V-RIBBED BELT DESIGN, WEAR AND TRACTION CAPACITY

Laboratory dynamometer experiments have been performed on the running- in of an automotive K-section V-ribbed belt. The rib shape has been fo und to change, owing to wear, in three regions. At the top of the rib, a shoulder develops; at the root of the rib, debris piles up; in betw een, the rib wears without change of slope. The main changes occur in the first 20 h of running-in conditions chosen to represent loads foun d in practice; after running for 250 h, further changes could hardly b e observed. The measured rib profiles were input to finite element cal culations of the contact pressures between the ribs and the pulley gro oves. The purpose was to study the way in which load was shared betwee n the rib flanks and the rib roots and further to study the reduction in traction capacity of the belt due to increased root loading as wear progressed. After running for 250 h, the belt was estimated to have a bout a 10 per cent lower maximum traction coefficient than when it was new. An improved belt design is suggested, to enable high traction ca pacity to be maintained for longer times.