A fluid-operated braking system (1) for a tractor-trailer vehicle includes a trailer control valve (2), a parking brake module (3), and an electronic control unit (4) electrically connected to the trailer control valve (2) and to the parking brake module (3). A pressure fluid accumulator (13) of the braking system (1) is connected to a control pressure input (P43) of the trailer control valve (2). A redundancy circuit controls the control pressure input (P43), even during a malfunction of the control unit (4). The parking brake module (3) includes a control valve (14), a redundancy valve (15) and a changeover valve (16) controlled by an electronic switch unit (20) with a holding function. When the control unit (4) malfunctions, the last error-free switching position of the control valve (14) or the redundancy valve is maintained until a operationally safe resting state is reached or the ignition system is switched off.

In an embodiment, a vehicle makes a determination, during a second ignition-on cycle of the vehicle, that a trailer brake output circuit of the vehicle was operated during a first ignition-on cycle of the vehicle preceding the second ignition-on cycle. In response to making the determination, the vehicle presents a query, via a user interface of the vehicle, whether to operate the trailer brake output circuit according to a previously-used trailer profile according to which the trailer brake output circuit was operated during the first ignition-on cycle preceding the second ignition-on cycle. The vehicle receives a reply, associated with the query, via the user interface and, in response to receiving the reply, operates the trailer brake output circuit based on the reply.

In the event of a pneumatic trailer connection failure between a tractor and trailer of, e.g., a commercial vehicle, a pressure protection valve (PPV) is provided on the air line between a double check valve that supplies air from one or more service reservoirs and a trailer parking valve without a flow restrictor, which transmits the air to the trailer connection for supplying the trailer brakes. When output pressure on the PPV drops below a predetermined closing pressure threshold due to the connection failure, the PPV closes to protect the tractor brake air supply. Upon restoration of the trailer connection and upon input pressure at the PPV exceeding a predetermined opening pressure threshold, the PPV opens and the trailer brake system is charged more quickly than can be achieved using a conventional trailer parking valve with a flow restrictor.

A brake release system for a vehicle is described to transfer mechanical movement between two hydraulic actuators. The system includes a first hydraulic system on a removable portion of the vehicle and a second hydraulic system on a main chassis of the vehicle. The two hydraulic systems are mechanically engaged with each other where the removable portion of the vehicle attaches to the main chassis. In this way, a force applied to the removable portion of the vehicle when the vehicle's tow hook is engaged may be transferred to release the parking brake on the main chassis without a hydraulic connection between the removable portion and the main chassis. This may be useful when a removable battery frame with a tow hook makes up a separable rear portion of an electric vehicle, allowing the battery frame to be quickly and efficiently removed from the main chassis of the vehicle.

A valve arrangement (2) of a hydraulically braked tractor vehicle for controlling the brake pressure of a pneumatically braked trailer includes an electronically controlled trailer control valve (6) with an inlet valve (14), an outlet valve (16), a pneumatical relay valve (18), a breakaway valve (20) and a brake control pressure sensor (24). The valve arrangement also has a hydraulically controlled backup valve (8) with a hydraulically activated relay valve (46), a redundancy valve (48) and a hydraulic control pressure sensor (50). Output-side brake control lines (40, 76; 62, 78) are connected via a shuttle valve (10) to a brake coupling head (82). The valves (14, 16, 18, 20) and the pressure sensors (24, 50) of the trailer control valve (6), the valves (46, 48) of the backup valve (8,) and the shuttle valve (10) may be combined in one trailer control module (98) with a single housing (100).

A braking system of a work machine includes a pressurized fluid supply, a base valve fluidly coupled to the supply, a proportional control valve fluidly coupled to the supply, and a fluid output configured to be fluidly coupled to a braking system of a trailer. A first fluid path is selectively fluidly coupling the supply to the fluid output via the base valve, and a second fluid path is selectively fluidly coupling the supply to the fluid output via the proportional control valve. The base valve includes a predefined fixed gain and the proportional control valve includes an adjustable ratio.

A brake system includes a service brake and a parking brake that brake a vehicle including a lift axle capable of ascending and descending. The brake system further includes a brake blocker device and a controller that controls the brake blocker device. The brake blocker device blocks at least one of supply of compressed air to the service brake and supply of compressed air to the parking brake. The service brake and the parking brake act on the lift axle. The controller actuates the brake blocker device when the lift axle is at a lifted position.

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 tire pressure controlling device for a tire of a vehicle wheel filled with compressed air, includes a control valve unit for filling the tire with compressed air and/or venting compressed air therefrom. The control valve unit is supplied from a compressor for generating the tire filling pressure. The compressor for compressing air drawn in from the atmosphere is driven by the mechanical rotary movement of the vehicle wheel, as a transmission disposed therebetween transmits the rotary driving movement of the vehicle wheel to the drive shaft of the compressor unit.

A fluid-operated braking system (1) for a tractor-trailer vehicle includes a trailer control valve (2), a parking brake module (3), and an electronic control unit (4) electrically connected to the trailer control valve (2) and to the parking brake module (3). A pressure fluid accumulator (13) of the braking system (1) is connected to a control pressure input (P43) of the trailer control valve (2). A redundancy circuit controls the control pressure input (P43), even during a malfunction of the control unit (4). The parking brake module (3) includes a control valve (14), a redundancy valve (15) and a changeover valve (16) controlled by an electronic switch unit (20) with a holding function. When the control unit (4) malfunctions, the last error-free switching position of the control valve (14) or the redundancy valve is maintained until a operationally safe resting state is reached or the ignition system is switched off.