The second clamp 14 opens by removing a primary pin and a safety pin in {HEAD ~ the nature} of {TAIL ~ the first clamp} 
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The second clamp 14 opens by removing a primary pin and a safety pin in { HEAD ~ the nature } of { TAIL ~ the first clamp }
OTH OTH OTH 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 TAIL