Deere & Company

Cooper Industries, Inc.

Jon R Patton

Robert W Harris

A transmission control system includes a plurality of hydraulic pressure operated control elements for engaging a gear of the transmission in response to actuation of a shift control lever having neutral and non-neutral positions, a plurality of control valves for controlling pressurization of the control elements and a pump for supplying pressurized fluid to the control valves. An engagement override system includes a switch which is coupled to the shift lever and which energizes a solenoid when the shift lever is in its neutral position and de-energizes the solenoid when the shift lever is in its non-neutral position. In a preferred embodiment, an engagement override valve includes a pilot operated valve which controls communication between the pump, a reservoir and the pressure operated control elements. The solenoid controls the pilot operated valve. The valve also includes a pilot chamber which is pressurized to move the valve to and hold the valve in a position wherein the pump is communicated with the pressure operated control elements.

Transmission engagement override valve

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.

Growing community of inventors

Coffeyville, KS, United States of America

Jon R Patton