Abstract: A rotary-to-linear converter for use with a valve actuation device having a linear reciprocating cam shaft having longitudinally extending cam grooves that are engaged by captive cam followers which oscillate up and down in response to sideways reciprocation of the camshaft for actuating intake or exhaust valves of internal combustion engines or other devices employing reciprocating pistons and valves. The camshaft is caused to reciprocate by a rotary linear converter of the “yankee” type composed of double helix channel at the extreme end of the camshaft and a rotary drive collar having two sets of diametrically opposed guide members. The guide members comprise dogs which are rotatably engaged with the drive collar and slidably engaged with the double helix channel of the cam shaft.