A pressure-limiting valve has a valve housing, a piston, a pressure-limiting adjustment spring, at least one inlet and at least one outlet. The piston can assume an open position in which the inlet and the outlet are connected to each other and a closed position which separates the inlet and outlet. A first piston ring has a sealing surface and has a small pneumatic active surface relative to a second piston ring. Between the first and second piston rings the piston has a substantially truncated cone-like portion which tapers toward the first piston ring. In the closed position, the sealing surface of the first piston ring is sealingly drawn against a housing collar by a pneumatic force acting counter to the force of the pressure-limiting adjustment spring. A pneumatic passage for creating a safety valve function closable by a spring-loaded safety valve body is provided in the piston.

A pressure-limiting valve has a valve housing, a piston, a pressure-limiting adjustment spring, at least one inlet and at least one outlet. The piston can assume an open position in which the inlet and the outlet are connected to each other and a closed position which separates the inlet and outlet. A first piston ring has a sealing surface and has a small pneumatic active surface relative to a second piston ring. Between the first and second piston rings the piston has a substantially truncated cone-like portion which tapers toward the first piston ring. In the closed position, the sealing surface of the first piston ring is sealingly drawn against a housing collar by a pneumatic force acting counter to the force of the pressure-limiting adjustment spring. A pneumatic passage for creating a safety valve function closable by a spring-loaded safety valve body is provided in the piston.

A pressure-limiting valve includes a housing having a piston, a pressure-limiting adjusting spring, at least one inlet and at least one outlet. The piston can assume an open position in which the inlet and the outlet are connected to each other, and at least one closed position in which the inlet and the outlet are separated from each other. The piston has a first piston ring with a sealing surface and a second piston ring. In the closed position, the sealing surface is drawn against a housing projection in a sealing manner by a pneumatic force which acts on the second piston ring and is directed against the force of the pressure-limiting adjusting spring. A pneumatic passage in the piston which implements a safety valve function can be sealed by a spring-loaded safety valve body arranged on a side of the second piston ring that is opposite the outlet.

A pressure-limiting valve includes a housing having a piston, a pressure-limiting adjusting spring, at least one inlet and at least one outlet. The piston can assume an open position in which the inlet and the outlet are connected to each other, and at least one closed position in which the inlet and the outlet are separated from each other. The piston has a first piston ring with a sealing surface and a second piston ring. In the closed position, the sealing surface is drawn against a housing projection in a sealing manner by a pneumatic force which acts on the second piston ring and is directed against the force of the pressure-limiting adjusting spring. A pneumatic passage in the piston which implements a safety valve function can be sealed by a spring-loaded safety valve body arranged on a side of the second piston ring that is opposite the outlet.

The disclosure provides an anti-lock brake device including an oil pressure tank, a first piston and a second piston. The oil pressure tank has an internal space, an oil inlet and an oil outlet that are connected to one another. The first piston is slidably located in the internal space, and has a first oil channel penetrating a contact portion of the first piston and connected to the oil inlet. The second piston is slidably located in the internal space and includes a push portion, and an outer diameter of the push portion is smaller than that of the contact portion. When the second piston is in a closed position, a chamber having a first unoccupied volume is formed in the internal space. When the second piston is moved from the closed position to a depressurized position, the first volume of the chamber is increased to a second volume.

The disclosure provides an anti-lock brake device including an oil pressure tank, a first piston and a second piston. The oil pressure tank has an internal space, an oil inlet and an oil outlet that are connected to one another. The first piston is slidably located in the internal space, and has a first oil channel penetrating a contact portion of the first piston and connected to the oil inlet. The second piston is slidably located in the internal space and includes a push portion, and an outer diameter of the push portion is smaller than that of the contact portion. When the second piston is in a closed position, a chamber having a first unoccupied volume is formed in the internal space. When the second piston is moved from the closed position to a depressurized position, the first volume of the chamber is increased to a second volume.

Hydraulic valves for dampening pressure spikes and associated methods are disclosed herein. In one embodiment, a hydraulic valve for dampening pressure spikes includes: a spool configured to move axially inside the hydraulic valve; and a sleeve configured to at least partially house the spool. A location of the spool with respect to the sleeve may determine a flow of a working fluid through the hydraulic valve. A viscous damper is at least partially housed inside an opening in the spool, and a viscous friction between the viscous damper and the opening in the spool slows a motion of the spool.

Hydraulic valves for dampening pressure spikes and associated methods are disclosed herein. In one embodiment, a hydraulic valve for dampening pressure spikes includes: a spool configured to move axially inside the hydraulic valve; and a sleeve configured to at least partially house the spool. A location of the spool with respect to the sleeve may determine a flow of a working fluid through the hydraulic valve. A viscous damper is at least partially housed inside an opening in the spool, and a viscous friction between the viscous damper and the opening in the spool slows a motion of the spool.

A brake retarder valve for a tractor-trailer combination includes a valve housing and a valve assembly. The valve assembly includes a poppet valve biased by a spring and a gravity spool. The valve assembly is selectively operable between the operative closed configuration and an open configuration in response to a resultant of the fluid pressure between a trailer axle brake and a tractor axle brake. The tractor axle brake is actuated with a time delay from actuation of the trailer axle brake. This delay is actuation of the tractor axle brake prevents jack knifing of the trailer onto the tractor in a tractor-trailer combination, thereby ensuring safety during operation of a tractor-trailer combination.

A brake retarder valve for a tractor-trailer combination includes a valve housing and a valve assembly. The valve assembly includes a poppet valve biased by a spring and a gravity spool. The valve assembly is selectively operable between the operative closed configuration and an open configuration in response to a resultant of the fluid pressure between a trailer axle brake and a tractor axle brake. The tractor axle brake is actuated with a time delay from actuation of the trailer axle brake. This delay is actuation of the tractor axle brake prevents jack knifing of the trailer onto the tractor in a tractor-trailer combination, thereby ensuring safety during operation of a tractor-trailer combination.