ON TIMING BELT AND ROLLER CHAIN LOAD DISTRIBUTIONS

The research presented centers on determining the toothed belt load distribution of a toothed belt drive and the load distributions for a roller chain and sprocket in a roller chain drive. The effect of the material properties, frictional properties, and geometric proportions of the belt on the load distribution for the belt portion engaged with the pulley is studied. By the proper selection of the design parameters, a uniform load distribution among the engaged teeth can be obtained. Analytical results obtained from a finite difference analysis agree well with experimental results available in the literature.;Experimental load distribution results for a roller chain on nine different test sprockets are presented and are compared with analytical results obtained from a geometric Progression load distribution model and a spring model. Each model, for its region of applicability (which is based on the stiffness ratio of sprocket tooth and chain link), provides a good estimation of the load distribution. Due to friction between sprocket teeth and chain rollers, the load distribution for a chain on a driver sprocket differs from the load distribution for a chain on a driven sprocket. The geometric progression load distribution analytical model is modified by including centrifugal force on the chain and the pitch difference between the roller chain and sprocket. Chain link tensions, sprocket tooth loads, and plots of roller chain and sprocket interaction are given for several typical cases. Pitch difference can significantly effect load distribution; and in cases where the pitch difference is caused by wear elongation of the chain, the roller teeth loads are higher than those for the pin teeth.