Control system for powershift transmission clutches

摘要

A control system for a multi-speed powershift gear transmission having multiple hydraulically actuated speed range clutches and directional clutches includes a control valve module having solenoid operated valves for conducting pressure fluid to a selected one of the speed range clutches and a selected one of the directional clutches. A pressure regulator valve is in circuit with the directional clutch control valves and is acted on by pilot pressure fluid controlled by a proportional solenoid type control valve wherein the pressure rate of rise in the directional clutches may be selectively controlled in accordance with the particular shift condition initiated and based on a previous transmission operating condition. The control unit provides for a predetermined pressure rate of rise signal to the pressure regulator valve based on the selected shift condition and the previous operating condition of the transmission.