When an implement function is requested (such as boom UP), the signal from the control leversensor is interpreted as a flow command. Depending on the function and the speed requested, theECM will send a current value to pump control solenoid valve (5) to move swashplate (7) to an anglethat will satisfy the flow demand, given the engine speed dial setting.As the implement control lever is moved, the signal from the control lever sensor causes the ECM toproportionally increase the current to pump control solenoid (5) according to the map for thatfunction. The increased current moves solenoid valve (5) to a position that blocks pump discharge(6) oil and drains the chamber behind actuator piston (8). This action allows bias spring (9) to moveswashplate (7) to an increased angle that satisfies the flow request. The pump UPSTROKES.When the swashplate reaches the angle that results in the requested (calculated) cylinder/motorspeed, the ECM adjusts the current to the solenoid to produce the CONSTANT FLOW condition.The following conditions can result in upstroking the pump: An implement control valve is activated when the system is at low-pressure standby. An additional circuit is activated. Engine rpm decreases. (In this case, pump rotational speed decreases which causes a decreasein flow and pump supply pressure. The pump must upstroke to maintain the system flowrequests.) When the torque limit strategy is in force and system pressure decreases.
When an implement function is requested (such as boom UP), the signal from the control leversensor is interpreted as a flow command. Depending on the function and the speed requested, theECM will send a current value to pump control solenoid valve (5) to move swashplate (7) to an anglethat will satisfy the flow demand, given the engine speed dial setting.As the implement control lever is moved, the signal from the control lever sensor causes the ECM toproportionally increase the current to pump control solenoid (5) according to the map for thatfunction. The increased current moves solenoid valve (5) to a position that blocks pump discharge(6) oil and drains the chamber behind actuator piston (8). This action allows bias spring (9) to moveswashplate (7) to an increased angle that satisfies the flow request. The pump UPSTROKES.When the swashplate reaches the angle that results in the requested (calculated) cylinder/motorspeed, the ECM adjusts the current to the solenoid to produce the CONSTANT FLOW condition.The following conditions can result in upstroking the pump: An implement control valve is activated when the system is at low-pressure standby. An additional circuit is activated. Engine rpm decreases. (In this case, pump rotational speed decreases which causes a decreasein flow and pump supply pressure. The pump must upstroke to maintain the system flowrequests.) When the torque limit strategy is in force and system pressure decreases.<br>
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