Here the two spring bars 5 and 6 are shown in the form of {HEAD ~ arms} pivotably attached to {TAIL ~ the portions} 2 and 4, and the known principle of parallelogram guidance is apparent 
Here the two spring bars 5 and 6 are shown in the form of { HEAD ~ arms } pivotably attached to { TAIL ~ the portions } 2 and 4 , and the known principle of parallelogram guidance is apparent
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH