Worm Gear

Worm gear or “worm gears” are right angle drives which provide large speed ratios on comparatively short center distances from ¼”-11”. Most professionals would agree that when installed properly – meaning, properly mounted and lubricated, worm gears are the smoothest running type of gearing, and the quietest.

According to Rushgears.com, “efficiency of worm gear drives depends to a large extent on the helix angle of the worm. Multiple threadworms and gears with higher helix angle prove 25% to 50% more efficient than single threadworms. The mesh or engagement of worms with worm gears produces a sliding action causing considerable friction and greater loss of efficiency beyond other types of gearing. The use of hardened and ground worms with bronze worm gears increases efficiency.”

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Rushgears.com also discusses lubrication, material, ratios, and safety provisions. Please continue reading to find out more about worm gears.

Lubrication is an essential factor to improve efficiency in worm gearing. Worm gear action generates considerable heat, decreasing efficiency. The amount of power transmitted at a given temperature increases as the efficiency of the gearing increases. Proper lubrication enhances efficiency by reducing friction and heat.

Material recommended for worms is hardened steel and bronze for worm gears. However, depending on the application unhardened steel worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. In addition to steel and hardened steel, worms are available in stainless, aluminum, bronze and nylon; worm gears are available in steel, hardened steel, stainless, aluminum, nylon and non-metallic (phenolic).

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Ratios of worm gear sets are determined by dividing the number of teeth in the gear by the number of threads. Thus single threads yield higher ratios than multiple threads. Seek out manufacturers that offer worm gears with either left or right hand threads and worm gear sets with Single, Double, Triple and Qua-druple Threads.

Safety Provisions
Worm gearing should not be used as a locking mechanism to hold heavy weights where reversing action can cause harm or injury. In applications where potential harm is non-existent and self-locking is desired against backward rotation then use of a single threadworm with a low helix angle automatically locks the worm gear drive against backward rotation.

Works Cited

Rush Gears. 14 Jan. 2009. .

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