GENERATOR G. 1L4589 - Caterpillar

Horsepower Control
Illustration 13 g00955560
Constant flow (Horsepower control) (1) Horsepower control spool (3) Load sensing spool (4) Load sensing damper hose (6) Power shift pressure (9) Lever (10) Power shift piston (11) Minimum angle piston (12) Actuator piston (13) Maximum angle piston (15) Signal limiter valve (16) Main relief valve (17) Load sensing signal (18) Main control valve (19) Signal dump valve (20) Throttle pin (22) Sensor (23) Pump supplyIf system pressure and the pump flow does not affect horsepower control spool (1), load sensing spool (3) will control the pump.As the pump upstrokes and as the pump destrokes actuator piston (12) moves along lever (9) .When the pump upstrokes, actuator piston (12) moves farther away from the pivot pin and the mechanical advantage increases. The force that is working on lever (9) will also increase with an increase in system pressure if the pump is in a state of constant flow.When the force that is working on lever (9) overcomes power shift pressure (6) that is acting on the power shift piston (10), the power shift piston and horsepower control spool (1) shift and take over control of the pump flow.Destroke (Horsepower Control)
Illustration 14 g00955575
Destroke (Horsepower control) (1) Horsepower control spool (3) Load sensing spool (4) Load sensing damper hose (6) Power shift pressure (9) Lever (10) Power shift piston (11) Minimum angle piston (12) Actuator piston (13) Maximum angle piston (15) Signal limiter valve (16) Main relief valve (17) Load sensing signal (18) Main control valve (19) Signal dump valve (20) Throttle pin (22) Sensor (23) Pump supplyWhen the increased force that is working on lever (9) is able to overcome power shift pressure (6), shown in Illustration 14, lever (9) pivots against the force of power shift pressure (6) and the spring on the right side of power shift pressure piston (10). The spring force on the left end of horsepower control spool (1) moves the spool to the right.Horsepower control spool (1) directs pump supply pressure oil past load sensing spool (3) to minimum angle piston (11). The pump supply pressure in minimum angle piston (11) and the spring force are able to overcome maximum angle piston (13) and the spring force in order to move the swashplate to a reduced angle, which reduces the flow.Once horsepower control spool (1) takes control of the pump flow, horsepower control spool (1) will further destroke the pump due to either an increase in the system pressure or a decrease in power shift pressure (6) .The decrease in power shift pressure (6) can be caused by either lugging of the engine or a change in the power mode.As the pump destrokes, actuator piston (12) moves closer to the pivot point of the lever (9). As actuator piston (12) moves closer to the pivot point, an increased system pressure is needed to overcome the mechanical advantage of lever (9) and power shift pressure (6) .Initially, the pump is destroked faster, but the system pressure is increased. The pump is destroked more