A parking valve for manually actuating a spring-loaded parking brake, includes: a housing with a port that can be fluidically connected to a release chamber of a spring-loaded brake cylinder, a port that can be fluidically connected to a brake supply reservoir, and a ventilation port; a slide for manual actuation and which can be moved along a full section between two end positions inside the housing. The slide assumes positions along the full section, in which, as a result of at least one seal, there is no fluidic connection between the port to the release chamber and the ventilation port, and assumes other positions along the full section, in which, as a result of the at least one seal, there is no fluidic connection between the port of the release chamber and the port to the brake supply reservoir. A blocking device acts on the slide during movement at least along a partial section of the full section in at least one direction, with a continuously variable counterforce dependent on the position of the slide on the partial section.

A vehicle braking system comprising a spring brake actuator having a spring brake chamber, a spring brake control assembly and an immobiliser valve which is movable between brake release position in which the spring brake control assembly is operable to cause the flow of pressurised fluid into the spring brake chamber or to vent the spring brake chamber to a low pressure region, and an immobilise position in which the spring brake control assembly is operable to connect the spring brake chamber to a low pressure region but cannot be operated to cause the flow of pressurised fluid into the spring brake chamber.

A vehicle braking system comprising a spring brake actuator having a spring brake chamber, a spring brake control assembly and an immobiliser valve which is movable between brake release position in which the spring brake control assembly is operable to cause the flow of pressurised fluid into the spring brake chamber or to vent the spring brake chamber to a low pressure region, and an immobilise position in which the spring brake control assembly is operable to connect the spring brake chamber to a low pressure region but cannot be operated to cause the flow of pressurised fluid into the spring brake chamber.

A parking valve for manually actuating a spring-loaded parking brake, includes: a housing with a port that can be fluidically connected to a release chamber of a spring-loaded brake cylinder, a port that can be fluidically connected to a brake supply reservoir, and a ventilation port; a slide for manual actuation and which can be moved along a full section between two end positions inside the housing. The slide assumes positions along the full section, in which, as a result of at least one seal, there is no fluidic connection between the port to the release chamber and the ventilation port, and assumes other positions along the full section, in which, as a result of the at least one seal, there is no fluidic connection between the port of the release chamber and the port to the brake supply reservoir. A blocking device acts on the slide during movement at least along a partial section of the full section in at least one direction, with a continuously variable counterforce dependent on the position of the slide on the partial section.

A method of brake control of a vehicle combination (2) composed of a tractor vehicle (4) with an electronically controlled braking system (5) and a trailer vehicle (6, 8) with a pneumatically controlled pneumatic braking system (7, 9), involves introducing the brake control pressure (p.sub.BC) of the trailer vehicle (6, 8) into a tractor brake control line (19) extending to a tractor vehicle-side “brake” coupling head (26) via an electronically controlled trailer control valve (13) of the tractor vehicle (4). At the beginning of a braking operation, a pressure pulse (34) exceeding a target brake control pressure (p.sub.BC_soll) is introduced into the tractor brake control line (19). The volume of a trailer brake control line (28, 29, 32) coupled to the “brake” coupling head (26) is ascertained, and the absolute value (Δp.sub.PI) and/or the duration (Δt.sub.PI) of the pressure pulse (34) introduced are/is established depending on the ascertained volume.

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 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 of brake control of a vehicle combination (2) composed of a tractor vehicle (4) with an electronically controlled braking system (5) and a trailer vehicle (6, 8) with a pneumatically controlled pneumatic braking system (7, 9), involves introducing the brake control pressure (p.sub.BC) of the trailer vehicle (6, 8) into a tractor brake control line (19) extending to a tractor vehicle-side brake coupling head (26) via an electronically controlled trailer control valve (13) of the tractor vehicle (4). At the beginning of a braking operation, a pressure pulse (34) exceeding a target brake control pressure (p.sub.BC_soll) is introduced into the tractor brake control line (19). The volume of a trailer brake control line (28, 29, 32) coupled to the brake coupling head (26) is ascertained, and the absolute value (p.sub.PI) and/or the duration (t.sub.PI) of the pressure pulse (34) introduced are/is established depending on the ascertained volume.

A control apparatus is configured to control a brake of a unit hauled by a vehicle. The vehicle includes a plurality of brakes for braking the wheels of the vehicle, a trailer brake for braking the hauled unit, and a parking brake for keeping the vehicle braked while it is stationary. The control apparatus includes a line for sending a fluid to the trailer brake through a control valve in order to brake the hauled unit in certain working conditions, a further line for sending a further fluid to the trailer brake in order to activate the trailer brake in other working conditions, and a valve device for controlling flow of the further fluid in the further line, the valve device being responsive to a signal indicative of the status of the parking brake.