MODEL | 967 |
Location
Shown on vehicle with code A1A (Air-sprung front axle) |
Y20 | Front axle level control valve unit |
W32.33-2091-81
The front axle level control valve unit (Y20) is installed in the center on the frame crossmember in the area of the fuel tank.
Task
The front axle level control valve unit (Y20) converts the control signals from the level control (CLCS) control unit (A26) into air-admission and venting procedures for the sleeve air springs (43.01) of the front axle.
Body
Components/pneumatic connections |
3 | Atmospheric connection (venting) |
11 | Energy supply (air suspension reservoir pressure) |
22 | Energy outflow (right sleeve air spring) |
23 | Energy outflow (left sleeve air spring) |
ANV 1 | Pneumatic starting-off valve 1 (electrically actuated) |
ANV 2 | Pneumatic starting-off valve 2 (electrically actuated) |
DR | Throttle |
F | Filter |
WV | 3/2-way valve |
WV1 | 2/2-way valve 1 |
WV2 | 2/2-way valve 2 |
Y20 | Front axle level control valve unit |
W32.33-2065-11
The 2/2-way valves (WV1, WV2) or the 3/2-way valve (WV ) are directly connected to the level control control unit (CLCS) (A26).
Function
1 Increase in pressure at energy outflows (22, 23)
Pneumatic starting-off valve 1 (electrically actuated) (ANV 1) of the 3/2-way valve (WV) is energized which causes the 3/2-way valve (WV) to switch to the flow-through position. The pressure present at the energy supply (11) is fed to the 2/2-way valves (WV 1 and WV2) which are in the closed position. Pneumatic starting-off valve 2 (electrically actuated) (ANV 2) of the 2/2-way valves (WV 1 and WV2) is then energized and the 2/2-way valves (WV 1 and WV 2) switch to the flow-through position. The pressure present at the input of the 2/2-way valves (WV 1 and WV WV2) is fed to the energy outflows (22 and 23). If the desired pressure is not achieved at the energy outflows (22 and 23), the pneumatic starting-off valve 2 (electrically actuated) (ANV 2) is no longer energized and the 2/2-way valves (WV 1 and WV 2) switch back to locking position. The pressure present at the energy outflows (22 and 23) is held.
2 Reduction in pressure at energy outflows (22, 23)
In order to reduce the pressure at the energy outflows (22 and 23), pneumatic starting-off valve 1 (electrically actuated) (ANV 1) is no longer energized and the 3/2-way valve (WV) switches back to its starting position. Pneumatic starting-off valve 2 (electrically actuated) (ANV 2) of the 2/2-way valves (WV 1 and WV2) is energized and the 2/2-way valves (WV 1 and WV 2) switch to the flow-through position. The pressure present at the energy outflows (22 and 23) is then vented via the 2/2-way valve 1 (WV 1) or 2/2-way valve 2 (WV 2), the 3/2-way valve (WV) and the atmosphere connection (3). If the desired pressure is not achieved at the energy outflows (22 and 23), the pneumatic starting-off valve 2 (electrically actuated) (ANV 2) is no longer energized and the 2/2-way valves (WV 1 and WV 2) switch back to locking position. The pressure present at the energy outflows (22 and 23) is held.