Why Not to Use Worm Gears
There is one particularly glaring reason one would not select a worm gear more than a typical gear: lubrication. The motion between your worm and the wheel gear faces is entirely 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 higher) and therefore are challenging to filter, and the lubricants required are usually 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 really is a boon and a curse at the same time. The spiral movement allows huge amounts of reduction in a comparatively little bit of space for what’s 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 commonly known as sliding friction or sliding wear.
With an average 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 side 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 over the tooth of the wheel, it gradually rubs off the lubricant film, until there is absolutely no lubricant film remaining, and as a result, the worm rubs at the metal 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 procedure 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 both components. Because sliding takes place on either side of the apparatus tooth apex, a slightly higher viscosity of lubricant than is certainly strictly needed for rolling wear must overcome that load. The sliding occurs at a relatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the strain that is imposed on the wheel. The only method to prevent the worm from touching the wheel can be to possess a film thickness huge enough never to have the entire tooth surface wiped off before that portion of the worm has gone out of the strain zone.
This scenario requires a special kind of lubricant. Not just will it should be a relatively high viscosity lubricant (and the bigger the strain or temperature, the bigger the viscosity should be), it must have some way to greatly help conquer the sliding condition present.
Read The Right Method to Lubricate Worm Gears to find out more on this topic.
Custom Worm Gears
Worm Gears are right angle drives providing large rate 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 possible with worm gearing, optimum speed reduction can be accomplished in 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 big degree on the helix position of the worm. Multiple thread worms and gears with higher helix position prove 25% to 50% more efficient than solitary thread worms. The mesh or engagement of worms with worm gears produces a sliding action causing considerable friction and higher lack of efficiency beyond other types of gearing. The utilization of hardened and surface worm swith bronze worm gears boosts efficiency.
LUBRICATION is an essential factor to improve performance in worm gearing. Worm gear action generates considerable temperature, decreasing efficiency. The amount of power transmitted at confirmed worm drive shaft temperature boosts as the performance of the gearing boosts. Proper lubrication enhances performance by reducing friction and high temperature.
RATIOS of worm equipment sets are determined by dividing the number of teeth in the apparatus by the amount of threads. Thus one threads yield higher ratios than multiple threads. All Ever-Power. worm gear sets can be found with either remaining or right hand threads. Ever-Power. worm gear sets can be found with Single, Dual, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing should not be used as a locking mechanism to carry weighty weights where reversing actions could cause harm or damage. In applications where potential harm is nonexistent and self-locking is preferred 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 definitely 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 can be found in stainless, light weight aluminum, bronze and nylon; worm gears can be found in steel, hardened metal, stainless, light weight aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells equipment tooth measuring gadgets called Ever-Power! Gear Gages reduce mistakes, save time and money when identifying and buying gears. These pitch templates are available in nine sets to identify all the regular pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, External Involute Splines, Metric Module “MOD”, Stub Tooth, Great Pitches, Coarse Pitches and Unusual Pitches. Make reference to the section on Equipment GAGES for catalog amounts when ordering.
worm drive shaft
Why Not to Use Worm Gears