Safety of machinery - Two-hand control devices - Functional aspects - Principles for design

This standard specifies the safety requirements of a two-hand control device and its logic unit as defined in
3.1.
This standard describes the main characteristics of two-hand control devices for the achievement of safety
and sets out combinations of functional characteristics for three types. This standard does not apply to
devices intended to be used as enabling devices, hold to run devices and as special control devices.
This standard does not specify with which machines two-hand control devices shall be used. It also does not
specify which types of two-hand-control device shall be used. Moreover it does not specify the distance
between the two-hand control device and the danger zone (see 9.8).
The standard provides requirements and guidance on the design and selection (based on a risk assessment)
of two-hand control devices including their assessment, the prevention of defeat and the avoidance of faults.
The standard also provides requirements and guidance for two-hand control devices containing a
programmable electronic system (see 7).
This standard applies to all two-hand control devices, independent of the energy used, including:
- Two-hand control devices which are or are not integral parts of a machine;
- Two-hand control devices which consist of one or more than one separate elements.

Sicherheit von Maschinen - Zweihandschaltungen - Funktionelle Aspekte - Gestaltungsleitsätze

Diese Norm legt die Sicherheitsanforderungen einer in 3.1 definierten Zweihandschaltung und ihrer Logikeinheit fest.
Diese Norm beschreibt die Haupteigenschaften von Zweihandschaltungen zur Erlangung von Sicherheit und liefert Kombinationen von funktionalen Eigenschaften für 3 Typen. Diese Norm gilt nicht für Einrichtungen, die für die Verwendung als Zustimmungseinrichtung, Befehlseinrichtung mit selbsttätiger Rückstellung (Tippschalter) und als spezielle Steuereinrichtung bestimmt sind.
Diese Norm legt nicht fest, mit welchen Maschinen Zweihandschaltungen angewendet werden sollen. Sie legt ebenfalls nicht fest, welche Typen von Zweihandschaltungen verwendet werden sollen. Darüber hinaus legt sie nicht den Abstand zwischen der Zweihandschaltung und dem Gefahrbereich fest (siehe 9.8).
Die Norm liefert Anforderungen und Anleitungen für die Gestaltung und Auswahl (als Ergebnis der Risikobeurteilung) von Zweihandschaltungen einschließlich ihrer Bewertung, der Verhinderung des Umgehens und des Vermeidens von Ausfällen. Die Norm enthält ebenfalls Anforderungen und Anleitungen für Zweihandschaltungen, die ein programmierbares elektronisches System beinhalten (siehe Abschnitt 7).
Diese Norm gilt für alle Zweihandschaltungen, unabhängig von der Energie, einschließlich:
   Zweihandschaltungen, die integraler Bestandteil einer Maschine sind oder nicht;
Zweihandschaltungen, die aus einer oder mehreren einzelnen Baugruppen bestehen.

Sécurité des machines - Dispositifs de commande bimanuelle - Aspects fonctionnels - Principes de conception

Cette norme spécifie les prescriptions de sécurité d'un dispositif de commande bimanuelle et de son bloc logique
tel que défini en 3.1.
Cette norme décrit les principales caractéristiques des dispositifs de commande bimanuelle permettant d’assurer la
sécurité, et établit des combinaisons de caractéristiques fonctionnelles pour trois types. Cette norme ne s'applique
pas aux dispositifs destinés à être utilisés comme dispositifs de validation, comme dispositifs de commande
nécessitant une action maintenue, ou comme dispositifs de commande spéciaux.
Cette norme ne spécifie pas avec quelles machines les dispositifs de commande bimanuelle doivent être utilisés.
Elle ne spécifie pas non plus quels types de dispositifs de commande bimanuelle doivent être utilisés. Enfin, elle ne
spécifie pas la distance entre le dispositif de commande bimanuelle et la zone dangereuse (voir 9.8).
La norme énonce des prescriptions et des conseils sur la conception et le choix basé sur l’appréciation du risque
de dispositifs de commande bimanuelle y compris leur évaluation, la prévention de la fraude et des défauts. La
norme énonce aussi des prescriptions et des conseils pour les dispositifs de commande bimanuelle comprenant un
système électronique programmable (voir 7).
Cette norme s'applique à tous dispositifs de commande bimanuelle, indépendamment de l'énergie utilisée,
y compris :
- aux dispositifs de commande bimanuelle intégrés ou non à une machine ;
- aux dispositifs de commande bimanuelle en un ou plusieurs éléments séparés.

Varnost strojev - Dvoročne krmilne naprave - Funkcionalni vidiki - Načela načrtovanja

General Information

Status
Withdrawn
Publication Date
21-Aug-2008
Withdrawal Date
06-Aug-2019
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
07-Aug-2019
Due Date
30-Aug-2019
Completion Date
07-Aug-2019

Relations

Buy Standard

Standard
SIST EN 574:1998+A1:2008
English language
31 pages
sale 10% off
Preview
sale 10% off
Preview
e-Library read for
1 day

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 574:1998+A1:2008
01-oktober-2008
9DUQRVWVWURMHY'YRURþQHNUPLOQHQDSUDYH)XQNFLRQDOQLYLGLNL1DþHOD
QDþUWRYDQMD

Safety of machinery - Two-hand control devices - Functional aspects - Principles for

design
Sicherheit von Maschinen - Zweihandschaltungen - Funktionelle Aspekte -
Gestaltungsleitsätze

Sécurité des machines - Dispositifs de commande bimanuelle - Aspects fonctionnels -

Principes de conception
Ta slovenski standard je istoveten z: EN 574:1996+A1:2008
ICS:
13.110 Varnost strojev Safety of machinery
SIST EN 574:1998+A1:2008 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 574:1998+A1:2008
---------------------- Page: 2 ----------------------
SIST EN 574:1998+A1:2008
EUROPEAN STANDARD
EN 574:1996+A1
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2008
ICS 13.110 Supersedes EN 574:1996
English Version
Safety of machinery - Two-hand control devices - Functional
aspects - Principles for design

Sécurité des machines - Dispositifs de commande Sicherheit von Maschinen - Zweihandschaltungen -

bimanuelle - Aspects fonctionnels - Principes de Funktionelle Aspekte - Gestaltungsleitsätze

conception

This European Standard was approved by CEN on 20 November 1996 and includes Amendment 1 approved by CEN on 18 May 2008.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the CEN Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the

official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 574:1996+A1:2008: E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
Contents Page

Foreword..............................................................................................................................................................3

Introduction .........................................................................................................................................................4

1 Scope ......................................................................................................................................................4

2 Normative references ............................................................................................................................5

3 Definitions ..............................................................................................................................................5

4 Types of two-hand control devices and their selection ....................................................................7

5 Characteristics of safety functions......................................................................................................9

6 Requirements related to categories of control.................................................................................10

7 Use of programmable electronic systems ........................................................................................11

8 Prevention of accidental actuation and of defeat.............................................................................12

9 General requirements..........................................................................................................................14

10 Verification ...........................................................................................................................................16

11 Marking .................................................................................................................................................20

12 Information for installation, use and maintenance ..........................................................................21

Annex A (normative) Measurement tests for the prevention of defeat......................................................23

Annex B (informative) Use of categories (according to EN 954-1:1996) in types of two-hand

control devices.....................................................................................................................................28

Annex ZA (informative) !!!!Relationship between this European Standard and the Essential

Requirements of EU Directive 98/37/EC"""".......................................................................................29

Annex ZB (informative) !!Relationship between this European Standard and the Essential

Requirements of EU Directive 2006/42/EC""""...................................................................................30

Bibliography ......................................................................................................................................................31

---------------------- Page: 4 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
Foreword

This document (EN 574:1996+A1:2008) has been prepared by Technical Committee CEN/TC 114 “Safety of

machinery”, the Secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by December 2008, and conflicting national standards shall be withdrawn

at the latest by December 2008.
This document includes Amendment 1, approved by CEN on 2008-05-18.
This document supersedes EN 574:1996.

The start and finish of text introduced or altered by amendment is indicated in the text by tags ! ".

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association, and supports essential requirements of EU Directive(s).

!For relationship with EU Directive(s), see informative Annexes ZA and ZB, which are integral parts of this

document."

This standard is a type B standard in the structure of A-/B-/C-standards as defined in EN 292.

Annex A of this standard is normative, whereas annexes B and C are informative.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and United Kingdom.
---------------------- Page: 5 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
Introduction

This standard has been prepared to be a type B standard in the sense of the Machinery Directive

(89/392/EWG) and associated EFTA regulations.

A two-hand control device is a safety device (safety component). It provides a measure of protection for the

operator against reaching danger zones during hazardous situations by locating the control actuating devices

in a specific position. For hand held machinery it should be taken into consideration that the danger zone is

not stationary.

The selection of a two-hand control device as an appropriate safety device will depend upon the risk

assessment made by designers, standard makers and others in accordance with EN 292-1 and EN 1050.

The definition of a two-hand control device is given in 3.1 and takes precedence over the definition in 3.23.4 of

EN 292-1:1991.

In some arrangements enabling devices (see 3.23.2 of EN 292-1:1991) and/or hold-to-run devices (see 3.23.3

of EN 292-1:1991) may comply with the definition of a two-hand control device in this standard. Additionally,

some special control devices - such as teach pendants for robots and some crane controls – require the use

of two hands and can comply with the definition a two-hand control device in this standard.

1 Scope

This standard specifies the safety requirements of a two-hand control device and its logic unit as defined in

3.1.

This standard describes the main characteristics of two-hand control devices for the achievement of safety

and sets out combinations of functional characteristics for three types. This standard does not apply to

devices intended to be used as enabling devices, hold to run devices and as special control devices.

This standard does not specify with which machines two-hand control devices shall be used. It also does not

specify which types of two-hand-control device shall be used. Moreover it does not specify the distance

between the two-hand control device and the danger zone (see 9.8).

The standard provides requirements and guidance on the design and selection (based on a risk assessment)

of two-hand control devices including their assessment, the prevention of defeat and the avoidance of faults.

The standard also provides requirements and guidance for two-hand control devices containing a

programmable electronic system (see 7).

This standard applies to all two-hand control devices, independent of the energy used, including:

 Two-hand control devices which are or are not integral parts of a machine;

 Two-hand control devices which consist of one or more than one separate elements.

---------------------- Page: 6 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
2 Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications.

These normative references are cited at the appropriate places in the text and the publications are listed in

this clause. For dated references, subsequent amendments to or revisions of any of these publications only

apply to this European Standard when incorporated. For undated references, the latest edition of the

publication applies.

EN 292-1:1991, Safety of machinery, basic concepts, general principles for design — Part 1: Basic

terminology, methodology.

EN 292-2:1991/A1:1995, Safety of machinery, basic concepts, general principles for design — Part 2:

Technical principles and specifications.

prEN 894-1:1992, Safety of machinery, ergonomics requirements for the design of displays and control

actuators – Part 1: Human interactions with displays and control actuators.

prEN 894-2:1992, Safety of machinery, ergonomics requirements for the design of displays and control

actuators – Part 2: Displays.

prEN 894-3:1992, Safety of machinery, ergonomics requirements for the design of displays and control

actuators – Part 3: Control actuators.

EN 954-1:1996, Safety of machinery, safety related parts of control systems — Part 1: General principles for

design.

prEN 999:1995, Safety of machinery, the positioning of protective equipment in respect of approach speeds of

parts of the human body.
EN 1050:1996, Safety of machinery, principles for risk assessment

EN 60204-1:1992, Safety of machinery, electrical equipment of machines – Part 1: General requirements.

3 Definitions
For the purposes of this standard, the following definitions apply:
3.1
two-hand control device

a device which requires at least simultaneous actuation by the use of both hands in order to initiate and to

maintain, whilst a hazardous condition exists, any operation of a machine thus affording a measure of

protection only for the person who actuates it (see figure 1)
---------------------- Page: 7 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
Key
1 input signal
2 two-hand control device
3 control actuating device
4 signal converter(s)
5 signal processor(s)
6 output signal
7 logic unit
Figure 1 — Schematic representation of a two-hand control device
3.2
input signal

the externally actuated signal applied by hand to a control actuating device (see fig. 1)

3.3
control actuating device

a component of the two-hand control device which senses an input signal from one hand and transmits it to a

signal converter (see fig. 1)
3.4
simultaneous actuation

the continuing actuation of both control actuating devices during the same time period, whatever the time lag

is between the start of one input signal and the start of the other (see fig. 2)

NOTE In the English language the word "concurrent" and the word "simultaneous" are often used synonymously (e.g.

see clause 9.2.7 of EN 60204-1:1992).
3.5
synchronous actuation

a particular case of simultaneous actuation where the time lag between the start of one input signal and the

start of the other is less than or equal to 0,5 s (see fig. 3).
---------------------- Page: 8 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
3.6
signal converter

a component of the two-hand control device which receives an input signal from a control actuating device

and which transmits and/or converts this signal into a form acceptable to the signal processor (see fig. 1).

3.7
signal processor

a part of the two-hand control device which generates the output signal as a consequence of the two input

signals (see fig. 1).
3.8
output signal

the signal generated by the two-hand control device to be fed into the machinery to be controlled, and which is

based on one pair of input signals (see fig. 1).
3.9
response time

the time between the release of a control actuating device and the cessation of the output signal (see 9.8)

3.10
mobile two-hand control device

a device which can be moved and used in more than one definable position relative to the danger zone of the

machine which it controls
4 Types of two-hand control devices and their selection

Table 1 defines three types of two-hand control devices. It sets out the functional characteristics and the

minimum measures for the safety of each type of two-hand control device in this standard. All two-hand

control devices shall comply with EN 292 and the relevant parts of EN 60204-1.
---------------------- Page: 9 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)

Table 1 — List of types of two-hand control devices and minimum safety requirements

REQUIREMENTS CLAUSE TYPES
I II III
A B C
Use of both 5.1 X X X X X
hands
(simultaneous
actuation)
Relationship 5.2 X X X X X
between input
signals and
output signal
Cessation of the 5.3 X X X X X
output signal
Prevention of 5.4 X X X X X
accidental
operation
Prevention of 5.5 X X X X X
defeat
Reinitiation of the 5.6 *) X X X X
output signal
Synchronous 5.7 X X X
actuation
Use of category 1 6.2 X X
(EN 954-1:1996)
Use of category 3 6.3 X X
(EN 954-1:1996)
Use of category 4 6.4 X
(EN 954-1:1996)
*) NOTE for the selection of Type I see 8.6.

The selection and the design of the type (see table 1) of two-hand control device will depend on:

 The hazard(s) present;
 The assessment of risk;
 Experience in use of technology;

 Other factors which shall be specified for each application (e.g. the prevention of accidental actuation and

of defeat (see 8), other conditions (see 3 of EN 292-2:1991)).

NOTE Guidance on risk assessment may be found in EN 292-1 and detailed guidance is given in EN 1050

---------------------- Page: 10 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
5 Characteristics of safety functions

The characteristics of safety functions described in 5.1 to 5.7 shall be included in two-hand control devices in

accordance with table 1.
5.1 Use of both hands (simultaneous actuation)

The two-hand control device shall be designed so that the operator shall use both hands during the same time

period, one hand on each control actuating device, to operate the two-hand control device. This is

simultaneous actuation and is independent of any time lag between the initiation of each of the two input

signals (see fig. 2).
Figure 2 — Input signals of simultaneous actuation
5.2 Relationship between input signals and output signal

The input signal applied to each of the two control actuating devices shall together initiate and maintain the

output signal from the two-hand control device only so long as both input signals are applied. The form of the

output signal (e.g. in number of channels, by pulse, shape etc.) may vary according to the design

requirements in each case. It shall always be regarded and shall be identified as a single output signal by the

machine control circuit.
5.3 Cessation of the output signal

The release of either one or both control actuating devices shall initiate the cessation of the output signal.

5.4 Prevention of accidental operation

The probability of operating the control actuating devices accidentally shall be minimised (see 8 and 9).

5.5 Prevention of defeat

The protective effect of the two-hand control device shall not be easily defeated (see 8 and 9).

---------------------- Page: 11 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
5.6 Reinitiation of the output signal

The reinitiation of the output signal shall only be possible after the release of both control actuating devices.

5.7 Synchronous actuation

5.7.1 An output signal shall be generated only when both control actuating devices are actuated in a time

lag which is less or equal to 0,5 s (see figure 3).
Figure 3 — Input signals of synchronous actuation

5.7.2 Mechanical two-hand control devices shall only generate an output signal by satisfying particular

spatial requirements for the travel of both of the control actuating devices.

5.7.3 If the control actuating devices are not actuated synchronously the output signal shall be prevented

and it shall be necessary to release both control actuating devices and to re-apply both input signals.

NOTE Where two or more two-hand control devices are used to operate one machine, synchronous actuation is

required only within each two-hand control device and is not required between devices.

6 Requirements related to categories of control
6.1 Category selection

The behaviour of parts of a two-hand control device in the case of failure shall be in accordance with the

selected category of EN 954-1:1996 (see table 2).

The category of control of two-hand control devices shall not be less than the category of control of the

relevant safety related part of the machine control system (see EN 954-1:1996).

Annex B describes the relationship between the types of two-hand control devices and the categories

according to EN 954-1:1996.
---------------------- Page: 12 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
6.2 Use of category 1

Well-tried safety components and safety principles in accordance with, at least, category 1 of EN 954-1:1996

shall be used in Type I and Type III A two-hand control devices.

NOTE In order to achieve high reliability and high availability it is recommended that well-tried safety components

and safety principles should be used in all types of two-hand control devices
6.3 Use of category 3

When the risk assessment indicates the requirement of single fault safety the two-hand control device of Type

II and Type III B shall comply with category 3 (EN 954-1:1996) and 6.3.1, 6.3.2 and 6.3.3.

6.3.1 The single fault in the two-hand control shall not lead to the loss of the safety function(s).

6.3.2 The two-hand control device shall not be converted into a one-hand control device as a consequence

of the one fault.
6.3.3 An output signal shall not be generated as a consequence of the one fault.

NOTE These requirements do not mean that all faults will be detected. Consequently the accumulation of undetected

faults may lead to the loss of the safety function and to an unintended output of the two-hand control device.

6.4 Use of category 4

When the risk assessment indicates the requirements of automatic-monitoring the two-hand control device of

Type III C shall comply with category 4 (EN 954-1:1996) and 6.3, 6.4.1, 6.4.2, 6.4.3.

6.4.1 The single fault shall be detected at or before the next operation of the safety function(s).

6.4.2 After an occurrence of a fault it shall not be possible to reinitiate an output signal.

6.4.3 An output signal being generated at the time of occurrence of the fault may continue, but shall cease

when either or both input signals are terminated. If a single fault cannot be detected then a combination of

faults shall not lead to a loss of the safety function(s).
7 Use of programmable electronic systems

Where a programmable electronic system (PES) is used to achieve the functional characteristics of a two-

hand control device, the safety requirements of the hardware and in the software of the PES shall be validated

in accordance with the risk assessment.

Secure means shall be provided for the software and the hardware of the PES to ensure that the designed

functional characteristics cannot be tampered with.

The output signal of a two-hand control device Type III B and Type III C shall not be generated and

transferred solely by a single channel PES to the machine control system.

NOTE There is still considerable development in the ways in which programmable electronic systems are being

validated and a list of documents which provide guidance in this subject area is given in Annex C.

---------------------- Page: 13 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
8 Prevention of accidental actuation and of defeat
8.1 Common consideration

The control actuating devices of a two-hand control device shall be designed and arranged in such a way that

the protective effect of the two-hand control device cannot be easily defeated and that the probability of

accidental actuation is minimized, in accordance with the risk assessment for the particular application.

This use of one hand alone, possible combinations of one hand and/or other parts of the body and/or the use

of simple aids which allow defeat shall be considered, so that it shall not be possible to reach into the danger

zone during a hazardous situation. Accidental actuation (e.g. by the clothes of the operator) shall be

considered in the same way.

Simple aids can be e.g. bridges, cords and tapes. The selection of dissimilar actuating directions, covers,

shapes etc. shall minimise the possibilities of defeat. The possibility of a two-hand control device being

operated by two persons thus leaving two hands free, can be overcome by using synchronous actuation.

NOTE Total protection from "defeat" is not possible

The subclauses 8.2 to 8.6 show some separate individual ways in which defeat is possible together with some

precautionary measures for prevention. The methods of defeat that shall be considered will depend on the

design of two-hand control device, the operating conditions, the method of attachment and positioning of the

two-hand control device and the specified safety distance requirements etc.
The subclause 8.7 shows some ways to prevent accidental actuation.

The precautionary measures listed may be required singly or in combination to meet this standard. The test

procedures which shall be applied to the most common types of design are set out in 10.5. For other designs

of two-hand control device these test procedures may or may not be applicable. In these cases a hazard

analysis and an assessment of risk of the possible use and/or misuse of that design of two-hand control

device shall be carried out and appropriate measures shall be taken to comply with this standard.

8.2 Prevention of defeat using one hand

Measures to prevent defeat by using one hand shall be provided. Examples of suitable measures are:

 Separation of the control actuating devices (inside dimension) by at least 260 mm;

 By the provision of one or more shields or an elevated area between the control actuating devices which

is (are) designed in such a way that the control actuating devices are separated by a distance of at least

260 mm around the shields.
8.3 Prevention of defeat using hand and elbow of the same arm

Measures to prevent defeat by using the hand and elbow of the same arm shall be provided. Examples of

suitable measures are:

 Separation of the control actuating devices by at least 550 mm inside dimension. For ergonomic reasons

this distance should not exceed 600 mm;

 By the provision of one or more shields or an elevated area between the control actuating devices which

is (are) designed in such a way that the control actuating devices cannot be touched by the elbow and the

tips of the fingers of the same arm at the same time;

 Covers designed in such a way that the control actuating devices cannot be operated by the elbow;

 Control actuating devices with different types and/or directions of operation.
---------------------- Page: 14 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
8.4 Prevention of defeat using the forearm(s) or elbow(s)

Measures to prevent defeat by using the forearm(s) and/or elbow(s) shall be provided, if the distance of the

hands from the hazard as a result of using forearm(s) and/or elbow(s) is smaller than the required safety

distance.

A suitable measure is using covers and/or collars which are designed so that the control actuating devices

cannot be operated by the forearm(s) and/or the elbow(s).

8.5 Prevention of defeat using one hand and any other part of the body (e.g. knee, hip)

Measures to prevent defeat by using other parts of the body in conjunction with one hand shall be provided.

Examples of suitable measures are:

 Arrangement of the control actuating devices on a horizontal or nearly horizontal surface which is at least

1100 mm above the floor or level of access. This is intended to prevent actuation by the hip;

 In the case of attachment to a vertical or near vertical surface by the provision of a protective collar

around the control actuating devices;

 Covers and/or shields which are designed in such a way that the control actuating devices cannot be

operated by one hand and any other part of the body.
8.6 Prevention of defeat by blocking one control actuating device
Measures to prevent defeat by blocking one actuating device shall be provided.

This method of defeat causes a two-hand control device to become a one-hand control and may cause a

permanent input signal from the blocked actuating device. This consequently may allow the output signal of

the two-hand control device to be generated by using only one hand. Suitable measures to prevent this

method of defeat are:

 To prevent reinitiation of the output signal for further operation by one hand, it shall be necessary to

include the characteristic of reinitiation in the design of the two-hand control device (see 5.6);

 To prevent the first start by one hand it shall be necessary to include the characteristic of synchronous

operation in the design of the two-hand control device (see 5.7).

NOTE Whenever the selection of a Type I two-hand control device is being considered it is important to carry out the

risk assessment carefully, to determine whether the characteristics of synchronous operation and of reinitiation can be

neglected
8.7 Accidental actuation

The probability of accidental actuation of a two-hand control device shall be minimised.

The measures given in 8.2 to 8.6 will help to minimise accidental actuation. Other suitable measures to

prevent accidental actuation are:

 For mechanical control actuating devices the need for deliberate actuation with respect to the force and

the travel required;

 For non-mechanical control actuating devices (e.g. photoelectric devices, capacitive devices) the need for

sensitivity levels which will only allow deliberate actuation.
---------------------- Page: 15 ----------------------
SIST EN 574:1998+A1:2008
EN 574:1996+A1:2008 (E)
9 General requirements
9.1 Ergonomic requirements

There will sometimes be a conflict between good ergonomic principles (see prEN 894) and the design of a

two-hand control device in order to prevent defeat or accidental actuation (e.g. the size of openings and the

need to wear gloves at some operations).
Means and measures to achieve safety need to reflect the balance between
 The need to follow good ergonomic principles, and;
 The need to provide measures to prevent defeat and accidental actuation.
The balance shall provide adequate safety for the particular risk.
9.2 Operating conditions, environmental influences

The parts of a two-hand control device shall be selected, installed and linked together in such a way that they

withstand the operating stresses to be expected and fulfil the requirements of the relevant standards (e.g. with

regard to switching capacity, switching frequency) and the relevant standards dealing with the environmental

influences to be expected (e.g. vibration, impact, temperatu
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.