Why Not to Use Worm Gears
There is one particularly glaring reason why one would not choose a worm gear more than a standard gear: lubrication. The motion between the worm and the wheel gear faces is entirely sliding. There is no rolling element of the tooth contact or conversation. This makes them fairly difficult to lubricate.
The lubricants required are usually very high worm drive shaft viscosity (ISO 320 and better) and thus are hard to filter, and the lubricants required are usually specialized in what they perform, requiring a product to be on-site specifically for that type of equipment.
Worm Gear Lubrication
The primary problem with a worm gear is how it transfers power. It is a boon and a curse simultaneously. The spiral movement allows huge amounts of reduction in a comparatively small amount of space for what is required if a standard helical equipment were used.
This spiral motion also causes an incredibly problematic condition to be the primary mode of power transfer. This is often called sliding friction or sliding put on.
With a typical gear set the power is transferred at the peak load stage on the tooth (referred to as the apex or pitchline), at least in a rolling wear condition. Sliding takes place on either aspect of the apex, but the velocity is fairly low.
With a worm gear, sliding motion may be the only transfer of power. As the worm slides over the tooth of the wheel, it gradually rubs off the lubricant film, until there is no lubricant film left, and for that reason, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface area, it accumulates more lubricant, and starts the procedure over again on another revolution.
The rolling friction on an average gear tooth requires small in the form of lubricant film to complete the spaces and separate the two components. Because sliding happens on either part of the gear tooth apex, a slightly higher viscosity of lubricant than is usually strictly necessary for rolling wear must overcome that load. The sliding takes place at a comparatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the load that is imposed on the wheel. The only method to avoid the worm from touching the wheel is definitely to get a film thickness huge enough never to have the whole tooth surface area wiped off before that section of the worm has gone out of the load zone.
This scenario requires a special sort of lubricant. Not just will it will have to be a comparatively high viscosity lubricant (and the higher the strain or temperature, the higher the viscosity should be), it must have some way to greatly help get over the sliding condition present.
Read The Right Method to Lubricate Worm Gears for more information on this topic.
Custom Worm Gears
Worm Gears are correct angle drives providing large swiftness ratios on comparatively brief center distances from 1/4” to 11”. When properly mounted and lubricated they function as the quietist and smoothest operating type of gearing. Due to the high ratios feasible with worm gearing, maximum speed reduction can be accomplished in much less space than a great many other types of gearing. Worm and worm gears operate on non-intersecting shafts at 90° angles.
EFFICIENCY of worm equipment drives depends to a sizable extent on the helix angle of the worm. Multiple thread worms and gears with higher helix angle prove 25% to 50% better than one thread worms. The mesh or engagement of worms with worm gears creates a sliding action leading to considerable friction and better lack of efficiency beyond other styles of gearing. The usage of hardened and ground worm swith bronze worm gears boosts efficiency.
LUBRICATION can be an essential factor to boost performance in worm gearing. Worm equipment action generates considerable temperature, decreasing efficiency. The amount of power transmitted at confirmed temperature raises as the efficiency of the gearing improves. Proper lubrication enhances effectiveness by reducing friction and heat.
RATIOS of worm equipment sets are dependant on dividing the amount of teeth in the gear by the amount of threads. Thus one threads yield higher ratios than multiple threads. All Ever-Power. worm gear models can be found with either left or right hand threads. Ever-Power. worm gear sets are offered with Single, Double, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing should not be used since a locking mechanism to hold large weights where reversing actions could cause harm or injury. In applications where potential damage is non-existent and self-locking is desired against backward rotation then use of a single thread worm with a low helix angle instantly locks the worm equipment drive against backward rotation.
Materials recommended for worms is usually hardened steel and bronze for worm gears. However, depending on the application form unhardened metal worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. Furthermore to steel and hardenedsteel, worms are available in stainless, aluminum, bronze and nylon; worm gears are available in steel, hardened metal, stainless, light weight aluminum, nylon and nonmetallic (phenolic).
Ever-Power also sells gear tooth measuring devices called Ever-Power! Gear Gages reduce mistakes, save time and money when identifying and ordering gears. These pitch templates can be found in nine sets to recognize all the regular pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, External Involute Splines, Metric Module “MOD”, Stub Tooth, Great Pitches, Coarse Pitches and Uncommon Pitches. Make reference to the section on GEAR GAGES for catalog numbers when ordering.