| 摘要 |
<p>A hold-back valve for single release air brakes includes a plug valve member in a chamber of a valve body and rotatable between at least two positions to establish paths of different resistance to flow between air inlet and outlet passages in the valve body. The plug has spherical central portion with a flattened surface and the spherical central portion is sealingly engageable with one end of a hollow cylindrical flexible packing surrounding the opening of the air inlet passage to the chamber in the valve body. The rotatable plug has passages therethrough to define two or three different flow paths when particular passages of the plug are connected between the air inlet and outlet of the valve body.</p> |
