The engagement of the spring and {HEAD ~ the stop} with {TAIL ~ the drive lever} yields lever arms of different lengths 
with
The engagement of the spring and { HEAD ~ the stop } with { TAIL ~ the drive lever } yields lever arms of different lengths
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