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