Duplex Worm

Duplex Worm

Contrary to standard toothing of worm gear sets, the two flanks of duplex or dual lead worms and wheels are manufactured with slightly different modules and/or diameter quotients. As a result of this, different lead angles on both tooth profiles are obtained. With this the tooth thickness is continuously increasing all over the worm length, while the gap between two threads is decreasing.

At the worm wheel, the different modules result in different addendum modification coefficients and rolling circle diameters at both flanks. Because of this the profiles are different at the front and at the rear flank. The thickness of each tooth and the tooth gaps remain constant at the circumference of the wheel.

Backlash adjustment is done by shifting the worm axially, so that the section of the worm with the needed tooth thickness will be in contact with the wheel, giving the desired backlash (fig. 1).

This way, backlash can be easily adjusted to any desired value when mounting the gear, and even worn gears can be readjusted at any time delicately and continuously, without modifying the tooth contact or creating meshing interference.