The invention relates to a parking and maneuvering valve for trailers having a spring-loaded parking brake. The aim of the invention is to produce a braking system without a trailer braking valve. The invention provides a release unit, a parking unit and an emergency brake unit functionally assigned to the two units. The release unit, parking unit and emergency brake unit are interactively connected so that the parking unit convoys the pressure exerted by the reservoir of the trailer by the emergency brake unit or conveys the pressure exerted by the coupling head "reservoir" by the emergency brake unit to the spring-loaded parking brake system.

An electronic braking system for wheeled vehicles comprising an electronic controller which produces, in response to driver braking demands, electronic signals for controlling the braking pressures applied to the vehicle wheels from a source of braking pressure. The system includes a second, back-up braking pressure source which can be selected when required, and means for switching over from the first-mentioned normal source of braking pressure to the back-up pressure source at selected occasions when the vehicle is being braked and has come to rest, provided that the prevailing driver's braking demand is above a predetermined minimum threshold. A test is then performed on the braking pressure signals generated by the system while it is energized by the back-up source and a warning signal is generated if the back-up source is found to be faulty.

The electrohydraulic or electropneumatic braking-control device for axles of trailers having mechanical brakes includes a hydraulic or pneumatic circuit mounted on the trailer, made up principally of a pressure accumulator, the internal pressure of which is automatically adjusted above a minimum value, as well as of a control gate, the opening of which is proportional to a control current function of the pressure exerted on the brake pedal of the tractor vehicle and of an adjustment carried out as a function of the load of the trailer. In case of attachment parting or of unhitching of the trailer, the disconnection of the connection plug actuates a safety valve that automatically controls the energetic braking of the trailer. The safety valve includes a manual control. It is possible to unbrake, then to rebrake the trailer in order to maneuver it. The trailer braking device may be mounted from the outset or subsequently, requiring only few transformations of the tractor vehicle.

An electronic air charge controller for a tractor trailer vehicle air brake system includes a micro controller, a first pressure sensor interface coupled to the micro controller, a second pressure sensor interface coupled to the micro controller, and a vehicle control protocol interface coupled to the micro controller. The micro controller, in response to a signal received from the first pressure sensor interface indicative of an air supply recharge condition, a signal received from the second pressure sensor indicative of parking brake engagement condition, and a signal from the vehicle control protocol interface indicative of an engine start condition, supplies a maximum engine speed control signal to the vehicle control protocol interface. The time required to charge the air supply system to the required normal operating level is thereby minimized. In addition, a transmission sensor interface is preferably coupled to the micro controller. The micro controller does not generate the maximum engine speed control signal unless a signal supplied by the transmission sensor interface indicates that an automatic transmission is in park or a manual transmission is in neutral. Still further, to improve operating efficiency, a vehicle load condition signal is supplied by the vehicle control protocol interface to the micro controller. In response, the micro controller supplies a pause air compressor charging cycle signal or a pause air dryer recycle signal to the vehicle control protocol interface, if either the air compressor or air dryer is operating when a high load condition is encountered.

An electrical braking system for a motor vehicle has a controller which detects the actuation of a service-brake operator element, determines therefrom at least one driver's braking input for the brake control, and supplies this set point value to control units for controlling the wheel brakes. This controller also detects the actuation of a parking-brake operator element, determines therefrom a parking-brake input of the driver, and links this parking-brake input with the braking input for the service brake to form the total braking input. An electrical braking system for a motor vehicle includes at least one control unit which is allocated to at least one wheel brake. The controller controls an actuator for actuating the wheel brake on the basis of a setpoint value. The actuator has an electric motor and a locking device, in particular, a disengaging device. To actuate the wheel brake via the electric motor, the locking device is released. After the actuation has terminated, the locking device is again closed. A further controller for a different wheel brake is supplied with energy from a different energy-supply system. It activates an additional resetting possibility in the actuator in the event of a fault.