| 摘要 |
A pressure-relief valve device, especially for use with hydraulic props, has a main hollow housing containing a guide piece with a through bore in which a cylindrical shank of a valve or piston member is received. The shank is slidable within the guide piece bore and is held, by a spring force applied to a head thereof, in a closed position. The shank has a blind axial bore leading through five, or preferably six radial borings to outlets at is periphery. An O-ring held in a groove in the wall of the guide piece bore engages on the peripheral surface of the shank. An elastic deformable thrust disc is located in the groove and contacts a wall of the groove adjacent the head of the valve member as well as the O-ring. The thrust disc serves to prevent creep of the O-ring during use whereby excess fluid pressure acts to displace the valve member against the restoring force of the spring to move the outlets of the shank of the valve member passed the O-ring to allow pressure-relief. |
