GB112549A - Improvements in Brake Mechanism for Railway and like Vehicles. - Google Patents

Abstract

112,549. Gresham, S. T., and Gresham, J. M., (Executors of Gresham, F. J.), and Kiernan, G. March 22, 1917. Fluid-pressure.-The steam brakes of a locomotive are automatically actuated simultaneously with the actuation of the automatic pressure or vacuum brakes, by means of a piston subjected on one side to the train-pipe pressure and on the other side to the pressure in a reservoir. The steam-brake valve may be fitted with a pilot valve adapted to be opened first so as to balance the pressures on the main valve and facilitate its opening. Fig. 1 shows a piston e operating in a cylinder a connected at b to the train-pipe, and at c to a reservoir fed from the train-pipe through a groove d. When train-pipe pressure is reduced, the piston e is raised and by means of a lever g and plunger i, cuts off the steam-brake connexion k from the exhaust m and opens the steam valve h. Release is effected when the train-pipe pressure is raised again to the reservoir pressure, causing the piston e to descend. The lever g may be actuated by hand. Fig. 2 shows a modification having a valve r which facilitates the release by allowing the train-pipe and reservoir pressures to equalize as soon as the recharging of the trainpipe for release begins. When train-pipe pressure is reduced, a supplementary valve u opens to cause a corresponding reduction above the piston c; and when the train-pipe is recharged, the valve r is moved to the position shown, thereby opening the train-pipe to the cylinder a by means of a groove t, and to the reservoir by an annular groove s and port q. The steam valve h is fitted with a pilot valve v which is first opened, thereby admitting steam through a passage x to a chamber y so as to balance the pressures on the valve h. Fig. 3 shows the valve r formed with an enlarged part and with the annular groove s communicating with the interior of the valve, the supplementary valve u being positively opened by contact with the cylinder a. In another form, the annular groove is dispensed with, communication with the reservoir being provided by means of a lift valve actuated by a cam-recess in the valve r. Fig. 4 shows modified means for actuating the steam valve by hand; the lever g is engaged by an arm 10 actuated by a rod 11 to which movement is communicated from a hand-wheel 12 through a spring 13. Fig. 4 shows also a modified arrangement of pilot valve v. In the case of a vacuum brake, one side of the piston e communicates directly with the train-pipe, and the other side through a non-return valve, the latter side being also connected to the reservoir.