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