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