Patent GB-308714-A (GB)
Title: Improvement in hydraulic brake system for automotive vehicles
IPC: B60T13/24
Filed: 1929-02-18
Abstract: 308,714. Bragg, C. S., and Kliesrath, V. W. March 27, 1928, [Convention date], Fluid-pressore, - A fluid pressure brake system for vehicles comprises a power cylinder or actuator the piston of which may be operated by the suction of the driving engine of the vehicle and is arranged to apply pressure to the wheel brakes through hydraulic transmission mechanism, the system being such that the operator can apply his physical force to the brakes of the non-steering wheels only by the pedal &c. by which the valve mechanism of the power actuator is controlled. The system shown in Figs. 1, 2. and 5 comprises a cylinder 1 the piston 3 of which is operated by the suction of the engine under the control of a valve mechanism such as described in Specification 267,478, comprising a casing 10 connected by link 76 to a pedal 77 and in which is slidably arranged a sleeve 20 carrying valves 40, 41 urged apart by a spring 42 and actuated by collars 40a, 41a on the sleeve. The casing has connections 26, 12, 32 respectively with the engine suction pipe 62, the atmosphere and the cylinder 1. The rod 5 of the piston 3 is secured to a piston 83 working in a hydraulic cylinder 80 in which also works a piston 82 connected to the valve sleeve 20. The cylinder 80 communicates by a pipe 57 with the brake cylinders 52 of the rear wheel brakes and by the piston rod 5 and pipe 56 with the cylinders 50 of the front or steering wheel brakes. The parts are normally in the position shown in which the suction valve. 40 is seated and the air inlet valve 41 is open so that the cylinder 1 is open to atmosphere. By depression of the pedal 77 to apply the brakes, the valve casing 10 is moved to close the valve 41 and open the valve 40 so that the cylinder 1 is connected to the engine suction pipe 62 and the pistons 3, 83 and 82 thereby actuated to force liquid from the cylinder 80 into the brake cylinders 50, 52. If the pedal movement is stopped, the slight continued movement of the piston 82 and thus of the valve sleeve 20 relative to the valve casing effects the closure of the valve 40 while leaving the valve 41 closed so that the brakes are held applied. The valve casing 10 can also be caused to abut against a collar 28 on the valve sleeve 20, whereby the operator may apply a direct effort to the piston 82 and thus through the liquid in the pipe 57 to the rear wheel brakes in addition to, or if the power should fail, in substitution for, the effort applied by the piston 3. In an alternative system, Fig. 4, the power piston 103 controlled by similar valve mechanism 110 to that shown in Fig. 5, and pedal 177 is connected to hydraulic pistons 182, 183 by a floating lever 190. The hydraulic cylinders 180, 180<a> have pipe connections 156, 157 respectively with the brake cylinders of the front and rear wheels. The valve sleeve 120 is connected by link 191 and lever 192 pivoted at 193 to the pivot 190<c> of the lever 190 at which this lever is connected to the piston 182. The cylinder 180<a> is slidably mounted on the chassis, its movement in one direction being limited by stops 180<b> and it is connected by lever 187 and link 186 to the valve casing 110. The system functions in a similar manner to that shown in Figs. 1 and 2 with the exception that the pressure in the hydraulic cylinder 180<a> reacts through the lever 187, and valve casing 110 on the foot of the operator who thus receives an indication of the pressure applied to the brakes. The movement of the cylinder 180<a> by the pedal also forces liquid into the brake cylinders. The direct effort of the operator is applied to the rear wheel brakes through the link 191 and lever 192. In a further arrangement, Fig. 8, the power cylinder 301, the vacuum in which is controlled by a valve mechanism 310 as above described, and the two hydraulic cylinders 380, 380<a> are slidably mounted and are connected to a bar 390 normally held against stops 390<c> by springs 390<b>. The valve sleeve 320 is connected by a cable 391, passing over a pulley 392 on a second movable bar 390<a>, to the bar 390. The pistons 303, 382, 383 are connected to the bar 390<a>. When the cylinder 301 is exhausted by operation of the valve 310 it and the cylinders 380, 380<a> are moved, forcing liquid through pipes 356, 357 into the front and rear brake cylinders respectively. The operator can also apply a direct effort to the cylinder 380<a> through the valve casing and sleeve and the cable 391. The power actuator may be single or double acting and its piston may be normally subject on both sides to vacuum or to the high pressure fluid. According to the Specification as open to inspection under Sect. 91 (3) (a) the actuator may, for example, be of the kind illustrated in U.S.A. Specifications 1,583,117 and 1,582,118. Further, one or other of the bars 390, 390<a>, Fig. 8, may be fixed. This subject-matter does not appear in the Specification as accepted.