Abstract: An air drier tower comprises a base part (2), a reservoir (1) attached thereto, and in the reservoir a cartridge (7) containing desiccant (8). The cartridge is composed of two halves (9,10) having circular walls extending into each other to form a winding air path through the desiccant. A spring (11) is arranged between the reservoir and the cartridge in order to exert a bias on one cartridge half and accordingly on the desiccant.

Abstract: An inlet valve for a two-tower air drier for directing an air flow from a central inlet to either tower through a respective one of a pair of opposed outlets. A valve body is axially movable between two valve seats and is provided with two annular flanges at such an axial distance from each other that at no position of the valve body will a flange cover any part of the central inlet. A restricted flow area past the flanges is accomplished as a flange moves towards its respective valve seat. The valve body is biased towards a neutral position by a helical compression spring, which is attached to the housing of the valve with its two ends and passes through an aperture in a stem of the valve body between the two flanges.

Abstract: The compressed air flow in an air drier is directed to either one of its two drying towers by a switch-over valve whose switch-over function is performed with the air drier unloaded by an unloader valve arranged between the air drier and a compressor. The unloader valve is caused to perform its unloading function not only at a predetermined pressure in an air tank to which the air is fed but also--by an electronic control device--after a predetermined time during periods of prolonged continuous air loading from the compressor through the air drier even if the predetermined pressure is not reached.

Abstract: A switch-over valve for directing a compressed air flow to either one of two drying towers of an air drier, the other one being vented to the atmosphere through the valve. A positively operated valve body is movable between two valve seats in a central chamber. A valve sleeve arranged at either side of the valve body is axially movable in a dividing wall between the central chamber and a respective outer chamber connected to the drying tower, is spring biased in a direction towards the valve body to a position where a radial valve sleeve flange in the outer chamber is in sealing contract with the wall, and is biased in the opposite direction by the valve body for lifting the flange from the wall and venting out the air from the outer chamber to the atmosphere through a channel in the wall.

Abstract: A switch-over valve for directing a compressed air flow to either one of two drying towers of an air drier, the other one being vented to the atmosphere. The valve is arranged in a partition wall between the two towers, a conduit to the valve being provided in the partition wall. A valve body is axially movable in a cavity in the wall between two positions sealing off either one of the outlets from the cavity and keeping the other one open. A control piston with a greater length than the valve body is axially movable in a bore in the valve body and is biased towards a neutral position by spring means.