The Advantage of Worm Drive Mixers

Sharpe E-Series Mixer Drive.

Worm gear drive mixers utilize a hardened and ground steel high speed worm shaft threading through a bronze slow speed worm gear.  The design allows the softer bronze worm gear to wear into the hardened shaft during the first few months of operation, providing a nearly silent operating gearbox.

Besides from the quiet operation, there are a number of other advantages associated with worm gears.  Shock loading that would break teeth on a helical or spiral-bevel gearbox merely deforms the bronze gear on a worm gearbox.  Once the overload passes, the hardened worm shaft wears back into the bronze gear and the reducer will continue to operate.  In fact, worm gears are known to withstand momentary peak overloading of 300% without failure.

The timing of required maintenance is better predicted with worm gears since it is easy to check the wear on the bronze gear by periodically measuring the backlash (turning the worm shaft back and forth to check the free play).

Worm gearboxes are also able to achieve higher ratios within a single reduction, up to 100:1 as compared to ~6:1 with conventional single stage helical gear reducers.  A helical or spiral-bevel gear reducer would require double or triple reduction to reach the required mixer speed, and therefore would have multiple sets of bearings and gears subject to wear and failure.  A comparable worm gearbox would have only one gear set and intermediate gears or bearings, and would be simpler to maintain and rebuild if the need should arise.

Worm gear reducers are right-angle gearboxes which results in a low profile agitator drive, an advantage when there is restricted headroom on a particular installation.

Worm gears are not as efficient as helical or spiral-bevel gear reducers, although low ratios like 5:1 or 7.5:1 are still above 90% efficiency.  As the ratio increases, the efficiency decreases.

More information can be found in our E-Series brochure.  Is a worm drive mixer right for you?  Contact us today and let us help you decide!