| 摘要 |
A freight brake control valve device in which the emergency piston slide valve is arranged to incorporate, in conjunction with the conventional service stability function provided thereby, an accelerated service application function in which a continuous local venting of brake pipe pressure is provided to hasten propagation of service rates of brake pipe reduction. A preliminary flow restrictor in one flow path and a primary flow restrictor in a parallel flow path control the quick-action chamber "breathing" rate such that the emergency piston is stabilized against movement to emergency position, as long as the brake pipe pressure reduction does not exceed a service rate. Following a service application, the preliminary flow restrictor has the further function of maintaining "breathing" until after the local reduction of brake pipe pressure is cut off, thereby assuring positive movement of the emergency piston to its service lap position. |
