This disclosure relates to drive apparatus including a rotatable member and a relatively fixed or non rotatable member. The two members are coupled by a thread type arrangement whereby one of the two members is moved linearly relative to the other when the rotatable member is rotated. The rotatable member includes a cylinder and a plurality of rollers attached to the outer periphery of the cylinder. The rollers are arranged in a helical line and extend radially outwardly from the cylinder. The fixed member includes a semicylindrical wall having a plurality of slots or channels formed in it, the channels also following a helical line that is similar to the line followed by the rollers. When the rotatable member is turned on its axis, the rollers move through the channels and cause relative linear movement of the two members.