Why Not to Use Worm Gears
There is one especially glaring reason one would not choose a worm gear more than a typical gear: lubrication. The movement between the worm and the wheel equipment faces is completely sliding. There is absolutely no rolling element of the tooth contact or interaction. This makes them fairly difficult to lubricate.
The lubricants required are usually very high viscosity 
(ISO 320 and greater) and therefore are tough to filter, and the lubricants required are typically specialized in what they perform, requiring something to be on-site particularly for that type of equipment.
Worm Gear Lubrication
The main problem with a worm gear is how it transfers power. It is a boon and a curse at the same time. The spiral motion allows huge amounts of reduction in a comparatively little bit of space for what’s required if a typical helical gear were used.
This spiral motion also causes an incredibly problematic condition to be the principal mode of power transfer. This is often called sliding friction or sliding wear.
With an average gear set the power is transferred at the peak load point on the tooth (referred to as the apex or pitchline), at least in a rolling wear condition. Sliding takes place on either part of the apex, but the velocity is relatively low.
With a worm gear, sliding motion is the only transfer of power. As the worm slides across the tooth of the wheel, it slowly rubs off the lubricant film, until there is absolutely no lubricant film still left, and for that reason, the worm rubs at the metallic of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface area, it picks up more lubricant, and starts the process over again on the next revolution.
The rolling friction on a typical gear tooth requires little in the form of lubricant film to fill in the spaces and separate the two components. Because sliding occurs on either part of the gear tooth apex, a slightly higher viscosity of lubricant than is usually strictly necessary for rolling wear is required to overcome that load. The sliding occurs at a comparatively low velocity.
The worm on a worm set gear turns, even though turning, it crushes against the load that’s imposed on the wheel. The only method to prevent the worm from touching the wheel is certainly to have a film thickness huge enough never to have the entire tooth surface wiped off before that part of the worm is out of the load zone.
This scenario requires a special sort of lubricant. Not only will it should be a comparatively high viscosity lubricant (and the bigger the strain or temperature, the higher the viscosity must be), it will need to have some way to greatly help get over the sliding condition present.
Read The Right Way to Lubricate Worm Gears for more information on this topic.
Custom Worm Gears
Worm Gears are correct angle drives providing huge velocity ratios on comparatively brief center distances from 1/4” to 11”. When correctly installed and lubricated they function as quietist and smoothest running type of gearing. Because of the high ratios possible with worm gearing, maximum speed reduction could be accomplished in less space than many other types of gearing. Worm and worm gears operate on nonintersecting shafts at 90° angles.
EFFICIENCY of worm gear drives depends to a large degree on the helix angle of the worm. Multiple thread worms and gears with higher helix angle prove 25% to 50% more efficient than one thread worms. The mesh or engagement of worms with worm gears produces a sliding action leading to considerable friction and higher loss of efficiency beyond other types of gearing. The usage of hardened and ground worm swith bronze worm gears raises efficiency.
LUBRICATION can be an essential factor to boost efficiency in worm gearing. Worm equipment action generates considerable warmth, decreasing efficiency. The amount of power transmitted at confirmed temperature improves as the performance of the gearing raises. Proper lubrication enhances efficiency by reducing friction and warmth.
RATIOS of worm gear sets are determined by dividing the amount of teeth in the gear by the number of threads. Thus solitary threads yield higher ratios than multiple threads. All Ever-Power. worm gear models can be found with either left or right hands threads. Ever-Power. worm equipment sets can be found with Single, Dual, Triple and Qua-druple Threads.
Basic safety PROVISION: Worm gearing should not be used because a locking mechanism to hold large weights where reversing actions can cause harm or injury. In applications where potential damage is nonexistent and self-locking is preferred against backward rotation after that use of a single thread worm with a low helix angle immediately locks the worm equipment drive against backward rotation.
Materials recommended for worms can be hardened steel and bronze for worm gears. Nevertheless, depending on the application form unhardened steel worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. In addition to metal and hardenedsteel, worms are available in stainless, aluminium, bronze and nylon; worm gears are available in steel, hardened metal, stainless, light weight aluminum, nylon and nonmetallic (phenolic).
worm drive shaft Ever-Power also sells equipment tooth measuring devices called Ever-Power! Gear Gages reduce mistakes, save time and money when identifying and buying gears. These pitch templates can be found in nine sets to recognize all the standard pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, Exterior Involute Splines, Metric Module “MOD”, Stub Tooth, Great Pitches, Coarse Pitches and Uncommon Pitches. Make reference to the section on Equipment GAGES for catalog quantities when ordering.