Full Service Application

Corresponds to a handle position for the automatic brake handle. In this position the brake pipe should be at 62 PSI (down from a 90 PSI release charge pressure). When an application is made on the automatic brakes, the equalizing reservoir pressure drops in proportion to the handle movement. The self lapping valve (Automatic Brake Valve ) then vents brake pipe pressure at a service rate until the equalizing reservoir and brake pipe pressures are equal. This pressure is measured on the locomotive only. It may be less further back on the train due to leakage. A minimum reduction is a 6 PSI drop to 84 PSI. After a minimum reduction is made, the automatic brake valve handle is linear down to zero. If the locomotive has a direction on the reverser handle, or the independent brakes are released, below 45 PSI BPP an emergency will occur and a valve will blow the brake pipe to zero in a hurry (corrected by Bob Murphy).