Importance

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Abstract

A control circuit is disclosed for automatic lockup of a torque converter in the driveline of a work vehicle. The primary control for engaging the lockup clutch is a speed signal corresponding to the speed of the output shaft of the torque converter. A speed responsive signal generator produces a lockup signal at a first set-point when the torque demand is at a higher value and has a lower speed set-point for producing a lockup signal when the torque demand is at a lower value. A transmission responsive signal generator produces an enabling signal for torque converter lockup when the transmission is in forward drive above the first speed range. Shift of the transmission from one drive range to another produces a momentary disenabling signal to cause the lockup clutch to be disengaged and minimize driveline shock. Overspeed signal generator produces a disenabling signal to cause disengagement of the lockup clutch in an overspeed condition.

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First Claim