Brake Tests

64 (c) Cut off the safety valve from its connection to the brake cylinder. (d) As soon as service and auxiliary reservoirs equalize with the brake cylinder the intercepting valve and service port check valve operate to cut off the service and the auxiliary reservoirs from the brake cylinder and at the same time admit air from the emergency reservoir to the brake cylinder, thus continuing the building up of the brake cylinder pressure to its maximum emergency value. (e) After the quick action valve has been open for a sufficient length of time to insure the necessary reduction in brake pipe pressure to propagate serial quick action it is allowed to close by the depletion of the quick action closing chamber pressure, which is properly timed to produce the desired result by the size of the port through the quick action piston. EMERGENCY BRAKE APPLICATION AFTER SERVICE BRAKE Application. 129. Whenever a predetermined emergency rate of brake pipe reduction is established the quick action and high pressure parts of the valve will operate as above described to start serial quick action and increase the brake cylinder pressure up to its full emergency value even though a partial or full service brake application had been com- pleted or was in progress. That is to say, the obtaining of an emer- gency application of the brakes depends only on the functioning of the quick action parts and is entirely independent of the service oper- ation of the valve. Emergency Brake Application Automatic on Depletion of BRAKE Pipe Pressure BELOW a Predetermined Point. 130. Whenever, from any cause, the brake pipe pressure is reduced to a predetermined value (30 pounds), the protection valve included in the emergency portion of the universal valve will operate and cause the parts of the emergency portion to move to their quick action positions and so start a quick action application of the brakes—the operation of the equipment then being as already explained. (Par. 128.) 131. Within certain limits the percentage of emergency braking power and the brake pipe pressure to be used may be chosen as the con- ditions of operation and installation may dictate without requiring a change in any essential part of the apparatus and without affecting the fundamental and proper relations between the different reservoirs, cyl- inders and operating parts of the equipment. For example, one or two brake cylinders per car may be used as the weight of the car and the percentage of braking power desired may require, the only change neces- sary being the use of a special cap on the high pressure portion of the valve designed to handle two brake cylinders instead of one. The amount of emergency braking power can be fixed to suit special limits or requirements by proper choice of reservoir volumes and (when