Why Not to Use Worm Gears
There is one particularly glaring reason why one would not select a worm gear over a typical gear: lubrication. The motion between your worm and the wheel equipment faces is completely sliding. There is no rolling element of the tooth get in touch with or conversation. This makes them relatively difficult to lubricate.
The lubricants required are often high viscosity (ISO 320 and better) and thus are challenging to filter, and the lubricants required are usually specialized in what they perform, requiring something to be on-site specifically 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 is required if a standard helical gear were used.
This spiral motion also causes an incredibly problematic condition to be the primary mode of power transfer. This is often called worm drive shaft sliding friction or sliding wear.
With an average gear set the energy is transferred at the peak load point on the tooth (known as the apex or pitchline), at least in a rolling wear condition. Sliding takes place on either side 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 across the tooth of the wheel, it slowly rubs off the lubricant film, until there is no lubricant film still left, and as a result, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface area leaves the wheel surface, it picks up more lubricant, and starts the process over again on the next revolution.
The rolling friction on an average gear tooth requires little in the way of lubricant film to fill in the spaces and separate both components. Because sliding happens on either side of the gear tooth apex, a somewhat higher viscosity of lubricant than can be strictly necessary for rolling wear must 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 strain that’s imposed on the wheel. The only way to prevent the worm from touching the wheel is certainly to get a film thickness large enough never to have the whole tooth surface wiped off before that portion of the worm has gone out of the strain zone.
This scenario takes a special sort of lubricant. Not just will it will have to be a relatively high viscosity lubricant (and the bigger the load 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 Method to Lubricate Worm Gears to learn more on this topic.
Custom Worm Gears
Worm Gears are right angle drives providing large quickness ratios on comparatively brief center distances from 1/4” to 11”. When correctly mounted and lubricated they function as quietist and smoothest operating type of gearing. Due to the high ratios feasible with worm gearing, optimum speed reduction could be accomplished in less space than many other types of gearing. Worm and worm gears are powered by nonintersecting shafts at 90° angles.
EFFICIENCY of worm gear drives depends to a huge extent on the helix position of the worm. Multiple thread worms and gears with higher helix angle prove 25% to 50% better than single thread worms. The mesh or engagement of worms with worm gears generates a sliding action leading to considerable friction and higher lack of efficiency beyond other styles of gearing. The use of hardened and surface worm swith bronze worm gears improves efficiency.
LUBRICATION is an essential factor to improve efficiency in worm gearing. Worm equipment action generates considerable high temperature, decreasing efficiency. The amount of power transmitted at a given temperature increases as the performance of the gearing boosts. Proper lubrication enhances efficiency by reducing friction and heat.
RATIOS of worm equipment sets are dependant on dividing the number of teeth in the gear by the number of threads. Thus one threads yield higher ratios than multiple threads. All Ever-Power. worm gear pieces can be found with either still left or right hands threads. Ever-Power. worm equipment sets can be found with Single, Dual, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing shouldn’t be used because a locking mechanism to carry 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 after that use of an individual thread worm with a low helix angle immediately locks the worm equipment drive against backward rotation.
Materials recommended for worms is hardened steel and bronze for worm gears. Nevertheless, 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, aluminium, bronze and nylon; worm gears are available in steel, hardened steel, stainless, aluminum, nylon and nonmetallic (phenolic).
Ever-Power also sells equipment tooth measuring devices called Ever-Power! Gear Gages decrease mistakes, save money and time when identifying and buying gears. These pitch templates are available in nine sets to recognize all the standard pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, External Involute Splines, Metric Module “MOD”, Stub Tooth, Fine Pitches, Coarse Pitches and Unusual Pitches. Refer to the section on Equipment GAGES for catalog quantities when ordering.
Why Not to Use Worm Gears