Abstract: A gas dryer having a housing, an outlet chamber, a pressure relief space, and a connection connecting the outlet chamber to the pressure relief space. An outlet valve is located within the connection connecting the outlet chamber to the pressure relief space. A piston which actuates opening and closing of the outlet is subjected to pressure contained in a control chamber. This pressure urges the outlet valve into an open position. The gas dryer also has an auxiliary valve system which is located between the control chamber and the pressure relief space. The auxiliary valve system controls the flow of the pressure medium between the control chamber and the relief space.

Abstract: A compressed gas system comprises a pressure generator and a consuming installation, a gas drier disposed between the pressure generator and the consuming installation, and an in-flow line connecting the pressure generator to the gas drier. Desirably, an out-flow line connects the gas drier to the consuming installation. A by-pass line also connects the pressure generator to the gas drier in parallel to the in-flow line. The by-pass line includes a pressure-controlled blocking device, such as a check valve, which allows the passage of gas from the pressure generator to the gas drier only when a predetermined opening pressure has been reached.

Abstract: A relay valve apparatus having two relay valves are located in a single housing with their longitudinal axes parallel to one another. The two relay valves each include a double seat valve and a relay piston. The two relay valves are located one behind the other in the direction along their longitudinal axes so that the two double seat valves are located between the relay pistons. An outlet chamber of the first double seat valve and an outlet chamber of a second double seat valve empty into a common fluid pressure outlet leading to the atmosphere.

Abstract: The present invention provides a pressure regulating valve which substantially avoids shutoff noises. The pressure regulating valve is designed such that the opening process of the shutoff valve proceeds in two steps. The two-step switching process is made possible by the provision of a seal ring which slides on an activating piston which activates the shutoff valve. This seal ring acts upon a housing mounted detent and an activating piston mounted additional detent, thus creating an automatically acting additional surface area for the activating piston. This design also makes it possible to increase the safety function of the pressure regulating valve, by increasing the pressure medium activated surface area of the valve body for the shutoff valve without incurring higher work forces at the activating piston.

Abstract: A relay valve device which is actuated by the presence of a control signal pressure to a higher pressure supply into a consumer circuit than when the control signal pressure is not present. The relay valve device includes a first control surface and a second control surface, and includes a shut-off device disposed in the feed line of the control pressure to the second control surface. The shut-off device is opened when the control signal pressure is present and is closed when the control signal pressure is not present, and also causes the second control surface to be connected with atmosphere.

Abstract: This invention relates to a brake pressure control valve and, more particularly, to a tractor-trailer control valve which includes a differential pressure surface relay piston that on one hand is acted upon by the control pressure from a control chamber and on the other hand by modulated pressure from a working chamber. The brake pressure control valve includes a first combination inlet and outlet valve which works together with the relay piston whereby the working chamber can be pressurized and vented via the first inlet and outlet valves. An auxiliary control chamber which is defined by the differential surfaces of the relay piston is connectable either to the working chamber or to the control chamber via second inlet and outlet valves. The pressure control surface of the relay piston is located opposite the working surface that is acted upon by control pressure in the control chamber. The pressure control surface can be enlarged by the pressure surface of the auxiliary control chamber.

Abstract: The invention relates to a pneumatic relay valve for regulating output pressure in proportion to a control pressure.The relay valve includes a first piston member which is acted on by the control pressure and a second piston member which is acted on by the input pressure.A compression spring is located between the two relay piston members.The strength of the compression spring determines the height of a predetermined minimum controlled pressure even if the input pressure is subsequently lost or drops to a low value.In addition, the output pressure of a receiver can be maintained at a specific adjustable level which may be below the maximum pressure value of the input pressure due to the compression spring located between the two relay piston members.

Abstract: This invention relates to a control system for a pneumatically cushioned vehicle having at least a first and a second pneumatically cushioned axle. The pressure in the air spring bellows of the second axle is controlled in accordance with the air spring bellows of the first axle. The air spring bellows of the second axle are connected to a source of supply pressure by a pneumatic relay valve. The relay valve includes a control inlet which is connected with the air spring bellows of the first axle. The relay valve is designed in such a way, that if no pressure or a relatively low control pressure is present at the control inlet, the pressure at an outlet port of the relay valve leading to the air spring bellows of the second axle will be maintained at a minimum value. The relay valve includes a first control chamber and a second control chamber which are separated by a relay piston.

Abstract: In a variable load valve device of the type employing a walking beam type lever arrangement via which the control and compensating pistons are interconnected to obtain proportional control of the brake pressure, there is provided an externally accessible screw adjustment for varying the tension of a bias spring acting on one of the levers, whereby the proportional brake control is withheld until a predetermined level of brake pressure is achieved corresponding to the spring bias.