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