Clutch engagement modulation to control acceleration.

摘要

In a tractor transmission system having electro-hydraulically actuated powershift clutches (C1-C4) and a forward/reverse coupler (25) mechanically coupled to a forward/reverse lever (100), a dump button (118) is provided on the lever (100) for releasing powershift clutch pressure. The forward/reverse coupler (25) is uncoupled from the transmission input and output shafts (10, 11) when the button (118) is depressed. An operator may shift between forward and reverse gears by depressing the button (118) and shifting the lever (100). Upon release of the dump button (118), a microprocessor (80) performs a control algorithm during which it senses engine speed and ground speed, computes acceleration/deceleration, and controls the clutch pressure of one of the powershift clutches (C1-C4) to provide smooth acceleration in the direction selected by the shift lever (100). The arrangement is particularly suited for shuttle shift (forward/reverse) operations but may be used to provide smooth acceleration from a stopped position. Smooth acceleration is obtained regardless of the tractor weight and load and operation of a clutch pedal (78) is not required. The control algorithm is equally suitable for controlling full powershift transmissions or synchronized shuttle transmissions having no powershift clutches.