The third arm 48, via its lobe section 50, permits {HEAD ~ linear movement} in {TAIL ~ the directions} of the Y axis 
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The third arm 48 , via its lobe section 50 , permits { HEAD ~ linear movement } in { TAIL ~ the directions } of the Y axis
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH