A quick release valve for releasing the locomotive automatic brake independently of the train brakes when an AB/D type freight brake control valve is used on the locomotive. A release valve normally establishes a fluid control passage between the control valve and a relay valve that controls the locomotive brake pressure. When a quick release is made, the release valve is actuated to interrupt this fluid control passage and exhaust the relay valve portion of the passage to release the brakes. At the same time, a dissipation valve is effective to exhaust auxiliary reservoir pressure. If the quick release is made of a service application, the exhaust of auxiliary reservoir pressure will cause the control valve to exhaust the control valve portion of the control line and thereby prevent an automatic reapplication of the automatic brake following termination of the quick release function. The exhaust of control line pressure also causes the dissipation valve to reset to terminate further exhaust of auxiliary reservoir pressure, which is thus available in the event a further application of the automatic brake is desired. If the quick release is made of an emergency application, the exhaust of auxiliary reservoir pressure will have no influence on the control valve, since the brake pipe pressure will be completely exhausted, thus assuring a reapplication of the emergency brake following termination of the quick release operation.
A valve for use in a pneumatic fluid system, such as an air brake system, is disclosed. The valve provides for fast release of pneumatic fluid from the delivery cavity through the exhaust port upon cessation of flow from the pneumatic fluid reservoir through the supply cavity. The valve includes a flow diverter that restricts fluid flow from the delivery cavity to the supply cavity when pneumatic fluid pressure in the supply cavity is less than that in the delivery cavity with minimal restriction of flow from the supply cavity to the delivery cavity when pressure in the supply cavity is greater than in the delivery cavity.
