ISO 155:2019

Belt drives - Pulleys - Limiting values for adjustment of centres

This document specifies the limiting values for the adjustment of centres of two transmission pulleys. It is applicable to: - crowned pulleys for flat belts; - grooved pulleys for V-belts, either single, multiple or joined; - grooved pulleys for V-ribbed belts; - toothed pulleys for synchronous belts.

Transmissions par courroies — Poulies — Limites de réglage d'entraxe

General Information

• Status: Published
• Publication Date: 25-Mar-2019
• ICS: 21.220.10 - Belt drives and their components
• Technical Committee: ISO/TC 41/SC 1 - Friction
• Drafting Committee: ISO/TC 41/SC 1 - Friction
• Current Stage: 9093 - International Standard confirmed
• Start Date: 25-Sep-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 155:1998 - Belt drives - Pulleys - Limiting values for adjustment of centres
• Effective Date: 16-Jan-2016

Overview

ISO 155:2019 is an international standard developed by the International Organization for Standardization (ISO) that specifies the limiting values for the adjustment of centres of two transmission pulleys in belt drive systems. This fourth edition of the standard replaces the previous 1998 version with technical revisions and editorial clarifications.

Applicable to various types of pulleys-including crowned pulleys for flat belts, grooved pulleys for single, multiple or joined V-belts, V-ribbed belts, and toothed pulleys for synchronous belts-ISO 155:2019 defines the precise center distance tolerances necessary for optimal belt drive performance. These limits ensure appropriate belt tension, reduce wear, and increase transmission reliability.

Key terms such as the adjustment limits for centre distances, as well as factors impacting these limits, are detailed to assist engineers and designers with the correct specification and installation of belt drives in machinery.

Key Topics

• Scope and Applicability
  ISO 155:2019 covers limiting values for adjustments in center distances between two pulleys in belt drives, relevant to:

  • Crowned pulleys for flat belts
  • Grooved pulleys for classical, narrow, and joined V-belts
  • Grooved pulleys for V-ribbed belts
  • Toothed pulleys for synchronous belts

• Limiting Values and Adjustment Factors
  The standard specifies lower and upper limits for center distance adjustment as functions of nominal distance and defined factors:

  • Factor i relates to pulley dimensions and tolerances as well as belt length tolerances (used for slack-off).
  • Factor s incorporates pulley dimension tolerances, belt length tolerances, flat pulley crowning, and belt elasticity (used for take-up).

• Dimensional Tables and Tolerances
  Comprehensive tables provide specific values for:

  • Diameter tolerances of flat pulleys
  • Datum and effective widths for V-belts
  • Groove pitch values for V-ribbed belts
  • Values of adjustment factors based on belt types and materials

• Material Considerations
  Belt material properties influence elastic factors impacting take-up adjustments, with values provided for various tensile member materials including polyamide, polyester, aramid, glass fiber, and metal.

• Calculation Formulas
  The standard includes formulas for calculating cumulative factors and limiting adjustments critical for design and maintenance applications.

Applications

ISO 155:2019 is essential for professionals involved in the design, manufacture, installation, and maintenance of belt-driven machinery across various industries such as manufacturing, automotive, agriculture, and industrial equipment. Practical applications include:

• Machinery Design
  Defining minimum center distances to ensure proper belt tensioning during installation and operation.
• Belt Drive Installation
  Ensuring the correct center distance adjustment range to accommodate belt slack-off and take-up periods without compromising belt or pulley integrity.
• Maintenance and Troubleshooting
  Establishing guidelines for re-tensioning and checking center distances to prolong belt life and maintain efficiency.
• Quality Control
  Standardizing belt and pulley manufacturing and assembly tolerances to maintain interchangeability and performance consistency.

By adhering to ISO 155:2019, manufacturers and engineers can optimize power transmission efficiency, reduce downtime, and extend the operating life of belt drive systems.

Related Standards

ISO 155:2019 works in conjunction with several related ISO standards that address complementary aspects of belt drives and pulleys:

• ISO 22 – Flat transmission belts and corresponding pulley dimensions and tolerances
• ISO 4183 & ISO 4184 – Classical and narrow V-belts with grooved pulleys and length systems
• ISO 5290 & ISO 5291 – Grooved pulleys for joined narrow and classical V-belts
• ISO 8419 – Narrow V-belts dimensional specifications
• ISO 9982 – Grooved pulleys and V-ribbed belts for industrial use
• ISO 13050:2014, ISO 17396:2017, ISO 19347:2015 – Standards for synchronous belt drives including metric and imperial pitch systems

These complementary standards ensure consistency across belt and pulley system specifications, facilitating engineering design and global interoperability.

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ISO 155:2019 provides critical guidelines and detailed data for effective center distance adjustment between pulleys in belt drives, supporting efficient power transmission and operational reliability across a broad range of applications. Adoption of this standard ensures best practices in mechanical drive design and maintenance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 155
Fourth edition
2019-03
Belt drives — Pulleys — Limiting
values for adjustment of centres
Transmissions par courroies — Poulies — Limites de réglage
d'entraxe
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Specifications . 2
6 Factors . 3
Bibliography . 6
Foreword
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 41, Pulleys and belts (including veebelts),
Subcommittee SC 1, Friction.
This fourth edition cancels and replaces the third edition (ISO 155:1998), which has been technically
revised. The main changes compared to the previous edition are as follows:
— adding of curvilinear sections to Table 6;
— editorial clarifications of the document.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 155:2019(E)
Belt drives — Pulleys — Limiting values for adjustment
of centres
1 Scope
This document specifies the limiting values for the adjustment of centres of two transmission pulleys.
It is applicable to:
— crowned pulleys for flat belts;
— grooved pulleys for V-belts, either single, multiple or joined;
— grooved pulleys for V-ribbed belts;
— toothed pulleys for synchronous belts.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Symbols
For the purpose of this document, the following symbols apply.
Symbol Definition Unit
d ± δ Limits of small flat pulley diameter mm
D ± δ Limits of large flat pulley diameter mm
e Groove pitch of a V-ribbed pulley mm
E Nominal centre distance mm
E - i Lower limit for the adjustment of centre distance mm
...