Friction and wear of synchronizers in hand–shifted transmissions

Abstract

The measurement of friction and wear on hand–shifted transmission synchronizers (highly loaded cone clutches) is carried out by two different test machines: 1. a steady state synchronization test stand: friction surface diameter: 40–80 mm; wear and the coefficient of friction are measured under steady state test conditions (i.e. axial force and speed are constant); 2. a non–steady state synchronization test stand: friction surface diameter: 90–170 mm; the synchronization process is simulated under the same non–steady state conditions as there are in a vehicle transmission; all parameters (for example axial force, speed, work and power loss due to friction) coincide on the test machine with those of a transmission in practical use; the synchronization process is measured and evaluated by plots. The friction surfaces are inspected by a stylus instrument (Perth–0–Meter) and by a scanning electron microscope. The influence of various parameters (for example friction materials, work and power loss due to friction, roughness and geometry of friction surface, lubricant, additive, etc.) on the friction and wear of the synchronizers can be determined. The methods of testing and the results obtained from the investigations will be presented in examples.