Lubricant Optimisation for Synchromesh Manual Transmission of Utility Vehicles 2008-01-1710
In general the mechanical design and function of synchronized manual transmissions has remained relatively constant over the years, with incremental improvements in components, gears, bearings, seals, synchronizers and fluids continuing to advance the quality of the overall product.
Marketplace demands generally drive improvements which are primarily aimed at durability and shift quality. Recently, however, advances in control and actuation technology have led to a new generation of automated manual transmissions. As a result, compatibility with electronic and valve components is becoming increasingly important. The synchronizers and fluid are two components that can affect the overall transmission performance experienced by the end user.
Historically, there has been a variety of synchronizer materials, primarily brass for smaller vehicles such as passenger cars and molybdenum-based products for larger commercial vehicles. Recently sinter compositions, carbon and also phenolic materials have been used although mostly in Japan. Each composition affords the designer different wear and durability properties(1). For example, although sinter is a copper-based alloy like brass the fluid does not always respond to each in the same way. Thus, there is a need to revise the fluid composition to obtain the optimum performance with the synchronizer material being used.
This paper studies the effect of fluids on the friction performance of the brass synchronizer materials used by one of India's leading original equipment manufacturers (OEM), Mahindra and Mahindra, during bench and vehicle testing. This paper also includes a range of key laboratory tests that provide a relative assessment of product performance.