Electro-Hydraulic Controlled Transmission for Mid Size Agricultural Tractors

This paper describes a new technology of an electronically controlled transmission for mid-size agricultural tractors.

The most notable feature is a electro hydraulically controlled wet multi-disk clutch that is employed to change transmission speeds. This clutch provides for continuous, smooth speed changes regardless of load. The speed change is accomplished by three steps of control: 1) overlap control where the pressure applied to the hydraulic clutch is overlapped, 2) load detection control where the load is determined by monitoring the engine rpm and the governor setting, and 3) shock reduction control where the hydraulic clutch pressure is reduced according to the load.