l'axe longitudinal de son mât
NOTE Elle est utilisée pour orienter la nacelle (cercle balayé) par rapport au vent dominant.
3.2.74
roulement d'orientation
système de roulements qui supporte la nacelle dans une EAH
NOTE Il permet à la nacelle de tourner autour de l'axe du mât.
3.2.75
mécanisme d'orientation
système de composants utilisé pour provoquer un mouvement d'orientation
3.3 Termes relatifs aux boîtes de vitesses
3.3.1
acier allié
acier contenant des quantités significatives d'éléments d'alliage tels que le nickel, le chrome ou le molybdène pour
améliorer ses propriétés telles que la trempabilité ou la résistance
3.3.2
température ambiante
température sèche de l'air prise au voisinage de la boîte de vitesses
3.3.3
couronne de train planétaire
roue à denture intérieure
roue dont la denture se situe sur la surface intérieure d'un cylindre
10 © ISO 2005 – Tous droits réservés

3.3.4
rapport de forme
rapport de la largeur de denture du pignon sur le diamètre primitif de fonctionnement du pignon
3.3.5
durée nominale de base des roulements
durée de vie lorsque les facteurs de réglage relatifs à la fiabilité, au matériau et à l'environnement pris en compte
sont égaux à l’unité (1,0)
3.3.6
fabricant de roulements
entité qui conçoit, fabrique et garantit des roulements destinés à des boîtes de vitesses pour aérogénérateurs
3.3.7
huile en vrac
huile la plus représentative de l'état physique global du lubrifiant au sein du système de lubrification
NOTE Dans le cas des boîtes de vitesses à lubrification par barbotage, le niveau du lubrifiant se trouve à peu près à la
moitié du carter d'huile peu de temps après la coupure du dispositif d'entraînement à la température de fonctionnement. Pour
des systèmes de lubrification sous pression, il s'agit de l'huile contenue dans la canalisation de refoulement entre la pompe à
huile et le filtre pendant le fonctionnement du système.
3.3.8
cémentation
procédé de traitement thermique au cours duquel les engrenages sont chauffés dans une atmosphère riche en
carbone (habituellement, cémentation gazeuse), qui a pour effet de diffuser le carbone dans les couches
superficielles de la denture
NOTE Les engrenages sont durcis par trempe à partir de la température de cémentation ou bien par refroidissement,
réchauffage et trempe. La cémentation et le durcissement sont suivis d'un revenu au cours duquel les engrenages sont
réchauffés à une température relativement basse puis refroidis lentement.
3.3.9
accouplement
dispositif qui relie deux arbres tournants pour transmettre de la puissance, tolérer un défaut d’alignement et
compenser un mouvement axial
3.3.10
engrenage à denture hélicoïdale double
roue d'engrenage comprenant une denture hélicoïdale à droite et une denture hélicoïdale à gauche
NOTE Les dentures hélicoïdales sont séparées par un intervalle.
3.3.11
train épicycloïdal
combinaison d'engrenages composée de multiples engrenages à axes parallèles comprenant un pignon solaire,
plusieurs satellites engrenant avec le pignon solaire, un porte-satellites et une couronne engrenant avec les
satellites
3.3.12
roue d’engrenage
roue
celle des deux roues d'un engrenage qui a le plus grand nombre de dents
NOTE Voir pignon.
3.3.13
boîte de vitesses
ensemble complet de roues, d'arbres, de roulements, d’un carter, de joints, d'un système de lubrification et des
composants associés
3.3.14
fabricant de boîtes de vitesses
entité qui conçoit, fabrique et garantit des boîtes de vitesses pour aérogénérateurs
3.3.15
rapport d'engrenage
rapport du plus grand nombre de dents sur le plus petit nombre de dents dans un engrenage
3.3.16
engrenage
pignon et roue destinés à fonctionner ensemble
3.3.17
entaille de rectification
discontinuité produite par un outil de rectification entre le début d'un profil actif et le pied de la dent, et qui
augmente les contraintes exercées sur le pied de la dent
3.3.18
engrenage à denture hélicoïdale
roue dont les dents sont inclinées par rapport à l'axe de la roue, telle une vis hélicoïdale
3.3.19
correction d’hélice
correction au niveau de la fabrication d'un pignon ou d'une roue, obtenue par modification de la forme du flanc des
dents suivant la largeur de denture
3.3.20
arbre à grande vitesse
arbre ayant la plus grande vitesse dans une boîte de vitesses qui entraîne la génératrice
3.3.21
carter
enveloppe qui contient les composants de la boîte de vitesses tels que les roues, les arbres, les roulements et les
composants associés
3.3.22
bague intérieure
dans un roulement, élément situé entre la dimension intérieure des rouleaux ou des billes et le diamètre extérieur
de la pièce sur laquelle le roulement est monté
3.3.23
correction de profil en développante de cercle
correction au niveau de la fabrication d'un pignon ou d'une roue, au cours de laquelle une petite quantité variable
de matière est enlevée le long du profil des dents dans le sens allant du pied vers la tête
3.3.24
arbre à petite vitesse
arbre ayant la plus petite vitesse dans une boîte de vitesses
NOTE Voir arbre du rotor.
3.3.25
fabricant de lubrifiants
entité qui conçoit, fabrique et garantit des lubrifiants destinés aux boîtes de vitesses pour aérogénérateurs
3.3.26
module
rapport du diamètre primitif en millimètres sur le nombre de dents dans une roue
12 © ISO 2005 – Tous droits réservés

3.3.27
nitruration
procédé de traitement thermique dans lequel les roues sont chauffées dans une atmosphère d'azote pour
permettre la diffusion de l'azote dans les couches superficielles de la denture et la formation de nitrures durs
NOTE La déformation est peu importante parce que la nitruration est effectuée à basse température et qu'il n'y a pas de
trempe.
3.3.28
bague extérieure
dans un roulement, élément situé entre la dimension extérieure des rouleaux ou des billes et l'alésage de la pièce
dans laquelle le roulement est monté
3.3.29
arbres parallèles
combinaison d'engrenages dans laquelle le pignon et la roue s'engrènent sur des axes parallèles
3.3.30
pignon
celle des deux roues dans un engrenage, qui a le plus petit nombre de dents
NOTE Voir roue.
3.3.31
train planétaire
disposition de train épicycloïdal dans laquelle la couronne est fixe, les satellites tournent autour de leur propre axe
et le porte-satellites est mobile
3.3.32
prise de force (PTO)
arbre de sortie supplémentaire destiné à entraîner des équipements auxiliaires, tels que des pompes à huile
3.3.33
déport
modification d'un engrenage dans laquelle le profil est déporté radialement
3.3.34
fraise à protubérance
outil destiné à tailler des dents d'engrenages, capable de découper une dépouille dans le profil de la denture de
l'engrenage, de manière à éviter l'apparition d’entailles de rectification
3.3.35
acheteur
entité qui émet des bordereaux d'achat pour des boîtes de vitesses d'aérogénérateurs
3.3.36
épaisseur de jante
distance radiale allant du pied des dents jusqu'au diamètre intérieur de la jante ou jusqu'à l'alésage sur une roue
externe et jusqu'au diamètre extérieur d'une roue interne
3.3.37
trajet de puissance divisé
combinaison d'engrenages composée de plusieurs roues à axes parallèles
NOTE La disposition est analogue aux trains épicycloïdaux, s
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