THEORY OF OPERATION - CONTINUED
STEERING SYSTEM - CONTINUED
Secondary steering valve is located on upper left frame above secondary steering pump and electric motor.
Steering metering pump is attached to bottom of steering column, and located under floor of operator's
Steering control valve is located below operator's cab, between engine and cab.
During normal machine operation, left check valve is off seat, while right check valve is seated. Right
check valve prevents pressure oil from flowing back to secondary steering pump.
If steering pump fails or engine fails, primary steering pressure switch changes state due to low oil pres-
sure in steering system. Primary steering pressure switch sends a signal to monitoring system, which trig-
gers an alarm.
Alarm alerts operator that engine shutdown should occur as soon as possible. This helps prevent injury to
personnel and potential damage to machine. Do not operate machine until cause of failure has been cor-
After a one-second delay, relay for secondary steering pump actuates and secondary steering indicator illu-
Secondary steering pump draws oil from hydraulic oil tank. Oil then flows to secondary steering valve,
causing right check valve to unseat. Oil pressure then causes left check valve to seat, preventing pressure
oil from flowing back to steering pump. Oil pressure then flows to steering control valve.
Oil pumped from secondary steering pump causes secondary steering pressure switch to change state, acti-
vating secondary steering indicator.
N OT E
The machine can be articulated during the three-second engine start-up test.
Condition of secondary steering is tested during engine start-up. During three-second test, secondary steer-
ing indicator illuminates and action alarm sounds. This verifies steering system is pressurized.
Secondary Steering Pump and Electric Motor.