{TAIL ~ The cam plates} are in contact with the cam surfaces, and serve for positioning {HEAD ~ the sliding frames} 
{ TAIL ~ The cam plates } are in contact with the cam surfaces , and serve for positioning { HEAD ~ the sliding frames }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD