The spring force is coupled to {HEAD ~ the test member} via a movable member which moves in {TAIL ~ a substantially frictionless manner} 
The spring force is coupled to { HEAD ~ the test member } via a movable member which moves in { TAIL ~ a substantially frictionless manner }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL