GB595520A - Fluid pressure transmission system - Google Patents

Abstract

595,520. Brakes. SCHNELL, S. July 5, 1945, No. 17204. [Class 103 (i)] A fluid-pressure system, described as applied to a brake, comprises a pedal-operated mastercylinder A, brake-actuating cylinders 10 and an interposed booster unit C containing connected pistons 18, 19 working respectively in large and small cylinder bores. When the pedal is first operated, the resultant pressure is communicated through the passages 24, 31, space 16 and pipe 11 to the brake cylinders. The pistons 18, 19 do not move as the area of the piston 19 is greater than the area of the piston 18 within the sealing ring 25, and the pressure tends to keep the piston 18 seated on the ring 25. When the master cylinder pressure rises sufficiently, it lifts the valve 47 and admits the pressure through the passage 42 to the outside of the ring 25, and at the same time, through the passage 40 to the space 41. This moves a piston 30 to abut on a valve seat 34 which closes the passage 31. Continued actuation of the pedal at the high pressure, therefore, moves the piston 18, 19 to the left bv the master cylinder pressure acting on the whole of the area of the piston 18, the pressure transmitted to the brake cylinders being correspondingly higher according to the relative areas of the pistons 19, 18. A constriction 45 in the passage 44 leading to the valve 47 prevents a sudden initial actuation of the pedal from opening the valve and bringing the booster immediately into operation.