When a flow request is reduced, or the engine torque limit is reached, the current sent to pumpcontrol solenoid valve (5) is reduced, causing the pump to DESTROKE. In Illustration 5, the pumpwas upstroked to provide oil flow at a high pressure and flow rate when the operator moved thecontrol lever to slow an implement function. The change in signal from the control lever positionsensor (joystick/pedal) indicating a lesser flow request, or when the pump torque control software isinvoked, the Machine ECM decreases the current to pump control solenoid (5).With less current to the solenoid, spring force moves the spool behind control solenoid valve (5) to aposition that directs pump discharge (4) pressure to the chamber behind actuator piston (8), butdrains away some of the existing system pressure through orificed passages within pressure controlvalve (2). The pressure differentials keep check valve (10) seated and the pressures separated. Whenthe pressure behind actuator piston (8) overcomes the force of bias spring (9), the piston movesswashplate (7) to a reduced angle. The pump is DESTROKED to produce less flow.The following conditions can result in DESTROKING the pump: All implement control valves are moved to the HOLD position. The control valve directional stem is moved to reduce flow. One or more circuits is/are deactivated. Engine rpm is increased. System pressure decreases for a given flow request and engine rpm. The engine torque limit is reached.In all the above cases (except torque limiting), the pump destrokes to match the system flowrequests. If the operator had moved the control lever to NEUTRAL (instead of stopping the function,as described), the pump would destroke to the STANDBY condition.
When a flow request is reduced, or the engine torque limit is reached, the current sent to pumpcontrol solenoid valve (5) is reduced, causing the pump to DESTROKE. In Illustration 5, the pumpwas upstroked to provide oil flow at a high pressure and flow rate when the operator moved thecontrol lever to slow an implement function. The change in signal from the control lever positionsensor (joystick/pedal) indicating a lesser flow request, or when the pump torque control software isinvoked, the Machine ECM decreases the current to pump control solenoid (5).With less current to the solenoid, spring force moves the spool behind control solenoid valve (5) to aposition that directs pump discharge (4) pressure to the chamber behind actuator piston (8), butdrains away some of the existing system pressure through orificed passages within pressure controlvalve (2). The pressure differentials keep check valve (10) seated and the pressures separated. Whenthe pressure behind actuator piston (8) overcomes the force of bias spring (9), the piston movesswashplate (7) to a reduced angle. The pump is DESTROKED to produce less flow.The following conditions can result in DESTROKING the pump: All implement control valves are moved to the HOLD position. The control valve directional stem is moved to reduce flow. One or more circuits is/are deactivated. Engine rpm is increased. System pressure decreases for a given flow request and engine rpm. The engine torque limit is reached.In all the above cases (except torque limiting), the pump destrokes to match the system flowrequests. If the operator had moved the control lever to NEUTRAL (instead of stopping the function,as described), the pump would destroke to the STANDBY condition.<br>
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