The connecting block 3 is associated with vertical guide rails on {HEAD ~ the front} of {TAIL ~ the main body} 1 so that it can be moved up and down 
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The connecting block 3 is associated with vertical guide rails on { HEAD ~ the front } of { TAIL ~ the main body } 1 so that it can be moved up and down
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH