Patent GB-342756-A (GB)
Title: Improvements in or relating to brake mechanisms
IPC: B60T13/16
Filed: 1929-11-04
Abstract: 342,756. Fluid - pressure brakes. STAUDE, E. G., 2675, University Avenue, West, St. Paul, Minnesota, U.S.A. Nov. 4, 1929, No. 33541. Convention date, July 3. [Class 103 (i).] In a braking system of the kind in which a pump circulates fluid in a closed path and valve means are provided for controlling the flow of fluid so as to produce a pressure in the system to operate the brakes, a gear wheel pump is used having relatively small gears (about three-eighths of an inch pitch diameter) which are driven at a velocity of the order of ten thousand revolutions per minute, as by a small electric motor or a turbine driven by the vacuum at the intake of the vehicle engine. The pump, motor and brake operating piston are embodied in a self-contained unit 9 movably supported by links 11 pivoted on the pedal shaft 14, and comprising an adjustable rod 27 pivoted to the pedal 6 at 7 and having an enlarged portion 30 tapered to form a valve 31 adapted to engage a seat 39 formed on a piston member 37 slidable in the bore 36 of the casing. A further enlargement 32 on the rod 27 forms an abutment for a spring 41 tending to open the valve 31, and the piston member 37 is threaded internally at 40 to take a member 33 connected at 28 to the brake rod 8. The rear portion of the piston member 37 is reduced to form an annular passage 42 communicating by a passage 55 with the bore 38 of the piston member. While the valve 31 is open fluid is circulated by the gear wheel pump 43, 44 around the circuit formed by the passages 52, 42, 55, 38, 36, 48, and 53. Depression of the pedal 6 closes the valve 31 and the piston member 37 is moved by the pressure built up behind it to apply the brakes. The pressure also acts on the enlarged portion 32 of the rod 27 to tend to open the valve 31 and exert a reaction upon the pedal. A check valve 47, Fig. 8, is provided in a byepass 50 to allow the brake to be operated if the pump gears 43, 44 stop. The rod 27 is drilled at 59, 60 to provide an outlet for fluid which may collect between the members 32, 33, and leakage at the points 62, 63 is also returned by a passage 61 to the bore 36. The pump gears are driven by pinions 66, 67 from a small electric motor 69 the circuit of which is closed, when the pedal is depressed, by a loose sleeve 72 normally held away from contact terminals 82, 83 by nuts 73, 74 on the rod 27 but moved by a spring 75 to contact with the terminals when the rod 27 is moved to the left by the pedal. A plug 88 is provided for filling the chamber 36, and the rods 27, 33 pass through stuffing-boxes 64,90. Fig. 10 shows a modification in which the pedal acts on a valve rod 93 through levers 108, 105, closing the valve 92 against a movable valve seat 94 to stop the circulation through channels 52, 113, 96, 98, 99 and cause the member 91 to be moved to assist the manual effort in rocking the brake shaft 111. The check valve is dispensed with by providing a reservoir 112 into which fluid displaced by the movable valve members may pass if the pump is inoperative. The movable valve seat may be formed in the master piston 131, Fig. 16, of a hydraulic brake system in which the pedal 6 is connected by the rod 27 to a push rod 119 carrying electrical contacts 125 and integral with a member 122 having a valve 128 co-operating with a seat 129 on the master piston 131, the cylinder 135 of which is connected by a pipe 147 to the brakeactuating devices. To replenish the fluid a reservoir 136 is connected with the cylinder 135 by a port 137 and also by passages 143, 138, 139, 154, 153 and 152. The pump gears may be driven by a turbine 156, Fig. 20, actuated by the vacuum in a chamber 159 connected to the intake manifold of the engine by a pipe 164 having a check valve 163. Air is drawn through inclined ports 158 arranged in a circle and across inclined vanes 157 on the turbine rotor 156. Removal of the foot from the accelerator control closes the throttle and causes sufficient vacuum to raise the check valve 163 so that the turbine is driven only when braking or at low speeds.