Why Not to Use Worm Gears
There is one especially glaring reason why one would not choose a worm gear over a standard gear: lubrication. The movement between the worm and the wheel gear faces is completely sliding. There is absolutely no rolling element of the tooth get in touch with or conversation. This makes them fairly difficult to lubricate.
The lubricants required are usually very high viscosity (ISO 320 and better) and therefore are tough to filter, and the lubricants required are typically specialized in what they do, requiring something to be on-site particularly for that kind of equipment.
Worm Gear Lubrication
The primary problem with a worm gear is how it transfers power. It is a boon and a curse at the same time. The spiral movement allows large sums of reduction in a comparatively little bit of space for what is required if a typical helical gear were used.
This spiral motion also causes an incredibly problematic condition to be the primary mode of power transfer. That is commonly known as sliding friction or sliding wear.
With a typical gear set the power is transferred at the peak load stage on the tooth (known 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 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 gradually rubs off the lubricant film, until there is absolutely no lubricant film remaining, and for that reason, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface area leaves the wheel surface area, it picks up more lubricant, and starts the procedure over again on the next revolution.
The rolling friction on a typical gear tooth requires small in the way of lubricant film to complete the spaces and separate the two components. Because sliding occurs on either aspect of the apparatus tooth apex, a somewhat higher viscosity of lubricant than is definitely 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, and while turning, it crushes against the load that is imposed on the wheel. The only way to prevent the worm from touching the wheel can be to have a film thickness large enough to not have the entire tooth surface wiped off before that portion of the worm is out of the strain zone.
This scenario takes a special kind of lubricant. Not only will it will have to be a comparatively high viscosity lubricant (and the bigger the strain or temperature, the bigger the viscosity should be), it will need to have some way to help conquer the sliding condition present.
Read The Right Way to Lubricate Worm Gears to find out more on this topic.
Custom Worm Gears
Worm Gears are right angle drives providing huge swiftness ratios on comparatively brief center distances from 1/4” to 11”. When correctly mounted and lubricated they function as the worm drive shaft quietist and smoothest running type of gearing. Because of the high ratios feasible with worm gearing, optimum 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 degree on the helix angle of the worm. Multiple thread worms and gears with higher helix position prove 25% to 50% more efficient than single thread worms. The mesh or engagement of worms with worm gears creates a sliding action causing considerable friction and better lack of efficiency beyond other styles of gearing. The use of hardened and floor worm swith bronze worm gears improves efficiency.
LUBRICATION can be an essential factor to improve efficiency in worm gearing. Worm gear action generates considerable high temperature, decreasing efficiency. The amount of power transmitted at a given temperature increases as the effectiveness of the gearing boosts. Proper lubrication enhances performance by reducing friction and warmth.
RATIOS of worm gear sets are determined by dividing the amount of teeth in the apparatus by the number of threads. Thus single threads yield higher ratios than multiple threads. All Ever-Power. worm gear pieces are available with either remaining or right hands threads. Ever-Power. worm gear sets can be found with Single, Double, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing should not be used as a locking mechanism to carry large weights where reversing actions could cause harm or damage. 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 immediately locks the worm equipment drive against backward rotation.
MATERIAL recommended for worms is certainly hardened steel and bronze for worm gears. However, depending on the application unhardened metal worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. In addition to steel and hardenedsteel, worms are available in stainless, light weight aluminum, bronze and nylon; worm gears are available in steel, hardened metal, stainless, light weight aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells gear tooth measuring products called Ever-Power! Gear Gages reduce mistakes, save money and time when identifying and ordering 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, Fine Pitches, Coarse Pitches and Unusual Pitches. Refer to the section on GEAR GAGES for catalog amounts when ordering.
Why Not to Use Worm Gears