GB385410A - Improvements in or relating to fluid pressure braking systems - Google Patents

Abstract

385,410. Fluid-pressure brakes. BOUGHTON, E. B., EMMOTT, W., and BROCK, D. T., (trading as AUTOMOTIVE PRODUCTS CO.), Brock House, Langham Street, London. Nov. 28, 1931, No. 33054. [Class 103 (i).] In a hydraulic vehicle brake having manually operated low and high pressure pistons in a master cylinder unit 56 for taking up slack and applying pressure respectively and a valve automatically rendering inoperative the low pressure piston and rendering operative the high pressure piston when the slack in the system is taken up, an operative connection of a source of power with the master cylinder is controlled by a speed control of the vehicle. In one modification the speed control is the brake pedal which has a tread mounted on a slidable plunger adapted to actuate by means of Bowden wire the valve of a fluid pressure bellows connected to the brake pedal. In a further modification the accelerator pedal 72 when released is adapted to connect a brake cylinder 51 to a source of power, pipe 71, by means of a valve 58, and thus operate the pedal 54 with sufficient power to take up slack in the brake transmission by means of the low pressure cylinder of the unit 56. When the pedal 54 is then depressed by foot pressure for normal braking this pressure is just sufficient to cause the usual change-over valve of the unit 56 to function and allow the brake cylinder pressure to be applied to the brakes through the increased leverage provided by the high pressure cylinder of this unit 56. Greater force is applied to the pedal 54 by the foot for severe braking. To release the brakes when the pedal is released a valve 59 is provided in the brake cylinder supply pipe 69, 70 adapted to be opened when the pedal 54 approaches release position by a cam 79 on the pedal spindle, to connect the pipe 70 to atmospheric openings 68. The cam 79 engages a pin 80 on the valve stem and when the pedal is in release position the cam is clear of this pin and the atmospheric openings 68 are closed, and when the pedal is moved for application of the brakes the inside of the cam engages the left-hand side of the pin 80 and merely extends the two spring telescoping sections of the valve stem. Power may be derived from the intake manifold of the vehicle engine or an air compressor.