| 摘要 |
The device includes a coiled extension spring, one end containing a hook for pivotal attachment either to the door or door frame, the other end being open to receive an elongated, tubular guide, one end of which threads into the open end of the spring. The other end of the guide is closed and contains a coaxial aperture through which slides an elongated rod having one end adapted for pivotal attachment to the other of the door or door frame and a piston attached to its second end which is slidably-retained within the guide to position the rod during relative coaxial sliding of the rod and guide, and to stop the rod against further protractive movement when the piston abuts the closed end of the guide. Camming surfaces located radially on the piston cooperate with opposing follower means in the guide, of which two embodiments are disclosed, to clamp the piston in the most extensive position of the rod, which clamping action can be overcome by a retractive force of the rod of a predetermined amount. When in the fully-protracted position, the device is capable of absorbing large amounts of shock, such as would be caused by collisions by heavy objects against the door.
|
