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 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).

The disclosure is directed to a fail-safety valve unit for a parking brake function of an electronically controllable pneumatic braking system for a utility vehicle. The fail-safety valve unit has a monostable release valve and a ventilating valve. The release valve, when energized, provides a release pressure at a first release valve port for the parking brake function and, when de-energized, connects the first release valve port to the ventilating valve. The ventilating valve has a nonlinear ventilating characteristic which permits ventilating of the release valve port from the release pressure to a partial brake pressure with a first gradient, and ventilating of the release valve port from the partial brake pressure to a full brake pressure with a second gradient, wherein the first gradient is greater than the second gradient. A parking brake module and a vehicle are part of the disclosure.

A parking brake valve assembly for an electronically controllable pneumatic braking system of a vehicle is disclosed. The parking brake valve assembly includes: a first compressed air path which receives a supply pressure and has a first monostable valve unit for providing a first parking brake pressure, a second compressed air path which receives supply pressure and has a second monostable valve unit for providing a second parking brake pressure, and a first shuttle valve having a first shuttle valve port with the first compressed air path and receiving the first parking brake pressure, a second shuttle valve port with the second compressed air path and receiving the second parking brake pressure, and a third shuttle valve port connectable to a spring brake cylinder. The first shuttle valve outputs the higher of the first parking brake pressure and of the second parking brake pressure to the third shuttle valve port.

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).

A braking arrangement for a vehicle includes a source of pressurized air, a first wheel with a first pneumatic brake arrangement including a first brake, the first brake being arranged to be engaged when connected to the source of pressurized air and disengaged when disconnected from the source of pressurized air, a second wheel with a second pneumatic brake arrangement including a second brake, the second brake being arranged to be engaged when connected to the source of pressurized air and disengaged when disconnected from the source of pressurized air, and a proportional valve between the source of pressurized air and the first brake, opening of the proportional valve being proportional to pressure in a line between the source of pressurized air and the proportional valve. The first pneumatic brake arrangement and the second pneumatic brake arrangement function differently.

A parking brake apparatus is provided for a power unit having air brake parking components and to which a towed unit having air brake parking components can be connected. The parking brake apparatus comprises a controller arranged to monitor a pressure signal indicative of a delivery air pressure applied to the air brake parking components of the towed unit when the towed unit is connected to the power unit. The controller is also arranged to provide a status signal indicative of whether or not a towed unit is connected to the power unit based upon the pressure signal. The controller further enables the status signal to be processed to control application or release of any combination of air brake parking components of the power unit and the towed unit to park or unpark the power unit as well as the towed unit, if connected to the power unit.

A valve arrangement (14.2) of a tractor vehicle (2) for controlling a pneumatic brake system of a trailer vehicle (4) includes a trailer control valve (16) with a reservoir pressure input (p11) for the introduction of reservoir compressed air and a reservoir pressure output (p21) for the controlled discharge of reservoir compressed air. The reservoir pressure output is pneumatically connected to a “reservoir” coupling head (6) of the tractor vehicle. A shut-off and ventilation valve (98) is arranged in a reservoir pressure line (48) upstream of the “reservoir” coupling head. Before connecting an associated coupling head of the trailer vehicle (4) to the “reservoir” coupling head of the tractor vehicle, the feed of reservoir compressed air to the “reservoir” coupling head can be shut off to ventilate the “reservoir” coupling head. After reconnecting the associated coupling head, the “reservoir” coupling head can be charged again.

An electropneumatic parking brake control device controls a parking brake including at least one spring brake actuator. The control device includes a relay valve with a control chamber and a vent. The control chamber can be connected to the vent via at least one second throttle element and/or at least one third throttle element depending on the position of the relay piston.