Abstract: Apparatus for controlling supply of air to front brakes in an air brake system of a truck when a manually operable valve (16) is operated to inhibit flow of air to the front brakes comprises a by-pass loop (17, 17') including an electrically operable valve (19). The valve is operated when a switch (28) is closed on moving a gear selection lever (29) to a position to select reverse gear.

Abstract: Apparatus for controlling the speed of an engine of a vehicle includes a processor (26) for comparing actual speed of the engine with a reference speed and for generating output signals if the actual speed is in excess of the reference speed, the output signals controlling valves (13, 14 and 15) of an air supply system (12) to a retarder of the vehicle and being arranged to operate sequentially to control progressively magnitude of power applied to the retarder if control of the vehicle is not effected to reduce speed of the engine during sequential periods of predetermined duration.

Abstract: Apparatus for limiting the allowed movement of a vehicle, such as a dump truck, when one of its components (e.g. the tippable truck bed or skip) is positioned out of its rest position. An interlock is provided which permits the vehicle to be driven for only a short distance with this component out of its normal rest position before the brakes of the vehicle are automatically applied. Thus, in the case of a dump truck, the vehicle can be driven forwardly with the bed raised only for a relatively short distance (e.g. so as to be moved clear of the load deposited by the tipped truck bed).

Abstract: Apparatus for controlling speed of a vehicle having a retarder includes a receiver (1) for receiving signals from a transmitter (2) indicative of a reference speed and a processor (26) for comparing actual speed of the vehicle with the reference speed and for generating output signals if the actual speed is in excess of the reference speed, the output signals controlling valves (13, 14 and 15) of an air supply system (12) to the retarder and being arranged to operate sequentially to control progressively magnitude of power supplied to the retarder if the vehicle speed is not reduced during sequential periods of predetermined duration.

Abstract: Apparatus for controlling movement of a heavy vehicle used in the mining and construction industries comprises a radar scanner (30) and an infra red detector (31) mounted at the rear of the vehicle for detecting a hazard in the path of the vehicle while reversing and a control system (10) responsive to the detection devices (30, 31) for controlling supply of air in a pneumatic supply system (11) of a retarder of the vehicle when a hazard is detected by the detection means (30, 31). The control system (10) includes driver operable apparatus (19, 23 and 40) for releasing the retarder.