Speed-sensitive power steering, steering angle, function - GF46.50-P-2300CW

MODEL 204.0/2 with CODE (213) Speed-sensitive power steering up to Model Year 8 

Shown on left wheel lock 

General function 

If the steering wheel is turned, then the drive pinion is supported on the toothed rack. The rotary valve is twisted against the pilot bushing surrounding it via the stabilizer bar and this changes the position of the control grooves in relation to one another. The pressure oil flow now reaches the right working cylinder (left wheel lock) or the left working cylinder (right wheel lock) and causes the axial movement of the gear rack to the right or left.

The oil from the unpressurized working cylinder is displaced. It flows back into the power steering pump reservoir via the open non-return grooves of the pilot bushing.

Steering force support is regulated to match vehicle speed. Regulation is effected over the speed-sensitive power steering solenoid valve, which is actuated by the Electronic Stability Program control unit (N30/4) in a speed-dependent manner.

A differentiation is made here between the following conditions:

• Vehicle speed v = 0 km/h
• Vehicle speed v >0 km/h and 100 km/h
• Vehicle speed v >100 km/h

Vehicle speed v= 0 km/h (shown on left steer) 

Function with vehicle speed v = 0 km/h 

The speed-sensitive power steering solenoid valve receives maximum energy and as a result it is closed against the force of the integrated compression spring. The pressure ratios in the reaction chambers are identical since the supply of oil is stopped. No force is applied to the reaction balls, no additional moment arises on the surfaces of the rotary valve.

Vehicle speed v > 0 km/h and  ≤ 100 km/h (shown on steering left) 

The steering is light, as the steering torque applied by the driver, consisting of overcoming the force of the torsion bar, is very low. Via the constant constriction orifice the oil flow is passed on to the power steering pump reservoir virtually depressurized.

Function at vehicle speed v > 0 km/h and ≤ 100 km/h As vehicle speed increases the supply to the speed-sensitive power steering solenoid valve decreases continuously, this is opened by the force of the integrated compression spring. The controlled pressure is lead to the reaction balls via the regulating valve which causes the pressure applied to the surfaces of the rotary valve to increase.

The force on the torsion bar is increased further as a result and the driver has to operate the steering wheel with a higher steering torque. The constant constriction orifice reduces the regulated pressure from the speed-sensitive power steering solenoid valve. This is then passed on as an almost depressurized backflow to the power steering pump reservoir.

Vehicle speed v >100 km/h (shown steering left) 

Function with vehicle speed v > 100 km/h 

The speed-sensitive power steering solenoid valve receives minimum energy. As a result maximum pressure is routed from the speed-sensitive power steering solenoid valve to the reaction balls via the regulating valve, which in turn causes the pressure applied to the surface of the rotary valve to increase to a maximum.

The constant constriction orifice reduces the regulated pressure from the speed-sensitive power steering solenoid valve. This is then passed on as an almost depressurized backflow to the power steering pump reservoir.

	Steering gear of rack-and-pinion steering, component description		GF46.20-P-5137CWA
	Power steering pump, component description		GF46.30-P-5136CW
	Electronic Stability Program control unit component description	N30/4	GF42.45-P-5119CW
	SPS [PML] solenoid valve, component description	Y10	GF46.50-P-5140CW