Brake Tests

63 (a) Momentarily connect the auxiliary reservoir side of the equalizing piston to the atmosphere, thus insuring a positive movement of the equalizing parts of the valve to their release positions. (b) Operate the release piston and its valves so as to close this connection to the atmosphere and open the brake cylinder to the atmosphere, thus releasing the brakes. (c) Connect the emergency reservoir to the auxiliary reservoir and later to the service reservoir, thus recharging the system as already explained under the heading “Charging and Recharging.“ (Par. 117.) (J) After having moved to release position the equalizing parts remain in this position, and the brakes are fully released if the brake pipe pressure is continuously increased up to its normal running pressure. This will be the case if the graduated release cap is in direct release position even if the brake pipe pressure is increased in a series of steps or gradua- tions instead of continuously. (e) With the graduated release cap in graduated release position, if the brake pipe pressure is only partly restored (brake valve handle then being returned to lap position) the air flowing from the emergency reservoir in to the auxiliary reservoir tends to increase the pressure in the latter reservoir above that in the brake pipe. As soon as this occurs, the equalizing portion of the valve will operate so as to stop the exhaust of air from the brake cylinder, thus graduating the release of the brake and at the same time cutting off the flow of air from the emergency reservoir to the auxiliary reservoir, this graduated release operation can be repeated as may be desired, depending upon the amount of the preceding brake pipe reduction. When the auxiliary reservoir pressure has been increased to within about five pounds of the emergency reservoir pressure the service reservoir charging valve operates and connects the emergency reservoir to the service reservoir, thus permitting these two reservoirs to equalize and charge up to brake pipe pressure through the emergency reservoir charging port. After this no further graduation of the release is possible, but at the same time the brake cylinder pressure is then so low that any further graduation of the release is uncalled for. Emergency Brake Application with System Fully Charged. 128. In response to a rate of brake pipe reduction considerably more rapid than that established for the service operation of the brakes, the quick action parts of the valve operate so as to:— (a) Vent air from the brake pipe through a relatively large open- ing past the quick action valve to the atmosphere, thus producing the local venting of brake pipe air necessary to the rapid pneumatic propagation of serial quick action. (b) Open a large port leading from the auxiliary and service reser- voirs past the intercepting valve and high pressure valve of the emer- gency portion of the universal valve and into the brake cylinder.