Patent GB-200503-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T8/18
Filed: 1923-06-27
Abstract: 200,503. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Compagnie des Freins Westinghouse). July 5, 1922, [Convention date]. Fluid-pressure.-Relates to apparatus of the kind comprising a supplementary brake cylinder for augmenting the action of the, main brake cylinder when the vehicle is loaded, and consists in the provision of a valve 'between the two brake cylinders, influenced by pressure in the auxiliary reservoir or other source of fluid-pressure, and so arranged that when fluid under pressure is vented from one side by manually-operated means, the valve is moved to a position to establish communication between the source of fluid-pressure and the supplementary brake cylinder, and to be retained in that position as long as a predetermined degree of pressure is maintained in the source of fluid-pressure. Fig. 1 shows the general arrangement, wherein 1 indicates the main cylinder, 4 the triple-valve, 3 the train pipe and 6 the auxiliary reservoir. A pipe 7 branched at 8 leads from the triple valve to the main cylinder by a pipe 9 and to the valve 11 by a pipe 10. A pipe 19 leads from the auxiliary reservoir to the valve 11, and a pipe 20 leads from the valve 11 to the supplementary cylinder 21, which is provided with the known slack-adjusting device 22-24. The valve 11 is manually set for operation by means of levers 12-18, a catch 56 being provided to lock the handle 18 in the braking-position for a loaded vehicle when necessary. The body 51, Fig. 2, of the valve 11 contains a slide valve 27 controlled by the stem of a piston 26 subject on one side to the pressure of a spring 30 and on the other to the auxiliary reservoir pressure through the pipe 19. A casing 52 carries a valve 28, normally held closed by its spring 29. The slide valve 27 controls communication with passages 38, 40 in a plug 43 which forms one seat of a valve 41 normally closed by a spring 42. With the ports in the position shown, corresponding to the unloaded condition of the vehicle, fluid from the auxiliary reservoir passes through ports 31, 32 and keeps the piston 26 and slide valve 27 in position to isolate the cylinder 21. When the valve 28 is opened by the levers 12-18, fluid escapes from the chamber B to the chamber C and through the port 33 to atmosphere. The piston 26 and slide valve 27 are now moved to the right, and orifices 35, 36 register with the passages 38, 39, which are thus placed in communication. The orifice 39 being connected to the main cylinder by pipes 10, 9, communication may be established between the cylinders 1, 21 through the cavity 40, port 45, passage 46 and pipe 20, when the valve 41 is opened against the pressure of its spring 42 and is caused to seat on the member 44. The supplementary cylinder is thus brought into action when the brakes are applied. When the brakes are released, the cylinder 1 exhausts to atmosphere and the cylinder 21 exhausts through the passages 46, 45, 40, 38, 37, 39 to the cylinder 1, until the valve 41 rises, when its exhaustion is completed through the passages 46-48 and the atmospheric passage 49. If the auxiliary reservoir pressure falls below a predetermined value, the spring 30 returns the piston 26 to its initial position and the slide valve 27 isolates the cylinder 21. The spring 29 is then free to close the valve 28, unless the catch 56 retains the handle 18, and the ports are then in position corresponding to the unloaded condition of the vehicle. The valve 11 may be mounted on the supplementary cylinder, and a second auxiliary reservoir, controlled by the valve 11, may be provided, if necessary.