Patent GB-354423-A (GB)
Title: Improvements in and relating to variable load braking apparatus
IPC: B60T15/02
Filed: 1930-05-21
Abstract: 354,423. Fluid - pressure brakes. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross. London.-(Assignees of Compagnie des Freins Westinghouse; 23, Rue d'Athenes, Paris.) May 21, 1930, No. 15683. Convention date, May 22, 1929. Addition to 348,147. [Class 103 (i).] In the apparatus of the parent Specification the supply of pressure fluid to the valve mechanism controlling the braking action is controlled by an abutment arranged to be moved by a spring to a position limited by the degree of compression of the vehicle springs this action being opposed by the pressure in the train pipe or other selected part of the system. The abutment comprises differential pistons 26, 27 adapted to be moved to the right to bring the arm 36 of a bell crank into engagement with the vehicle spring box 37 by a spring 46 when the pressure on the train pipe is below a certain value. When the vehicle is unloaded the pistons move a slide valve 28 to such an extent assisted by the action of a spring ball 47 on an incline on the valve that a cavity 41 in the slide valve connects the train pipe 4 past a ball valve 40 to a pipe 24 leading to the valve mechanism controlling the braking action and train-pipe pressure is admitted to chamber 21, on the left of piston 14, of this mechanism. Train-pipe pressure is also supplied through a passage 23 to the right-hand side of the piston 14 and a spring 20 moves the piston 14 and a slide valve 15 to the right-hand position. When the vehicle is loaded the pistons 26, 27 and the slide valve 28 are not moved so far to the right and the pipe 24 is connected to atmosphere through a cavity 43, the chamber between the pistons 26, 27 and by leakage past the piston 27. The piston 14 and the slide valve 15 are thereupon moved to the left by the charging pressure fluid in the chamber 22 supplied from the train pipe through the triple valve 1 and the passage 23. The supply to the passage 23 and the chamber 22 in brake-applied position is maintained from the triple valve chamber 5. In the right-hand position of the valve 15, i.e. with the vehicle unloaded, an auxiliary brake cylinder connected to a pipe 17 is connected by a cavity 16 to an atmospheric outlet 18 and in the left-hand or loaded position this cylinder is connected to the brake cylinder supply passage 13, additional braking pressure for a loaded vehicle may thus be obtained. When the train pipe is charged above a certain pressure, train-pipe air passing through a passage 30 to a chamber 29 acts on the piston 26 to compress the spring 46 and move the arm 36 out of engagement with the spring box 37, the piston 26 uncovers a groove 33 to admit pressure fluid to the right of the larger piston 27 which is moved into engagement with a gasket 44 so as to cut the train pipe off from the atmosphere. The pipe 24 is thus blanked and the valve 15 retained in its position. On brake application the triple valve connects the train pipe to an accelerating bulb 54 and supplies the brake cylinder passage 13 by a graduated valve 8, passages 9, 10 and a restricted port 11, in unloaded position and also by a graduated port 12 in loaded position. The ball valve 40 isolates the auxiliary reservoir 6 from the train pipe when the train pipe is completely vented in which case the pistons 26, 27 will have returned to the position shown in Fig. 1 and the valve 40 will be subject on its upper side to the pressure in reservoir 6 through passage 23 and past the piston 14. In a modification a rotary plug cock effects the same action as the slide valve 15 and is connected to a piston in a cylinder controlled by the valve 28.