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).

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.

An electropneumatic parking brake module (1) includes a supply connection (2), a spring-type actuator connection (4), an inlet-outlet valve unit (10) having a first switching position and a second switching position, and an electropneumatic pilot control unit (12) for outputting at least a first control pressure (p1) at the inlet-outlet valve unit (10). In the first switching position of the inlet-outlet valve unit (10), a spring brake pressure (pF) can be fed through directly from the supply connection (2) to the spring-type actuator connection (4) by virtue of the fact that the spring-type actuator connection (4) is connected to the supply connection (2), and, in the second switching position of the inlet-outlet valve unit (10), when the first control pressure (p1) is below a first threshold value, the spring-type actuator connection (4) is connected to a ventilating connection (14.3) of the inlet-outlet valve unit (10).

An electronically controllable pneumatic brake system includes a service brake control module for controlling a first and a second service brake circuit, and a trailer control module with a trailer brake pressure connection point for connection to a trailer brake pressure coupling head. The trailer control module outputs a trailer brake pressure via the trailer brake pressure connection point. Upon a malfunction of the first and/or second service brake circuit, the first service brake pressure is controlled depending on the trailer brake pressure; and the second service brake pressure is controlled depending on the trailer brake pressure specified by the trailer control module; and/or the parking brake pressure is controlled directly or depending on the trailer brake pressure specified by the trailer control module. Upon a malfunction of the trailer control module, the trailer brake pressure is controlled depending on the first service brake pressure.

An electropneumatic control module for an electronically controllable pneumatic brake system for a vehicle combination with a tractor vehicle and a trailer vehicle includes a pneumatic reservoir input, which is connectable to a compressed-air reservoir, a trailer control unit, which has a trailer control valve unit with one or more electropneumatic valves, a trailer brake pressure port and a trailer supply pressure port, an immobilizing brake unit, which has a spring-type actuator port for a spring-type actuator for a tractor vehicle and an immobilizing brake valve unit with one or more electropneumatic valves, and an electronic control unit for controlling the trailer control valve unit and the immobilizing brake valve unit. The trailer control unit has a first relay valve, which has a relay valve working input connected to the reservoir input, a relay valve output connected to the trailer brake pressure port, and a relay valve ventilation output.

A method for testing a pressure-medium-operated electronic brake system of a vehicle having a valve and sensor device including a control pressure inlet, a control pressure outlet, a plurality of valves selected from electrically activated inlet valves, outlet valves, redundancy valves, and pressure valves, an actual pressure sensor for measuring an actual control pressure, a setpoint pressure sensor for measuring a setpoint control pressure, and an electronic control unit, which has a signal-conducting connection to the electrically activated valves and pressure sensors, for receiving pressure signals and actuating the electrically activated valves, includes testing the setpoint pressure sensor while the control unit is in a passive operating mode, passing the setpoint control pressure directly through to the control pressure outlet, measuring the actual pressure at the control pressure outlet using a sensor, and transmitting the measured value to the control unit for plausibility checking against the setpoint pressure measurement.

An apparatus for controlling a trailer parking brake status indicator in a tractor is provided that allow an operator to deactivate the indicator when the tractor is operating without a trailer using a pre-existing operator interface. The apparatus includes means for determining whether a trailer is coupled to the tractor and a controller configured to execute, when a determination whether the trailer is coupled to the tractor cannot be made, a process for controlling activation and deactivation of the indicator. The process includes determining whether a speed of the tractor meets a predetermined condition relative to a predetermined speed. The process further includes monitoring, after determining that the speed of the tractor meets the predetermined condition relative to the predetermined speed, for an activation command to activate a parking brake on the trailer. The process further includes deactivating the trailer parking brake status indicator responsive to the activation command.

A trailer control valve comprises a valve electronic control port adapted to receive an electronic control signal; a valve pneumatic supply port unrestrictedly fluidly communicating with a first supply of a pneumatic fluid; a valve pneumatic control port normally proportionally fluidly communicating with a second supply of the pneumatic fluid based on a pressure representing a driver brake demand, the first supply of the pneumatic fluid being in an independent pneumatic circuit from the second supply of the pneumatic fluid; and a valve delivery port selectively fluidly communicating with at least one of the valve pneumatic supply port and the valve pneumatic control port based on the electronic control signal, the pressure representing the driver brake demand and a pressure of the first supply of the pneumatic fluid. A first pneumatic check valve includes a first check valve supply port fluidly communicating with the first supply of the pneumatic fluid; and a first check valve delivery port fluidly communicating with the relay valve pneumatic supply port. The first pneumatic check valve controls the fluid communication of the first supply of the pneumatic fluid with the relay valve pneumatic supply port based on the pressure of the first supply of the pneumatic fluid at the valve pneumatic supply port.

An electropneumatic trailer control module (1) for an electronically controllable pneumatic brake system (520) for a vehicle combination (500) with a tractor vehicle (502) and a trailer vehicle (504), has an electronic control unit (ECU), a pneumatic reservoir input (11), a trailer control valve unit (65) with electropneumatic valves (RV, IV, OV), a trailer brake pressure port (22), and a trailer supply pressure port (21). The electronic control unit (ECU) has a parking brake signal input (200) for receiving an electronic brake representation signal (SB1, SB2, SB3) for an immobilizing brake (6, 532a, 532b) of the tractor vehicle (502) and is configured to, on the basis of the brake representation signal (SB1, SB2, SB3), switch at least one of the one or more electropneumatic valves (RV, IV, OV) of the trailer control valve unit (65) in order to output a brake pressure.

An electronic brake system for a trailer with a pneumatic brake installation is disclosed. The electronic brake system comprises a brake controller (18) in the trailer (11) connected to a first communication device (20) that is part of a first communication channel (23) for wirelessly receiving brake signals of a towing vehicle (10). The electronic brake system also comprises a second communication channel for receiving brake signals of the towing vehicle. The brake controller (18) converts the brake signals of the first communication channel (23) into brake commands for the pneumatic brake installation only if brake signals arrive via the second communication channel (24) at the same time or within a defined time window. The time window begins as soon as a brake signal arrives on one of the first and second communication channels (23, 24).