Abstract: A method and apparatus for determining a value of torque at a desired location on a machine. The method and apparatus includes choosing the desired location, determining an operating condition relevant to the desired location, determining a plurality of parameters of the machine, and determining a value of torque at the desired location as a function of the operating condition and the plurality of parameters.

Abstract: A method and apparatus for determining a value of torque at a desired location on a machine. The method and apparatus includes choosing the desired location, determining an operating condition relevant to the desired location, determining a plurality of parameters of the machine, and determining a value of torque at the desired location as a function of the operating condition and the plurality of parameters.

Abstract: In one aspect of this invention, a system and process for controlling a fluid actuated retarder is disclosed. This includes an input mechanism and an electronic controller for receiving a signal from the input mechanism, including a value for a desired retarder control level. Also, there is a proportional solenoid valve that is actuated by the electronic controller. The proportional solenoid control valve is operatively connected to a proportional retarder spool valve and the proportional retarder spool valve is operatively connected to a fluid actuated retarder.

Abstract: A default mode control system for controlling a split torque transmission is disclosed. The default mode control system monitors various inputs to the control to detect an on board electrical, electronic fault or mechanical, hydraulic fault. When a fault is detected, the default mode control will recover from the default and then will limit operation of the split torque transmission based on the fault input.

Abstract: In machines such as hauling units having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission remains in one of its gear ratios. In the subject invention, a dependent latching system is provided in a transmission which in the event of an electrical malfunction latches the transmission in the existing gear ratio or a gear ratio within at least two gears ratios. This is accomplished by providing a master latch valve mechanism, a logic valve arrangement, and a latching shuttle valve to act in cooperation with an electrically controlled proportional valve and a hydraulic proportional valve that controls engagement of a plurality of hydraulically actuated clutches. The master latch valve mechanism directs pressurized fluid from a source of pressurized fluid through the logic valve to urge the latching shuttle valve to an open position.

Abstract: In machines such as hauling units having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission remains in the gear that it was in when the electrical malfunction occurred. In the subject invention, an independent latching system is provided in a transmission which in the event of an electrical malfunction automatically latches the transmission in the existing gear. This is accomplished by providing a master latch valve mechanism and a latching shuttle valve to act in cooperation with an electrically controlled proportional valve and a proportional valve that controls engagement of a plurality of hydraulically actuated clutches. When the transmission is operating normally, the master latch valve mechanism directs pressurized fluid from a source of pressurized fluid to urge the latching shuttle valve to an open position.

Abstract: A control system is provided for a vehicle regulating engine speed during shifts so as to reduce driveline torque and shift shock. The control system includes separate microprocessor based engine and transmission controllers which communicate via a data link. When a shift is initiated, the transmission controller delays a first period of time CTSDELAY sufficient for the transmission to disengage the old gear ratio and then produces a CTSSPEED signal. The transmission controller continues to produce the CTSSPEED signal for a second period of time CTSDUR which corresponds to the time required for the transmission to engage the new gear ratio. The engine controller receives the desired engine speed signal and regulates engine speed into correspondence with the desired speed. During upshifts, the CTSSPEED signal is set to a speed which is a predetermined amount above the synchronization speed of the new gear for an upshift.

Abstract: Flow-pressure compensated valves are employed in servo-systems for variable displacement pumps to maintain discharge pressure above a minimum pressure level and above the load pressure in a fluid actuator, during the working range of the pumps. In addition, such systems may also include a horsepower limiting valve for ensuring that the rating or predetermined range of horsepower consumption of the pumps is not exceeded. Prior art systems normally continually bleed-off pump discharge or load pressure signals when such horsepower requirements are exceeded to, thus, effect an undesirable horsepower loss in the system. In addition, control systems of this type normally cannot be packaged in modular form and are not adapted for use with pumps of various capacities and sizes. The improved fluid circuit (10) of this invention includes a horsepower limiting arrangement (39) for blocking communication of an actuator pressure signal (P.sub.

Abstract: A pump control assembly for a variable displacement pump has a means connected to a spring for selectively adjusting the preload on the spring for selectively adjusting the minimum pump discharge pressure. An adjustable stop device is provided for selectively adjusting the maximum force exerted on the spring by a piston device which increases the load on the spring for increasing the pump discharge pressure in response to a load pressure signal exceeding a preselected pressure level.

Abstract: A first device for controlling the position of a displacement control member of a variable displacement pump has an actuator connected to the control member and a valve member which is movable between a first position at which a pump discharge pressure signal is in communication with the actuator and a second position at which said pump discharge pressure signal is blocked from communication with the actuator and the actuator is connected to a drain. The valve member has an end substantially continuously exposed to the pump discharge pressure signal and is responsive thereto for biasing the valve member toward one of the first and second positions. A spring apparatus biases the valve member toward the other of said positions in opposition to the biasing force of said pump discharge pressure signal and establishes a preselected minimum discharge pressure.