(Primary Pressure Valve, Location/Task/Design/Function - GF42.10-P-3101GG)
MODEL 460, 461.217/219/227/229/238/239/249/266/267/302/321/322/323/326/327/328/329/331/332/335/336/337/338/341/342/345/365/366/367/368/392/401/402/403/404/405/450/451/452/454/455/456/458/459, 463 up to 5/31/12
Location
The pilot pressure valve is screwed on to the brake line for rear axle at the distributor.
Task
To maintain a certain degree of pressure in the rear axle brake circuit after brake application.
A special maintenance service is not required.
Body
Function
After the brake is released, the pilot pressure valve maintains an initial pressure of 0.4 to 1.2 bar at the rear wheel brake. The brake fluid in the lines is thereby constantly under overpressure when the brake is not actuated. Even the slightest pressure increase at actuation causes an immediate braking effect. This reduces the free travel at the brake pedal. Apart from this, the overpressure causes the lips of the wheel brake cylinder boots to be pressed against the cylinder wall with higher force and the ingress of air is prevented.