Primary pressure valve, location/task/design/function - GF42.10-P-3101GG
MODEL 460, 461.217 /219 /223 /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 /401 /402 /403 /404 /405 /450 /451 /452 /454 /455 /456 /458 /459, 463
Task
To maintain a set pressure in the rear axle brake circuit after the braking process.
Special maintenance is not required.
Design
Function
The primary pressure valve (arrow) is screwed into the distributor in the brake line to the rear axle. After the brake is released, this valve maintains a primary pressure of 0.4 bar to 1.2 bar at the rear wheel brake.
When the brake is not operated, the primary pressure valve keeps the brake fluid in the lines permanently under pressure by means of the compression spring load. The slightest pressure increase when the brake is operated introduces an immediate braking effect, reducing the idle travel at the brake pedal.
Due to the pressure the lips of the wheel brake cylinder cup seals are pressed against the cylinder wall with greater tension and prevent the ingress of air.