Abstract: The meshing gear teeth comprise cylindrical profile teeth on a gear or rack and circular arc profile teeth on the other gear or pinion. Each cylindrical profile tooth is preferably mounted for free rotation about the cylindrical axis of the tooth. Driving engagement of the gears rotates the contacting cylindrical teeth, thereby providing rolling contact between the meshing gear teeth. At any instant, at least two cylindrical teeth on one gear are in engagement with one tooth on the other gear. With the motion of the meshing gears, the cylindrical profile teeth rotate into and out of the roots of the other gear without loss of rolling contact from entrance to exit. The constant contact and multi tooth engagement prevents backlash relative movement between the gears.