Patent GB-236193-A (GB)
Title: Improvements in fluid-pressure actuated brake mechanism
IPC: B60T13/24
Filed: 1925-06-08
Abstract: 236,193. Bragg, C. S., and Kliesrath, V. W. June 26, 1924, [Convention date]. Brakes, arrangement and disposition of and braking; relay and power apparatus. - Fluid - pressure brake mechanism applicable to motor vehicles comprises a pair of pistons working in a common cylinder respectively connected to two sets of brakes for example the front and rear brakes of the vehicle and adapted to be moved by fluid-pressure in both directions step by step to graduate the action under the control of a reversing valve the co-operating members of which are actuated respectively by a pedal or equivalent and one of the pistons. The fluidpressure may be furnished by the suction or compression or both of the engine of the vehicle. The operation of one piston may be prevented or delayed. One of the pistons may be directly actuated by the valve connections in the event of failure of the power. The pistons 110, 110<a> working in the fixed cylinder 101 have tubular rods 112, 112<a>, connected respectively by links 62, 63 to the brake shafts of brakes 52 on the front and rear wheels of the vehicle. The end chambers B<2>, B<3> normally communicating by a pipe 170 and the central chamber A<1> of the cylinder are adapted to be connected with the atmosphere' and with the intake manifold 21 of the engine preferably through a tank 23a to effect the application and release of the brakes by a valve mechanism comprising a sleeve 116, 116<a> sliding in the piston rods and connected by a cross-bar 174 passing through a slot in the piston rod 112 and by rods 171 to the pedal 50. The sleeve part 116 is open to the atmosphere by ports 143 and is provided with ports 25, Fig. 4. The sleeve part 116a is adapted to be opened to the vacuum tank 23<a> by a valve 118 and is provided with ports 24. The central boss of the piston 110 is provided with chambers 28, 30 in which slide collars 29, 27 secured to the valve sleeve 116, 116<a>. The seat of the valve 118 is fixed to the piston rod 112a and the valve proper has a lost motion connection by means of a rod 109 and a slot 119<a> with the sleeve part 116<a>. Normally the parts are in the position shown whereby the cylinder chamber A<1> is open to atmosphere through the passage 40, Fig. 4, and ports 25 and the chambers B<2>, B<3> are connected by passage 36 and ports 24 to the sleeve 116<a> which is closed by the valve 118. If the pedal 50 is moved to apply the brake. the sleeve 116, 116a is moved' to the left thereby permitting the valve 118 to open and bringing the ports 24, 25 respectively into communication with the cylinder chambers A<1> and B<2>, B<3> whereby the pistons 110, 110<a> are moved towards each other and the brakes are applied. The movement of the piston 110, however, causes the ports 24, 25 to be covered and thus the application can be graduated by successive movements of the pedal. If the pedal is permitted to return the chambers B<2>, B<3> and A' are respectively connected to the vacuum tank 23a and to the atmosphere so that the brakes are positively released and the release action may be graduated in a similar manner to the application. If the power should fail the rear brakes may be directly applied by the engagement or the collars 27, 29 of the valve with the piston 110. The operation of the piston 110<a> and the front brakes connected therewith may be delayed by the provision in the pipe 170 of a non-return valve 181 which prevents the flow of atmospheric air into the cylinder chamber B<3> necessary to permit the operation of the piston until the pedal has been moved sufficiently to open the valve by the engagement therewith of a cam 184 and the rod 171. Alternatively the rod 112a of the piston 110<a> may be provided with a recess for engagement by a spring detent mounted in the cylinder head 102 such detent yielding to permit movement of the piston only when the degree of vacuum established in the cylinder chamber A<1> has reached a predetermined value.