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| Illustration 1 | g01001159 |
Insufficient pressure from piston pump (3) causes the contacts of pressure switch (9) to open. This sends a signal to the ECM which activates the electric drive pump (6) by connecting the electric drive pump to the battery.
If the steering wheel is stationary, oil is blocked at the metering pump. Pressure in the pump line moves valve (6a) which directs oil to the tank. The electric drive pump runs with less load and pressure is maintained in the pump line. Oil also flows through the load sensing line to the metering pump. Oil flows from the metering pump to the tank.
If the steering wheel is rotating, the gerotor pump, which is within the metering pump, transfers oil to steering cylinders (2) . A pressure increase in the load sensing line causes valve (6a) to move. This increases the pump output in order to satisfy the requirements of the system.
Illustration 1 shows oil flow from the electric drive pump while the machine articulates to the right.
Component Locations
For the location of the components, refer to Systems Operation, Testing and Adjusting, "Steering System".