Dual-circuit braking system, suitable for trailers - employing dual relay valve controlling both circuits

摘要

Each circuit includes a brake actuator, pressure reservoir and control valve, as known in air brake systems for trailers of articulated vehicles. The reservoirs are charged from a common pressure supply such as a compressor on the tractor and the valves are now economically combined in a dual relay valve, so as to be operated by respective pistons or other members responsive to a control pressure exerted on both. Conveniently the pistons are opposed, so a control pressure chamber can be formed between them, and the arrangement allows automatic emergency braking for failsafe purposes.