Abstract: A closed level control system includes an air dryer (10) which is mounted in a pressurized air line (4). The compressor output (16) can be connected to the pressurized air supply vessel (12) via the pressurized air line (4). Air from the atmosphere can be transferred via an intake valve (30) into the pressurized air supply vessel (12) via the compressor and the air dryer (10). Furthermore, pressurized air can be discharged into the atmosphere from the pressurized air supply vessel (12) via the air dryer (10) and the intake valve (30). There is a flow in the opposite direction through the air dryer than when filling the pressurized air supply vessel (12) from the atmosphere. In this way, an excellent regeneration of the air dryer (10) is ensured.

Abstract: A closed level control system includes an air dryer (10) which is mounted in a pressurized air line (4). The compressor output (16) can be connected to the pressurized air supply vessel (12) via the pressurized air line (4). Air from the atmosphere can be transferred via an intake valve (30) into the pressurized air supply vessel (12) via the compressor and the air dryer (10). Furthermore, pressurized air can be discharged into the atmosphere from the pressurized air supply vessel (12) via the air dryer (10) and the intake valve (30). There is a flow in the opposite direction through the air dryer than when filling the pressurized air supply vessel (12) from the atmosphere. In this way, an excellent regeneration of the air dryer (10) is ensured.

Abstract: The invention relates to a level control arrangement for vehicles having air springs (6a) to (6d) and a pneumatically controllable directional valve (26). A residual pressure holding function and an overpressure function are integrated into the directional valve (26). The directional valve (26) is controlled by the air pressure in the air springs (6a) to (6d). The air pressure can be applied via a control line (20) to a control input (24) of the directional valve (26). The air from the air springs (6a) to (6d) is released with the aid of the venting line (28). The venting line (28) is guided separately from the control line (20) through the directional valve (26). In this way, a large air flow can be conducted through the venting line (28) without the static air pressure in the control space (50) of the directional valve (26) being reduced. The venting line is blocked by a stepped piston (44) of the directional valve when no air is to be released from the air springs.