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