Brake Tests

77 continuous full service application without any emergency with this equipment (Fig. 41). Slightly higher cylinder pressure was obtained on most of the cars sufficient to operate the high-speed reducing valves so as to cause the characteristic blow-down of emergency brake cylinder pressure, but the rate of obtaining brake cylinder pressure is the same as if no emergency application had been made. 173. It required about the same time to reach this 60 pound brake cylinder pressure in this case as when no emergency application was made. 174. Moreover, it should be noted that the serial action of the valves remains the same. There was no serial quick action effect pro- duced by the emergency application following partial service application. The length of the stop, as would be expected, is but little different from that which was obtained with a full service application of the brakes, without any emergency application. UC Pneumatic Equipment. 175. In the case of the UC pneumatic equipment an emergency application produces serial quick action and full emergency brake cylin- der pressure, whether preceded by a service application or not, Fig. 46. Consequently, when the emergency application is made all the brakes applied simultaneously, the brake cylinder pressure rose at the usual emergency rate and the usual emergency maximum cylinder pressure was obtained. 176. From this it is plain that a very material increase in stopping power is possible by making an emergency application following a partial service application with the new complete pneumatic equip- ment. The result of this is to shorten the stop by about 300 feet com- pared with that obtained with a full service application, no emergency application being made. Electro-Pneumatic Equipment. 177. The action of the electro-pneumatic equipment (Fig. 47), simi- lar to that just described (Fig. 46), except that the time element due to the serial pneumatic application, both service and emergency, is elimi- nated, and the quicker rate of rise of brake cylinder pressure during the service application, which is due to the local venting of the air from the brake pipe on each car, produced by the electro-pneumatic service application feature. Both the service and the emergency appli- cations occur on all cars simultaneously and the brake cylinder pressure rises as promptly on each car of a twelve car train as it would on a single car. 178. A direct result of the quicker rate of brake pipe reduction is that the partial service reduction determined upon is completed sooner