GB1202312A - A shut-off device for driver's brake valves of compressed air brake installations on rail vehicles - Google Patents

Abstract

1,202,312. Railway braking systems. KNORR-BREMSE G.m.b.H. 13 Feb., 1968 [14 Feb., 1967], No. 6950/68. Heading F2F. A safety device for compressed-air railway braking systems comprises between the train pipe and the driver's valve a shut-off member which, when the brakes are applied, shuts off the driver's valve from the train pipe and vents the latter to the atmosphere so that a leak of pressure from the driver's valve cannot enter the train pipe and cause unintentional release of the brakes. In Fig. 1 the driver's valve 2 is isolated from the brake pipe 3 by a valve 4 operated by an auxiliary shut-off valve 18. In normal operation valve 18 allows compressed air from the train pipe 20 to flow through lines 19 and 17 to chamber 16, wherein piston 12 moves to the left to lift valve 7 off its double annular seat 8a, 8b. Thus a connection is established between the driver's valve 2 and the brake pipe 3 via chambers 6 and 9. When the driver's valve is closed, leaks therein, which could result in a rise of pressure in the brake pipe 3 and premature release of the brakes, are nullified by moving valve 18 to its other position. Line 17 is now vented to the atmosphere so that piston 12 is driven to the right by a spring 15, uncovering the end of the hollow valve stem 13, and venting this to the atmosphere via chamber 11. At the same time, the valve 7 seats on 8a, 8b isolating chamber 9 from conduit 5 and the driver's valve 2. The piston 12 may be moved manually by a direct connection. In an alternative form (Fig. 2) the auxiliary control 18 is replaced by a special position on the hand lever 1 in which the pressure in the regulator 21 is reduced to atmospheric. As before, a piston 36 then moves to the right allowing a valve 35 to close and isolate the brake pipe 3. Chamber 26 is also reduced to atmospheric pressure so that any pressure remaining in chambers 24 and 29 moves a piston 28 to the right. A valve tube attached to this piston is then unsealed from a valve plate 30 and chambers 24 and 29 are vented to the atmosphere via this valve tube. When the lever 1 is moved to its normal position pressure rises in line 25 and via pistons 28 and 36 forces both valves to the left, connecting chamber 29 to the pressure in regulator 21, and consequently connecting this to the brake pipe 3 via chamber 24. This arrangement with a relay valve 22 can also be used with a separate control 18 (Fig. 3, not shown). In another modification of Fig. 2 (Fig. 4, not shown) the driver's valve operates an impulse valve (40) which operates the relay valve 22 directly and the other valve 35 via a reservoir and non-return valve (41) to the other side of which the auxiliary control (44) is connected. This gives a quick-acting control, and may be used with the regulator 21 instead of an impulse valve.