{HEAD ~ The control cam} and a contact surface of {TAIL ~ the feeler roller} are in operative rolling contact during at least part of a period repeating in the respective periods 
of
{ HEAD ~ The control cam } and a contact surface of { TAIL ~ the feeler roller } are in operative rolling contact during at least part of a period repeating in the respective periods
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH