Brake Tests

66 Electric Emergency from Engineer’s Brake Valve. 135. When an electric emergency application is made (the electric and pneumatic positions of the brake valve handle are the same) the emergency magnets on all cars are simultaneously and instantaneously energized. These magnets open their respective emergency magnet valves which in turn cause the quick action parts of each universal valve to operate and produce an emergency application of the brakes as previously described for the pneumatic portion of the equipment. (Par. 128.) Automatic EleCTRIC Emergency. 136. In case a hose bursts or a conductor’s valve is opened, the first universal valve to be affected by the resulting drop in brake pipe pressure will operate pneumatically. 137. In so doing its emergency switch is closed which then ener- gizes the emergency magnet circuit throughout the train, thus causing an electric emergency application on the rest of the cars as described. 138. The service and emergency magnets may be cut out if necessary by placing the magnet cut-out cap on the electric portion of the universal valve in the proper position. Partial Pneumatic Equipment. Equivalent of the PM Brake Equipment. 139. This arrangement of the pneumatic brake equipment was given a trial, merely to show that the type UC brake equipment could be applied to cars in a form which would duplicate the essential features of the PM equipment and so introduce no new operating features during a transition period. 140. In its partial form (PM features only) the equipment com- prises only the equalizing portion of the universal valve with the auxiliary and the service reservoirs as used with the complete device. The service and auxiliary reservoirs perform the same functions as already described. (Par. 120.) 141. In each service operation the mechanism functionates in the same manner as with the complete pneumatic equipment. That is to say, the service application, release and recharging of the equipment is identical for the partial and for the complete pneumatic equipment. 142. In emergency applications, only the auxiliary and the service reservoirs supply air to the brake cylinder so that the rate of rise of brake cylinder pressure is slower than with a complete pneumatic equipment and a lower maximum brake cylinder pressure is obtained (78 pounds instead of 100 pounds). 143. As the high pressure portion is not used, the protection which the safety valve of the high pressure portion offers against too high a cylinder pressure on service applications is secured by the use of an ordinary high-speed reducing valve attached in the usual way to the brake cylinder. In this respect the action of the UC equipment, PM features only, and the present standard PM equipment are identical, both having the disadvantage of blowing away some of the air in the emergency application.