The Hydrodynamic Phase of Gearbox Synchromesh Operation

Abstract

The approach used is to divide the synchronization process into three distinct stages according to the friction regime operating, this idea being closely allied to that of A. E. Anderson (1972, SAE paper 750521). The authors proceed to derive a model for the first stage based on a shaft-ring pair with or without taper defects (angular mismatch). Expressions are derived for contact pressure (and hence axial force), output torque and the coefficient of friction, the latter pair being arrived at by considering the shear stresses acting at the cone surface. The results that are gained allow best and worst cases of torque and friction to be considered and the effect of circumferential grooves and axial slots to be theoretically examined, and the potential for this model in simulating such configurations is discussed. The main conclusion of the paper is that the coefficient of friction clearly decreases during the first stage such that the value during the second stage may be quite small (results of the analyses of the second and third stages are promised for the future), but it is now relatively simple to estimate this with acceptable accuracy.