Safety pneumatic brake servo valve for trailers - has outlet to trailer brakes with controlled pressure distributed by sprung piston in hollow casting

摘要

The servo valve for pneumatic trailer brakes has a piston housed in a hollow casing. The control fluid pressure from the brake pedal enters through a gland (22) and the main pressure from the main air reservoir enters through another gland (18). The pressure transmitted to the wheels through the servo valve is proportional to the control fluid pressure. A separate air reservoir is mounted on the trailer and is continually topped up by a non-return valve. If the brake pipe to the trailer is severed, the trailer brakes are automatically applied by the second reservoir and the servo valve prevents loss of air through the broken pipe from the main reservoir.