WORM AND WORM GEAR SELECTION
Commonly Gear manufactures standard stock worms made from high quality steel (both hardened and unhardened). Depending on pitch, hardened worms are available with polished only threads as well as with ground and polished threads. Standard stock worm gears are available – depending on pitch – in fine grain cast iron and bronze.
Approximate input horsepower and output torque ratings for stock worm and worm gear combinations – ranging from 12 to 3 DP – are always illustrated in your Gears catalog.
The ratings shown for hardened, ground, and polished worms operating with bronze worm gears. For other combinations, multiply the listed ratings by the following percentages:
• Hardened, ground, and polished steel worms with cast iron gears: 50%
• Unhardened steel (.40 Carbon) worms with cast iron gears: 25%
Take note: These ratings are listed at selected worm speeds. Ratings for intermediate speeds may be estimated, or interpolated from the values indicated.
The ratings reflected on the chart should be satisfactory for gears:
1) operated under normal conditions,
2) properly mounted in accordance with good design practice, and
3) continuously lubricated with a sufficient supply of oil, carrying a smooth load (without shock) for 8 to 10 hours a day. These ratings were established using a mineral oil compounded with 3-10 percent of acid-less tallow. This is a recommended lubrication for worm and worm gear drives.
Important: Extreme Pressure (E.P.) lubricants are not recommended for use with bronze worm gears.
