ISO 9608:2022

Overview

ISO 9608:2022 - V-belts and V-ribbed belts - Uniformity of belts - Test method for determination of centre distance variation defines a standardized laboratory method to measure the centre distance variation (ΔE) of V-belts and V‑ribbed belt drives. The test quantifies non-uniformities that cause force fluctuations and irregular running of belt drives. Note: the standard explicitly does not apply to elastic V-ribbed belts.

Key topics and requirements

• Measurement principle: two identical grooved pulleys, one movable under a specified measuring force (F), the other rotating at a controlled low speed.
• Belt speed limit: belt speed shall not exceed 1 m/s during measurement.
• Measured quantity: centre distance (E) between pulley axes; centre distance variation (ΔE) is the difference between the maximum and minimum centre distance measured on the standardized fixture (ΔE = Emax − Emin).
• Measurement accuracy: centre distance variation can be measured with an accuracy of 0.05 mm.
• Procedure summary:
  • Seat the belt correctly in pulley grooves and apply the specified measuring force.
  • Rotate the pulleys at least two complete revolutions to divide force equally between belt spans.
  • During a subsequent revolution record Emax and Emin and calculate ΔE.
• Test report requirements: reference to ISO 9608, centre distance variation rounded to two decimal places, belt type/profile/technical design and date of manufacture.
• Specifications for pulleys and measuring forces: given in corresponding belt standards (see Related Standards).

Practical applications

• Quality control of V-belts and V-ribbed belts during production acceptance testing.
• Comparative uniformity testing for supplier qualification and incoming inspection.
• Root-cause analysis for belt-drive vibration, noise and irregular running in manufacturing or vehicle systems.
• R&D and product development to validate belt design and manufacturing consistency.
• Maintenance and reliability engineering to assess belt condition and performance variability.

Who should use this standard

• Belt manufacturers and test laboratories
• OEMs specifying belts for industrial machinery or automotive applications
• Quality assurance teams and incoming inspection personnel
• Design engineers and maintenance teams working on belt-drive systems

Related standards

ISO 9608 references groove and belt specifications in related ISO documents for measuring pulleys and forces, including:

• ISO 1081 (vocabulary)
• ISO 1604, ISO 2790, ISO 3410, ISO 4184, ISO 5289, ISO 8419 (V-belt types)
• ISO 9981, ISO 9982 (V-ribbed belt profiles)

Using ISO 9608:2022 helps ensure consistent, repeatable measurement of belt uniformity and supports reliable, low-vibration belt-drive performance.