GB331700A - Hydraulic brakes - Google Patents

Abstract

331,700. Coatalen, L. July 12, 1929. Fluid-pressure. - In hydraulic brake mechanism having a separate pressurecreating means and pipe line system for each brake or set of brakes a duct is provided for interconnecting the systems to equalize the pressures by means operative only when the pressures are effective to apply the brakes, the duct being closed between anv two systems when the pressure in one of them fails, so that the other brakes are not rendered inoperative. As shown three master cylinders 2 are arranged side by side each containing a piston 4 moved by a finger 5 on a shaft 6 turned by the brake pedal or hand lever, the pistons being moved simultaneously. The outlet pipe 7 from each cylinder is connected to a brake or set of brakes and communicates with the cylinder by passages 30 and a valve chamber 11 the valves 14 each having a needle portion 31 pressed by a spring 15 on a seating at the end of an axial passage 27 in an abutment 24. The passages 27 communicate with each other by a compensating duct 13. When the master cylinders 2 are operated the valves are lifted by the pressure acting on the cups 23, the opening movement being limited by flanges 17 formed on caps 16, and the pressure in the pipe lines 7 is equalized by the duct 13. If a leak occurs in one pipe line the valve 31 associated with that pipe-line closes, the pressure from the other cylinders acting through the bore 27 not being sufficient to overcome the spring 15. The valves may be arranged in a unitary body, closing caps 29 being spaced slightly from the abutments 24 to provide chambers communicating with the axial passages 27 and the compensating duct 13. The passages 30 connecting the cylinders with the pipes 7 are partly formed in bored bolts 32. The arrangement shown may be applied to six-wheeled vehicles or vehicles with a transmission brake in addition to wheel brakes. Each valve chamber may be connected to the oil reservoir 18 so that any oil leaking past the valve returns to the reservoir. The piston may be operated by separate pedals and one of the pedal shafts may be capable of hand operation. In modifications the compensating duct 13 opens directly into the valve chambers 11 and the needle valve 31 is omitted.