Abstract: An apparatus for limiting the power output of a hydraulic system is disclosed. The hydraulic system has a variable displacement pump. The variable displacement pump has a movable swashplate and is driven by a source of motive power. The apparatus includes a memory device for storing a set of power modes. Each power mode has a predetermined power level associated with the hydraulic system and is defined by a plurality of set points. Each set point corresponds to a predetermined flow rate and discharge pressure of the pump. A device senses the speed of the source of motive power and producing a signal representative of the actual speed in response to the sensed speed. A device senses the pressure of the variable displacement pump and produces a signal representative of the actual pressure in response to the sensed pressure. A device senses the swashplate angle of the variable displacement pump and delivers a signal representative of the actual swashplate angle in response to the sensed swashplate angle.

Abstract: High pressure cutoff controls are useful for variable displacement hydraulic pumps for reducing power losses at high pressure levels. Some operators, however, believe that they get more work from pumps not having the high pressure cutoff control. The subject on-off high pressure cutoff control includes an on-off valve disposed in a pilot passage connected to an output port of a pump and to an end of a high pressure cutoff valve. The on-off valve is selectively movable between a first position at which pressurized fluid passes through the pilot passage to the end of the high pressure cutoff valve to prevent it from functioning as a high pressure cutoff valve. Thus, an operator has the option of operating the hydraulic pump with or without the high pressure cutoff control.

Abstract: An apparatus controls a fluid system of a work vehicle. The work vehicle has an engine and at least one fluid circuit which has a pump driven by the engine. A plurality of control valves controllably pass fluid from the pump to a plurality of respective work elements. The control valves have movable valve stems. A work attachment which has a respective control valve is added to the fluid system. A plurality of operator control elements provide demand signals in response to selected settings. Each demand signal is indicative of a requested fluid flow to a respective work element or work attachment. A memory device stores select parameters of the fluid system. One of the select parameters is a predetermined priority value representing the precedence in which fluid is delivered from the pump to the control valve of the work attachment. A controller receives the predetermined priority value of the work attachment and the demand signals.