Electrical control for power shift transmission

Abstract

An electrical control provides output signals to a group of solenoid valves which control the gear ratio selected by a transmission. The electrical control receives input signals from a mode select lever, an upshift/downshift pulser lever, an engine RPM sensor, a ground speed sensor, a clutch position sensor switch, and a throttle control lever. The mode select lever has a neutral (N) position, a reverse (R) position, a forward manual (FM) position, and a forward automatic (FA) position. Movement of the mode select lever from N to FM causes the electronic control to actuate solenoid valves which select a first forward gear. Similarly, movement of the lever from N to R causes the control to actuate solenoid valves which provide a first reverse gear. Higher/lower gears are obtained by moving the upshift/downshift pulser lever from its normal position to either an upshift position or a downshift position. One upshift pulse causes the electronic control to actuate solenoid valves resulting in one gear shift upward. Holding the pulser lever forward in the upshift position gives sequential upshifts at predetermined time intervals. Pulsing or holding the pulser lever rearward in the downshift position has a reverse effect. When the forward automatic mode is desired, the operator first moves the mode select lever to FM and operates the pulser lever until the desired maximum gear has been attained. The operator then moves the mode select lever from the FM to the FA position. Thereafter the control upshifts and downshifts the transmission according to engine RPM and the desired throttle set point.