Hourglass worm 1 rotates about fixed axis A-A and its threads b mesh with cylindrical pins a of pin-wheel 2 which rotates about fixed axis B. Pins a are designed as rollers located on the outside cylindrical surface of wheel 2 and can turn about their axes d, thereby substantially reducing friction losses in the gearing. The transmission ratio of the mechanism is i₁₂=ω₁/ω₂=z₂/z₁ where ω₁ and ω₂ are the angular velocities of worm 1 and wheel 2, z₁ is the number of threads, or starts, of worm 1 and z₂ is the number of pins on wheel 2.
$2809$WG,3L$