Speed converter with zero backlash

Apparatus for converting a rotary motion input to an output motion, comprising

• driven track means for driving an output,
• means for retaining an interacting element, said retaining means having at least one slot, and
• drive track means for driving said driven track means via at least one interacting element traveling in said retaining means slot,
• said drive track means and said driven track means comprising a conjugate pair of devices which cooperate together to define a straight path of travel of said element in said slot,
• each of said driven and driven track means having at least a rise side and at least a fall side,
• said rise sides forming a rise side pair and said fall sides forming a fall side pair, wherein said interacting element is in intimate contact with one member of each said pair simultaneously without contacting all members of all said pairs,
• preloading means for axially preloading said drive track means, said driven track means and said interacting element into said intimate contact, and
• all said means coaxially mounted along a common central axis, said driven track means having at least one cycle, said drive track means having at least one cam cycle for driving said driven track means via said at least one interacting element in said slot, all said means cooperating for converting rotary motion at said input at an input speed to an output speed at said output, said output speed being dictated according to the ratio of the number of said cycles of said drive track means and of said cycles of said driven track means, wherein said ratio is other than unity.