The support arms are pivotally attached through rotary shafts, which are individually mounted at opposite ends of {HEAD ~ each} of {TAIL ~ the support arms} 
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The support arms are pivotally attached through rotary shafts , which are individually mounted at opposite ends of { HEAD ~ each } of { TAIL ~ the support arms }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL