Patent GB-276636-A (GB)
Title: Improvement in brake mechanism for automotive vehicles
IPC: B60T13/24
Filed: 1927-07-14
Abstract: 276,636. Bragg, C. S., and Kliesrath, V. W. Aug. 30, 1926, [Convention date]. Fluid-pressure.-A fluid-pressure brake system for motor vehicles comprises a main actuator connected to one set of brakes an auxiliary actuator connected to another set of brakes, for example brakes on a trailer vehicle a pressure difference being established in the auxiliary actuator equal to that in the main actuator by means of valve mechanism controlled by the pressure in the main actuator. The system comprises a main actuator 1 on the propelling vehicle A and an auxiliary actuator 101 on the trailer B, the pistons of both actuators being normally subject to a vacuum on both sides produced by the suction of the engine, the application of the brakes operated by both pistons being effected by operating the valve mechanism of the main actuator to admit air to one side of the main piston, thereby causing the valve mechanism of the auxiliary actuator to be actuated to admit air also to one side of its piston. The main actuator, Fig. 3, is of the double-acting type as described in Specification 259,189, [Class 135, Valves &c.], comprising a tubular valve rod 20 sliding in the piston-rod 5, 5<a> and connected to the pedal 88. The rod 20 carries two pairs of suction and air inlet valves 40, 41 and 42, 43 urged apart by interposed springs and actuated by collars fixed to the rod. The vehicle is connected by the pipe 65 to the intake pipe 61 of the engine. Air has access to the valve chamber by way of the piston-rod 5, 5a and by the right hand part of the valve rod 20 beyond the plug 21. The auxiliary actuator, Fig. 4, is single acting and comprises a, piston-rod 105, 105<a> within which slides the valve rod 94 connected to a sleeve 120 which carries the suction and air inlet valve 142, 143. A passage 134 connects the left hand chamber of the cylinder with the valve chamber and air has access to this chamber by the aperture 105b and the hollow piston-rod. A port connects the valve chamber to the right hand piston chamber. The valve rod 94 is connected to a flexible diaphragm 91 the chambers 92, 93 of which are connected respectively by pipes 98, 97 with the right hand chambers of the auxiliary and main actuators. A non-return or flap valve between the chambers 92, 93 is formed by the piece 96 which covers an aperture in the diaphragm. Normally the suction valves 41, 42 of the main actuator are unseated so that both of the chambers thereof are exhausted by way of the pipe 65. The right hand chamber of the auxiliary actuator is also exhausted by way of the pipe 98, the flap valve 96 and pipe 97 and the left hand chamber is constantly exhausted by way of the pipe 65<a> connected to pipe 65. If the pedal 88 is depressed to apply the brakes, the suction valve 41 of the main actuator remains open, the suction valve 42 is closed and the valve 43 is opened to admit air to the right hand chamber of the actuator, thus applying the brakes on the propelling vehicles. The consequent rise of pressure in the chamber 93 of the valve actuating device of the auxiliary actuator causes the valve rod 94 thereof to be shifted to the left thereby opening the valve 143 and admitting air to the right hand chamber of the actuator which thus applies the trailer brakes. As soon as the movement of the pedal ceases, the slight continued movement of the main piston 3 closes the air inlet valve 43 and the consequent equalization of the pressure in the chamber 92, 93, Fig. 4 permits the valve 143 of the auxiliary actuator to close thus holding the trailer brakes applied with a pressure equal to that on the propelling vehicle. To partially release the brakes the pressure on the pedal is slightly relieved permitting equalization of the pressure in the main actuator chambers through the apex valves 41, 42. The reduction of pressure transmitted to the chamber 93, Fig. 4 opens the valve 96 and if the pressures are sufficiently great will flex the diaphragm 91 and open the valve 142 producing a corresponding equalization of pressures in the auxiliary actuator. If the pedal is allowed to return to effect the complete release of the brakes, the valve 40 of the main actuator is opened to admit air of the left hand chamber thereof and the valve 42 is further opened to exhaust the right hand chamber and the reduction of pressure in the valve control chamber 93 of the auxiliary actuator opens the suction valve 142. A check valve 65<c> is disposed in the pipe 65<a> leading to the auxiliary actuator so that in the event of detachment of the trailer and breakage of the pipes the vacuum in the one chamber will be maintained and the admission of air to the other chamber will effect the application of the brakes. Extensions 67<c>, 97<a> of the pipes are shown for connection to other actuators. Non-return and restricting valves 67, 66 are shown in the pipe 65. A cylinder and piston device may be used instead of the diaphragm 91 for controlling the valves of the auxiliary actuator. The main actuator may be of the single acting type in which case the suction pipe 65 is connected directly to the left hand chamber thereof and only one pair of valves is provided. According to the Specification as open to inspection under Sect. 91 (3) (a) the invention may be applied to actuators in which the control valve mechanism is located exterior of the cylinders. This subject-matter does not appear in the Specification as accepted.