GB587591A - Fluid pressure brake actuating system - Google Patents

Abstract

587,591. Motor-vehicle steering gear. BOLDT, W. F. Sept. 27, 1944, No. 18472.. [Class 79 (ii)] In a vehicle wherein steering is assisted by differential braking, a single ' brake control lever is arranged so that symmetrical or differential braking is obtained according to the direction in which the lever is moved. As described, the lever 79 is in a unit controlling the admission of compressed air from the pipe 4 to either, or both, of pipes 6, 7 leading to units where the air pressure is used to generate hydraulic pressure for application to the brake cylinders. The lever 79 is slidable longitudinally of a valve casing along a slot 80, and transversely along a slot 85, and is provided with projections 81, 82 which abut on a ring 83 bearing on valve stems 51, 57. The lever is pivoted at 78 to a plunger 39, one face 77 of which is of camform to re-act with a correspondingly shaped stationary face 76. A spring-pressed member 84 and a light spring 86 secured to the end of the lever tends to maintain the lever in its neutral position. When the lever 79 is moved transversely along the slot 85, the cam faces 76, 77 act to push the plunger 39 against the pressure of springs 40, 38, but no off-centre force is exerted on the ring 83 so that both valves 47, 48 are inoperative as regards the passages 43, 44. This permits air pressure from the passage 29 to pass equally through pipes 6, 7 to the two sets of brake actuating means. If the lever 79 is moved to the left along the slot 80, the plunger 39 is again pushed forward, but the lever fulcrums on the lower projection 82 and the off-centre force on the ring 83 closes the valve 48 to seal the passage 44. This results in an application of the left-hand brakes, and owing to the self-lapping characteristics of the valve assembly 31, 35, 36, 39, the intensity of the application depends on the extent of movement of the lever 79 to the left. If application of the right-hand brakes is required, the lever 79 is moved to the right to fulcrum on the upper projection 81 and, by tilting the ring 83, to move the valve 47 to seal the passage 43. For normal simultaneous brake applications, a pedaloperated valve is provided which admits pressure equally to the pipes 20', 20". The plungers 64, 69 are thus forced to the left to seal the passages 60, 62 and the pressure is supplied equally to the pipes 6, 7.