Simulating Synchroniser Stick-Slip Behaviour for Superior Gearbox Performance

OEMs strive to obtain greater mechanical efficiency from their transmissions. It is widely accepted that this can be achieved by reducing the bulk viscosity of the transmission fluid, which reduces the churning losses responsible for a considerable amount of the inefficiency. There is ever-increasing demand on the transmission fluid to maintain or even increase the durability of the transmission components. However, the resulting loss of film thickness due to the lower viscosity fluid produces ever more arduous operating conditions for the transmission components, which rely on strong multifunctional additive packages not only to maintain durability but also to control the contact mechanics. This paper describes the development of a novel bench-top, friction screening test used to gain valuable fundamental knowledge and guide the formulation of manual transmission fluids (MTF) with tailored and controlled frictional performance.