A mechanism for controlling {HEAD ~ the position} of a movable member and for locking it in {TAIL ~ any desired position} comprising a hydraulic displacement device movable with the member and a slide valve hydraulically connected to the displacement device to control flow of liquid to or from the device 
A mechanism for controlling { HEAD ~ the position } of a movable member and for locking it in { TAIL ~ any desired position } comprising a hydraulic displacement device movable with the member and a slide valve hydraulically connected to the displacement device to control flow of liquid to or from the device
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH