Patent GB-262448-A (GB)
Title: Improvements in brake mechanism for automotive vehicles
IPC: B60T13/24
Filed: 1926-04-12
Abstract: 262,448. Bragg, C. S., and Kliesrath, V. W. May 19, 1925, [Convention date]. Fluid-pressure. -- Relates to fluid-pressure brake mechanism, particularly for heavy motor vehicles and trailers, comprising a main brake cylinder and one or more auxiliary brake cylinders, each of which comprises a double-acting piston, the main cylinder being under the control of reversing valve mechanism and passages being provided to connect the main cylinder and the auxiliary cylinder or cylinders on opposite sides of the pistons, so that all the cylinders are controlled by the reversing valve mechanism. The pistons of the main cylinder 1, Fig. 1, and the auxiliary cylinder 51, or one of the auxiliary cylinders, are connected axially. An additional auxiliary cylinder containing two pistons may be embodied in the apparatus. The valve mechanism is connected with the main cylinder piston by means permitting lost motion whereby the operator may apply his physical force to the brakes. The piston 3 of the main cylinder and the piston 52 of the auxiliary cylinder are carried on a hollow piston rod 5. The valve mechanism is provided in the hub 10 of the piston 3 and comprises valves 40 - - 43, Fig. 2, slidably mounted on a valve-actuating sleeve 20 which passes through the piston rod 5. Operation of the pedal lever which is connected to a lug 25 on the end of the sleeve 20, opens valves 41, 43 by collars on the sleeve. Communication is thus opened from the intake manifold of the vehicle engine through a pipe 62, part of the sleeve 20, aperture 24, suction chamber 17, past the valve 41, and through a port 34 to one side of the piston. The other side of the piston is put into communication with the atmosphere, through the open end 29 of the valve sleeve 20, apertures 27, past valve 43, and through a port 36 to the other side of the piston. The pressure differences produced on opposite sides of the piston in the main cylinder are also produced in the auxiliary cylinder through pipes 42<g>, 42h, and the brakes connected to lugs 30 on the piston rod are applied. When the movement of the foot lever and the sleeve 20 stops, the piston continues to move forwards till the valves 41, 43 close and the piston is held in balanced position. On release of the foot lever, the valves 40, 42 are opened by the sleeve 20, thus reversing the connections of the suction pipe and the atmosphere to opposite ends of the cylinders 1, 51, a passage 19 providing communication with the atmosphere, and the pistons are returned to " off " position. A partial vacuum is maintained in these cylinders on both sides of the pistons when the brakes are released by means of a pipe 42f connected to the pipe 62, and pipes 42<a>, 42<g> controlled by a valve 42<c> opened by a pin 42e struck by the piston of the auxiliary cylinder when in retracted position. The lost-motion connection between the valve sleeve 20 and the piston rod consists of a collar 26 on the valve sleeve located in a recess in the piston rod. An adjustable restricting valve, a check valve, and an outwardly-opening vent valve on the check valve are provided in the pipe connecting the intake manifold of the vehicle engine with the valve-actuating sleeve to prevent interference with the operation of the engine. The application of the invention to six-wheeled vehicles is described and shown. Brakes for a trailer are operated by an auxiliary cylinder mounted on the trailer and connected to the main cylinder by pipes having flexible portions. Specification 245,444 is referred to.