A point on the contact surface of the feeler roller which coincides with a first contact point in a first operational setting of the second transmission linkage coincides at least approximately with {HEAD ~ a second contact point} in {TAIL ~ a second operational setting} of the second transmission linkage 
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A point on the contact surface of the feeler roller which coincides with a first contact point in a first operational setting of the second transmission linkage coincides at least approximately with { HEAD ~ a second contact point } in { TAIL ~ a second operational setting } of the second transmission linkage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH