Abstract: A brake system for braking a rotatable brake disk includes a primary brake piston engagable with the brake disk and a secondary brake piston engagable with the primary brake piston and operable to move the primary brake piston into engagement with the brake disk. Both pistons are operable in response to fluid pressure. A primary brake valve controls communication of fluid pressure to the primary brake piston. A secondary brake valve controls communication of fluid pressure to the secondary brake piston.

Abstract: A method is provided for shifting a powershift transmission in a vehicle having an electronic engine control unit and an electronic transmission control unit. The method rapidly reduces off-going clutch pressure to a pressure which is slightly higher than a Predicted Off Slip Pressure, and rapidly increases on-coming clutch pressure P-on to a pressure that is slightly lower than a Predicted On Slip Pressure. Then, the method includes gradually decreasing P-off and gradually increasing P-on until slipping of the off-going clutch is detected, and gradually and more slowly decreasing P-off and gradually more slowly increasing P-on until the oncoming clutch begins to carry torque previously carried by the off-going clutch. Finally, the method includes more rapidly decreasing P-off to reservoir pressure, and more rapidly increasing P-on to a full on pressure.

Abstract: A method is provided wherein when an auxiliary device is being powered by the PTO driveline the PTO clutch is periodically slowly ramped down in pressure until slippage is detected in the clutch. Slippage is determined by monitoring the shaft speed into the clutch as well as the shaft speed downstream of the clutch. By determining the commanded pressure where slippage occurred, the equivalent engine power that is going to the auxiliary function is calculated. With this information, the proportion of the engine load signal that is going to the auxiliary function versus the drive wheels is determined. After slip is detected in the PTO clutch, pressure is ramped back up in the clutch so as to minimize the amount of slippage.

Abstract: A system and method are provided for monitoring a vehicle hydraulic system having a plurality of hydraulic function elements. The hydraulic system includes a hydraulic pump for supplying pressurized hydraulic fluid to the plurality of hydraulic function elements via a corresponding plurality of hydraulic element control valves, an electronic control unit for controlling the element control valves. The pump also supplies lube fluid to a lubrication circuit if requirements of the hydraulic function elements are met. The method includes sensing a hydraulic pressure (preferably the lube pressure of lube fluid in the lube circuit), and comparing the sensed pressure to a threshold pressure. If the sensed pressure is less than threshold pressure, then actively engaged hydraulic elements are tested by disengaging the elements in a predetermined manner, checking to see if the sensed low pressure condition is eliminated.

Abstract: A vehicle includes a powershift transmission driven by an electronically controlled engine. A control system momentarily modifies a magnitude of an engine throttle command signal during a shift of the power shift transmission in order to make the shift smoother and less sensitive to achieving optimum clutch engagement pressure. It also prevents an engine governor from over-reacting and causing rough shifts.