Operation Principle

During Parking (When Turning The Steering Wheel To The Right.) 

Fig 1: Operation Principle - During Parking (When Turning Steering Wheel To Right.)

Courtesy of NISSAN MOTOR CO., U.S.A.

1. Power steering solenoid valve is closed while a vehicle is stopped.
2. Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
3. Oil pressure "P" in the gear housing assembly is the sum of oil pressures occurring in "2R" and "3R". This results in a light steering force because of high pressure.

During High-speed Operation 

Fig 2: Operation Principle - During High-Speed

Courtesy of NISSAN MOTOR CO., U.S.A.

1. Power steering solenoid valve is opened during high-speed operation.
2. Pinion "1R", "2R" and "3R" are closed depending on steering torque of steering wheel.
3. "2R" is bypassed to the return port by the EPS solenoid valve.
4. Oil pressure "P" in the gear housing assembly includes only oil pressure occurring in "3R" and results in a heavy steering force.