Patent GB-246185-A (GB)
Title: Improvements in and relating to brake mechanisms
IPC: B60T11/12
Filed: 1926-01-19
Abstract: 246,185. Compagnie Internationale des Freins Automatiques. Jan. 19, 1925, [Convention date]. Fluid-pressure.-To maintain constant the stroke of the actuating member of a brake mechanism a quantity of liquid, which is prevented from returning, is supplied to the cylinder of a piston connected to the mechanism when the actuating member has completed a predetermined stroke. A device may also be included for returning liquid to the reservoir if the brakes should be applied before the predetermined stroke has been completed. As shown in Fig. 2, pistons 5, 7 are connected at 6<1>, 2<1> to a floating lever 1<1> and the lever 1 is connected to the cylinders 4, 8 of the pistons, the levers being connected to the brakes at their other ends. A reservoir 14 communicates by oppositely acting non-return valves 15, 16 with the cylinder 4. Actuation of the piston 5 by fluid supplied to the left hand side thereof forces liquid through conduits 20, 11 into the cylinder 8 to actuate also the piston 7. When a predetermined stroke of the piston 5 has been completed, the conduit 20 is closed, but if the brakes are not applied liquid is still forced into the cylinder 8 through the conduit 11 and non-return valve 12, such additional liquid being thus unable to return when the brakes are released. As scon as the brakes are applied, liquid is forced into the reservoir 14 through the valve 15. Fig. 1 shows apparatus comprising pistons 13, 18 of different areas, and in which only the piston 18 is effective after a predetermined stroke has been completed whereby the brakes are rapidly brought into engagement and then applied with an increased pressure. The cylinder 20<1> is provided with an enlarged part 20. During the initial part of the application stroke the liquid displaced by both pistons 13, 18 passes through the cylinder 20<1> to actuate the piston 57 connected to the brakes. After the piston 18 has entered the cylinder 20<1> liquid displaced by the piston 13 continues to enter this cylinder through a conduit 9 and a non-return valve 12 if the brakes are not applied. The application of the brakes, hcwever, causes the pressure in the system to rise and the valve 12 to close and the piston 18 only is then effective to apply the pressure to the brakes. Any further liquid displaced by the piston 13 enters the reservoir 14 through the valve 15. During the return stroke and until the piston 18 reaches the enlarged part 20 of the cylinder 20', the piston 13 draws liquid into the system from the reservoir 14 past the valve 16. If the brakes should be applied before the piston 18 enters the cylinder 20<1> the excess of liquid in the system is returned to the reservoir 14 through the valve 15. The Specification as open to inspection under Sect. 91 (3) (a) includes also the following subject-matter :-A spring interposed between the piston 13, 18, Fig. 1, may be provided to perform the function of the valve 15 to enable the piston 18 to reach the predetermined point should the shoes be applied before that point is reached. The arrangement shown in Fig. 1 may be used with the piston 57 acting as the operating piston and the pistons 13, 18 connected to the brakes, the valve 12 being dispensed with. Fig. 1 (Cancelled) shows an apparatus similar to that shown in Fig. 2, but in which the single conduit 11 connects the cylinders 4, 8. When the piston 5 reaches a predetermined point a passage 10 therein registers with the conduit 11 and liquid is then forced into the cylinder 8 past the non-return valve 12 if the brakes are not already applied. The piston 5, instead of forming the valve, controlling the supply to the cylinder 8 may actuate a valve controlling a supply chamber separate from the cylinder 4. Fig. 2 (Cancelled) shows a system in which a piston 18 is actuated to force liquid into the cylinder 57<1> of a piston 57 connected to the brake mechanism. In this case, when the piston 18 has completed the predetermined stroke, a cam 19 on the piston rod opens a valve 10 whereby liquid under pressure is admitted from a reservoir 9 to the space between the pistons to complete the application movement of the mechanism if this has not already been effected. The reservoir 9 may be replaced by a pump actuated during the whole or part of the stroke of the brake applying piston. The delivery stroke of the pump mav be produced by a spring put under tension during the return movement of the mechanism or the pump may be actuated by a cam, means being provided in this case to provide for the flow of liquid that continues to be delivered by the pump after the shoes are in contact with the wheels. This subject-matter does not appear in the Specification as accepted.