A tractor protection valve having a parking brake supply port, a parking brake delivery port, an exhaust port, and a quick release valve positioned between the parking brake supply port and the parking brake delivery port. The quick release valve is movable between a supply position allowing fluid to flow from the parking brake supply port to the parking brake delivery port and an exhaust position allowing fluid to flow from the parking brake delivery port to the exhaust port. The quick release valve may include a diaphragm that is movable between the supply and exhaust positions. The quick release valve may include a valve body that is positioned in a housing of the tractor protection valve.

A method is for operating a vehicle combination having a tractor and at least one trailer. A brake control unit of a tractor brake system monitors the braking behavior of the tractor or the vehicle combination, and if necessary the brake pressure at each of the wheel brakes of the tractor, and initiates the deceleration of the trailer. To improve the driving safety of the vehicle in the event of limitation of the functionality of components of the vehicle combination, at least one vehicle component of the tractor and/or of the trailer, the vehicle component being relevant for driving safety, is monitored with regard to functionality, and in the event of detection of a limitation of the functionality of a component, the brake control unit of the tractor brake system decelerates the vehicle combination using a trailer brake system of the trailer.

A method is disclosed for controlling the brakes of a vehicle combination that includes a tractor vehicle and at least one trailer vehicle. A brake control valve in the tractor vehicle has magnetic switching valves that controlled by an electronic control unit, including an inlet valve and an outlet valve. To determine a current trailer status, it is determined whether the tractor vehicle is connected to a trailer vehicle and/or the line volume of the brake control line. A target pressure to be produced in the brake control line is specified and is produced by pulse-like opening of the inlet valve and/or the outlet valve. The brake control pressure in the brake control line is measured during the pressure build-up of pressure and a characteristic value for the trailer status and/or for the line volume of the brake control line is determined.

A vehicle includes a chassis, a tractive element coupled to the chassis, and a parking brake system. The chassis includes at least one of a transmission or a structural frame. The parking brake system includes a parking brake configured to brake the tractive element when engaged. The parking brake is configured to be disengaged to permit rotation of the tractive element in response to the parking brake receiving a fluid. The parking brake system includes a fluid supply configured to supply the fluid to the parking brake to disengage the parking brake. The fluid supply is configured to stop supplying the fluid in response to a component of the vehicle ceasing operation. The parking brake system includes a pump coupled to the chassis and configured to supply the fluid to the parking brake at least when the component of the vehicle is not operating.

A braking controller causes a tractor protection control module in a tractor to prevent air flow from an air reservoir to a gladhand when the braking controller determines that the trailer is not pneumatically coupled with the gladhand. This prevents air from being vented out the gladhand when the tractor's service brakes are applied. The braking controller can detect pneumatic discontinuity, for example, by receiving a notification from a parking brake controller or from a pressure sensor in the tractor protection control module.

A brake module for a hydraulically braked tractor coupled to a pneumatically braked trailer has a trailer control valve connected via hydraulic control inlet to a hydraulic pressure line leaving a master brake cylinder, and via pneumatic inlet to a compressed air reservoir. Hydraulic control pressure determines pneumatic output pressure level at a trailer control valve pneumatic outlet. The brake module has a break-off prevention module which, if the control line leaks or separates from the trailer control valve relative to the trailer brake system, closes a supply pressure coupling head supply line and causes trailer brake system venting. The break-off prevention module has a pneumatic supply pressure inlet and a pneumatic tear-off control pressure inlet connected to the air reservoir independently of trailer control valve pressure inlets. Supply pressure inlet supply pressure passes through the break-off prevention module and feeds to a trailer control valve pneumatic supply pressure inlet

A parking brake system for electrically controlling a parking brake of a vehicle is provided. The parking brake system includes a parking brake provided for each wheel, an air dryer controller, and an actuator. The air dryer controller is provided to an air dryer to electrically control the parking brake. The air dryer dries compressed air for use in the parking brake. The actuator is provided for each axle of the wheel to actuate the parking brake with the compressed air in accordance with an electric signal from the air dryer controller.

An air actuated brake system for use on a heavy-duty vehicle having a frame. Each of a first pair of air actuated brake assemblies is mounted to a first axle supported by the frame. Each of a second pair of air actuated brake assemblies is mounted to a second axle supported by the frame. A source of pressurized air is provided. Valve structure is in fluid communication with the source of pressurized air. The valve structure is located substantially central relative to each of the air actuated brake assemblies. Conduits of substantially equal length and/or volume fluidly connect the valve structure with the first pair of air actuated brake assemblies and with the second pair of air actuated brake assemblies to actuate the air actuated brake assemblies at substantially the same time.

Systems and methods are provided for controlling operation of a trailer brake system associated with an agricultural vehicle-trailer combination, including: determining a trailer brake temperature; comparing the determined trailer brake temperature with one or more temperature thresholds to determine a temperature level condition for the trailer brake; and controlling the trailer brake system in dependence on the determined temperature level condition.

A tractor protection valve having a parking brake supply port, a parking brake delivery port, an exhaust port, and a quick release valve positioned between the parking brake supply port and the parking brake delivery port. The quick release valve is movable between a supply position allowing fluid to flow from the parking brake supply port to the parking brake delivery port and an exhaust position allowing fluid to flow from the parking brake delivery port to the exhaust port. The quick release valve may include a diaphragm that is movable between the supply and exhaust positions. The quick release valve may include a valve body that is positioned in a housing of the tractor protection valve.