Function of damper valve - GF32.31-P-4300-02A

Diagrammatic view 

The reed valves(a.,b,c,d) each form one unit with a ball valve and throttle. 

4 different damping force stages can be achieved via the actuation by the ADS control module, suspension.

Damping force stage 1 

For comfortable running with small body movements and low longitudinal and lateral acceleration. In damping force stage 1 both solenoid valves y1 and y2 are open, which means the highest proportion of oil can bypass the reed valves. This achieves the Comfort  tension and pressure stage.

Damping force stage 2 

This is achieved by the reed valves on the valve piston. If the body moves downwards, solenoid valve y2 is opened and solenoid valve y1 is closed. The reed valves (a = pressure, hard and b = tension, soft) at the solenoid valve piston y1 cause a hard  pressure stage and a soft  tension stage.

Damping force stage 3 

This is achieved by the reed valves on the valve piston. If the body moves upwards, solenoid y1 is opened and solenoid valve y2 is closed. The reed valves (c = tension, hard and d = pressure, soft) at the solenoid valve piston y2 cause a hard  tension stage and a soft  pressure stage.

Damping force stage 4 (driving safety stage) 

For improved vehicle safety with high longitudinal and lateral accelerations of the vehicle. Both solenoid valves y1 and y2 are closed, the reed valves (a = pressure, hard and c = tension, hard) cause a hard  pressure and tension stage. This damping force stage is also switched if there is an ADS system fault and is displayed by the ADS MIL (A1e27), suspension in the instrument cluster.

Switching conditions of damping force stages 

Damping force stage	Damper valves (Y51 - Y54)		Valve control
	Tension stage	Pressure stage	Solenoid valve (y1)	Solenoid valve (y2)
1	Comfort	Comfort	Open	Open
2	Soft	Hard	Closed	Open
3	Hard	Soft	Open	Closed
4	Hard	Hard	Closed	Closed