All the mechanisms controlling the operation of the system and supplying the air are located on the truck tractor. The trailers of the combination are equipped only with the mechanisms for their own braking purposes. Compressor 1 delivers compressed air to tank 2. Relief valve 3 maintains a constant air pressure in the system. Tank 2 is connected by a pipeline to emergency valves 9 of the trailers. Brake valve 5, connected to tank 2, admits compressed air to brake chambers 6 of the rear wheels, through rapid-release valve 7 to brake chambers 8 of the front wheels and to acceleration valves 10 of the trailers. When no braking action is required, compressed air is delivered from the tank through emergency valve 9, operating in conjunction with acceleration valve 10, to supplementary tank 11. When the pedal of brake valve 5 is depressed, compressed air is delivered to the brake chambers of the front and rear wheels of the truck tractor and, simultaneously, to acceleration valves 10 of the trailers. Acceleration valves 10 admit air from supplementary tank 11 and main tank 2 to brake chambers 12 of the trailers. The whole truck-trailer combination is braked simultaneously. Air is discharged from brake chambers 12 of the trailers, when the brakes are to be released, through acceleration valves 10. Air is discharged from the rear brake chambers of the truck tractor through brake valve 5; air from the front brake chambers is discharged to the atmosphere through rapid-release valve 7. Pressure regulator 4 switches the compressor over to idle running. If trailers break away from the combination, the pipeline leading to the acceleration and emergency valve is ruptured, cutting off the air supply from the truck tractor. Then the trailers are braked by the reserve air from supplementary tank 11, which passes through the acceleration and emergency valves to the brake chambers, performing the braking operation.
$4297$CHP,Br$