A toothed front side forced by {HEAD ~ the spring force} into {TAIL ~ engagement} with the ratchet wheel in the box end 
into
A toothed front side forced by { HEAD ~ the spring force } into { TAIL ~ engagement } with the ratchet wheel in the box end
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH