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| Illustration 1 | g00843856 |
Electric hydraulic pump motor (1) for the secondary steering and gear pump (2) are located under the cab of the machine. | |
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| Illustration 2 | g00722933 |
Electric drive pump (secondary steering) (1) Electric hydraulic pump motor (secondary steering) (2) Gear pump (3) Diverter valve (4) Pressure relief valve | |
The secondary steering pump (2) is a gear type pump. The secondary steering pump is driven by an electric motor (1) that is controlled by the electronic control module (ECM). The secondary steering operates automatically when the machine is running and the pressure switch in the steering check and combiner valve indicates that the primary steering pump is no longer producing adequate pressure for steering.
A pressure switch in the check valve group in the steering system closes when the steering pressure falls below a set value for a certain duration. The switch sends a signal to the ECM. The ECM activates the electric motor that drives the pump at a constant speed.
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| Illustration 3 | g00718244 |
Switch (13) is located on left side of dash. | |
The ECM will also activate electric hydraulic pump motor (1) if switch (13) in the cab is pressed.
Diverter valve (3) and relief valve (4) are located in the pump casing.
To produce flow, the electric hydraulic pump motor is activated by the ECM. Motor (1) turns gear pump (2). Flow enters diverter valve (3). Flow is then directed to the steering check and combiner valve. Flow is directed to the metering pump (steering) from the steering check and combiner valve. Refer to Systems Operation, "General Information".
When gear pump (2) is in operation and the steering wheel is being turned, the flow then enters diverter valve (3). The flow creates a load sensing signal that is used to control the diverter valve and the flow is then directed to steering pump (12) to the flow compensator.
When the secondary steering is in operation, the pressure relief valve controls the maximum operating pressure of gear pump (2) .
When gear pump (2) is in operation and the steering wheel is not being turned, oil through the diverter valve is blocked at the steering check and combiner valve (22). Load sensing signal causes the diverter valve to move down. Flow to the secondary steering pump is directed to the inlet side of the gear pump.
No adjustment is provided for the diverter valve and no adjustment is provided for the pressure relief valve.