Abstract: The invention relates to power management of a off-highway vehicle. A power management apparatus is described as a vehicle control unit coupled to a vehicle and the vehicle control unit is in communication with an engine and a transmission controller. In response to power management input, the vehicle control unit sends a message to the transmission controller commanding a maximum torque limit based on the maximum drivetrain torque. The maximum torque limit is configured to optimize power to the vehicle implement.

Abstract: A vehicle powershift transmission has a lube oil passage which communicates lube oil to a clutch pack. Communication of lube oil is controlled as a function of the engagement state of the clutch pack. The hydraulic control pressure required to initially engage the clutch pack is determined or calibrated by a method wherein the lube oil pressure is monitored while the clutch control pressure is gradually increased. When the lube oil pressure reaches a certain level corresponding to clutch pack engagement, the current value of the control pressure is saved as the calibration pressure.

Abstract: A vehicle has a powershift transmission driven by an engine via a torque converter. The transmission is shifted by pressure operated clutches which are controlled by electrohydraulic pressure control valves. A speed ratio value representing a ratio of the torque converter output shaft speed to the torque converter input shaft speed is determined. A minimum clutch pressure value and a slope value are determined as a function of the speed ratio value. During a shifting of the transmission, a pulse-width-modulated signal applied to the valve is controlled so that the pressure applied to the clutch will vary from the minimum clutch pressure to a maximum clutch pressure at a rate proportional to the slope value.