GB605781A - Improvements in or relating to control devices for compressed air brake systems - Google Patents

Abstract

605,781. Fluid-pressure operated brakes. GALLUSSER, H. Dec. 28, 1944, No. 25981. Convention date, Feb. 21, 1944. [Class 103 (i)] A control valve device for automatic compressed-air brake systems comprises at least three units, each comprising an axially movable valve operating body connected to a casing by at least one flexible diaphragm which separates adjacent valve chambers, the main unit comprising four chambers connected respectively to brake cylinder, main control pipe, constant pressure chamber and atmosphere. An accelerator valve unit adapted to vent the control pipe chamber to a closed chamber, a unit for controlling the charging of the constant pressure chamber and auxiliary reservoir and a quick-inshot valve unit are included. The device shown comprises four units. The unit RV includes the brake cylinder supply and exhaust valves 45, 47 and comprises diaphragms 1 which with the valve body 4 and the casing define chambers 16, 17, 18, 19, connected respectively to atmosphere through passage c, a cock U and a restricted port 41, to a constant pressure chamber S by the chambers 12, 7, of units B, AV and pipe s, to the brake pipe H by chamber 13 and pipe h and to a chamber 20 by groove 52. Chamber 20 is connected to the brake cylinder BZ by pipe d and restricted port 54 in the " passenger-goods " change-over cock U and normally also by the quick-inshot valve unit M and pipe b. The unit M comprises a diaphragm 1 and body 5 subject to the opposing pressures of the spring 49 and the brake cylinder, so that valve 50 is normally held open. Chamber 20 and thus also the brake cylinder is normally open to atmosphere through the bore 40 and chamber 16. A brake pipe venting unit B comprises a body 3 and diaphragm 1 subject to opposing pressures in chambers 12, 13 connected respectively to the chamber S through chamber 7 and pipe s and to the brake pipe H. The venting chamber 14 is thus normally open to atmosphere through the bore 36. Spring bellows 34, 35 are connected to the valve spindle and to fixed parts. The unit AV controls the charging of the reservoir L and chamber S and comprises bodies 2, 2b, connected by diaphragms 1 to the casing. A chamber 9 connected to the brake pipe H by passage 25 is normally connected to the reservoir L by groove 30, chamber 8 restricted port 55 and passages 48, m and to chamber S by bore 27 with restriction 28, chamber 7 and pipe s. The brake pipe, reservoir and chamber S are thus normally interconnected. When to apply the brake, the brake pipe pressure is decreased rapidly enough to establish a pressure differential between the chambers 8, 9 and 7, the body 2 moves up to seat at 32 and to seat the valve 33,. thus cutting-off the chamber S and reservoir L from each other and the brake pipe. The brake pipe pressure reduction acting also in chamber 13 causes the spindle of body 3 to seat on the valve 37 and to lift valve 38, thus connecting the brake pipe H to the venting chamber 14. The brake pipe pressure reduction acting also in chamber 18 effects upward movement of the valve body 4, thus seating the valve 45 and lifting valve 47 whereby air is supplied from the reservoir L to the brake cylinder, at first both through passage d and cock U and also through passage 53, valve 50 and passage b. When the cylinder pressure acting in chamber 23 on the body 5 is sufficient to overcome the spring 49, the valve 50 closes and the cylinder is then supplied only through the restricted port 54 of the cock U. When the cylinder pressure acting in chambers 19, 20 on the diaphragm and valve body reaches a value corresponding to the pressure fall in chamber 18 the body 4 moves downwards sufficiently to reclose the valve 47. Release of the cylinder pressure can similarly be graduated by raising the brake pipe pressure. The' reservoir L is simultaneously charged through the non-return valve 26 but the valve body 2 is not moved downwardly to connect chamber S to the brake pipe and reservoir until the reservoir pressure has nearly reached the normal. If in charging the pressure in the pipe H and chamber 6 exceeds the normal, the' resultant upward force acting on the body 2b delays downward movement of the body 2 to open the valve 33 until the reservoir pressure has nearly reached and the pipe pressure has fallen to the normal value. Overcharging of the chamber S is thus prevented.