A pneumatic braking device for a utility vehicle includes at least one pneumatically controllable spring accumulator for a parking brake of the utility vehicle and an electronic parking brake device. The electronic parking brake device has at least one electronic control unit, at least one bistable valve unit, at least one first valve unit by which a parking brake of a trailer of the utility vehicle can be deactivated when activating the parking brake of the utility vehicle, at least one second valve device which can be connected in such a way that when there is a decrease in the system pressure for supplying the parking brake of the trailer, the parking brake of the trailer can be activated, and a traction vehicle protection valve.

A method includes steps for controlling a pneumatic braking system of a trailer vehicle which is connected to a tow vehicle equipped with a hydraulic or pneumatic braking system. At the start of an actuation of the foot brake valve, an electrical switch is closed or opened, and a switching signal is transmitted to an electronic control unit as a braking start signal for an incipient braking process. A brake value sensor detects a brake value representative of the drivers current deceleration request and transmits the brake value to the electronic control unit as a brake value signal. The brake value sensor is used for determining the incipient braking process, and a backup valve is only deactivated by switching a redundancy valve from an open position to a blocking position if the brake value signal detected by the brake value sensor has reached or exceeded a predefined minimum signal value.

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 pneumatic braking device for a utility vehicle includes at least one pneumatically controllable spring accumulator for a parking brake of the utility vehicle and an electronic parking brake device. The electronic parking brake device has at least one electronic control unit, at least one bistable valve unit, at least one first valve unit by which a parking brake of a trailer of the utility vehicle can be deactivated when activating the parking brake of the utility vehicle, at least one second valve device which can be connected in such a way that when there is a decrease in the system pressure for supplying the parking brake of the trailer, the parking brake of the trailer can be activated, and a traction vehicle protection valve.

A parking brake device for motor vehicles has at least one first parking brake unit and one second parking brake unit, wherein the first parking brake unit has at least one first compressed air connector, a first inlet-ventilation solenoid valve unit, a first relay valve, a spring brake valve and at least one first compressed air outlet. The first compressed air connector is connected to the first inlet-ventilation solenoid valve unit and the first relay valve. A first control line is provided in the first parking brake unit in such a way that the first relay valve is connected to the first inlet-ventilation solenoid valve unit, wherein the first control line has a first branch upstream of the first relay valve, and wherein a first outlet line is provided in the first parking brake unit, which first outlet line is connected to the at least one first compressed air outlet and has a first outlet branch. A spring brake line is provided in the first parking brake unit, which spring brake line is connected via a first branch to the first control line and via the first outlet branch to the outlet line. The first parking brake unit has a spring brake valve which is arranged in the spring brake line and is connected to the first relay valve, and a first throttle unit which is arranged in the spring brake line between the first outlet branch of the first outlet line and the first branch of the first control line.

A method for electronically controlling a brake unit having two brake systems in an automatically controllable vehicle combination includes inputting a request signal for automatic electronic activation of service brakes in a tractor vehicle brake system of a tractor vehicle and/or a trailer brake system of a trailer of the vehicle combination, wherein an automatically requested vehicle setpoint acceleration and/or an automatically requested vehicle setpoint velocity to be implemented by the respective service brakes are transmitted via the request signal. The method further includes monitoring and checking plausibility of the request signal to establish whether the automatically requested vehicle setpoint acceleration and/or the automatically requested vehicle setpoint velocity are or can be implemented completely or faultlessly by the respective service brakes. The method additionally includes outputting a trailer redundancy control signal at the trailer brake system under certain conditions.

A trailer control module (94) of a pressure-medium operated braking system of a tow vehicle has a valve assembly for controlling a pneumatic braking system of a trailer vehicle The valve assembly includes the following: an electronically controlled trailer control valve (6) which contains a pneumatically controlled relay valve (18) with an inverted control input (34); a pressure-medium controlled backup valve (8) which contains a pressure-medium controlled relay valve (54); and at least one electronically controlled parking brake valve (68, 70), via which the relay valve (18) of the trailer control valve (6) can be actuated pneumatically at its inverted control input (34). In addition, a coupling device (98) is present, by which the parking brakes of the tow vehicle can also be operated via the parking brake valve (68, 70).

A trailer brake control module (300a; 300b; 300c) for a towing vehicle (502) facilitating braking of a towed vehicle or trailer (504) includes a pressure supply port (P11), a trailer control pressure port (P22), a primary control port (P42) for receiving either directly and/or indirectly a control brake pressure for operating the trailer brake control module (300a; 300b; 300c). The primary control port (P42) receives the control brake pressure from a pneumatically operated pressure medium, a pneumatic control pressure line (308.1) provides alternative control brake pressure for operating the trailer brake control module (300a; 300b; 300c), wherein the pneumatic control pressure line (308.1) receives the alternative control brake pressure from an electronically operated pressure medium, and a relay valve (310) is activated using either the control brake pressure received at the primary control port (P42), or the alternative control brake pressure from the pneumatic control pressure line (308.1).

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.

An extendable/retractable step assembly mounted at the rear assembly of a flatbed trailer to permit access to and from the ground to the flatbed trailer. The extendable/retractable stair assembly includes a pair of steps that are staggered and can be extended out of the rear assembly during use and then retracted therein when not in use. The steps can be manually extended/retracted or they can be automatically controlled. A safety interlock is also disclosed to automatically retract the steps when the trailer emergency brakes are released.