| 摘要 |
<p>The control comprise a cylindrical coupling, having an upper section containing an axial bore and a lower section containing a threaded axial bore. The lower section having a bottom cam surface. There is an upper rod, containing an annular groove at its lowermost end, which is rigidly affixed within the axial bore in the upper section of the coupling; and a lower rod, having an externally threaded upper portion which is affixed within the threaded axial bore of the lower section of the coupling. There is a locking member having an upper cam surface for engaging the cam surface of the coupling a first spring for biasing the coupling against the locking member, and a second spring for biasing the locking member against the coupling. When the coupling is shifted toward the first spring and out of engagement with the locking member, the coupling may be rotated to shift the lower rod to a different position relative to the upper rod.</p> |
