Why Not to Use Worm Gears
There is one particularly glaring reason why one would not select a worm gear over a standard gear: lubrication. The movement between the worm and the wheel gear faces is entirely sliding. There is absolutely no rolling component to the tooth get in touch with or conversation. This makes them relatively difficult to lubricate.
The lubricants worm drive shaft required are usually high viscosity (ISO 320 and higher) and thus are hard to filter, and the lubricants required are usually specialized in what they do, 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 really is a boon and a curse simultaneously. The spiral movement allows large sums of decrease 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. This is commonly known as sliding friction or sliding use.
With an average gear set the energy 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 occurs 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 slowly rubs off the lubricant film, until there is no lubricant film remaining, and for that reason, the worm rubs at the metallic 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 another revolution.
The rolling friction on an average gear tooth requires small in the form of lubricant film to fill in the spaces and separate the two components. Because sliding happens on either aspect of the gear tooth apex, a slightly higher viscosity of lubricant than is definitely strictly necessary for rolling wear must overcome that load. The sliding happens at a comparatively low velocity.
The worm on a worm set gear turns, and while 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 possess a film thickness large enough never to have the whole tooth surface area wiped off before that area of the worm is out of the load zone.
This scenario takes a special kind of lubricant. Not only will it should be a relatively high viscosity lubricant (and the bigger the load or temperature, the higher the viscosity should be), it will need to have some way to greatly help conquer the sliding condition present.
Read The Right Method to Lubricate Worm Gears for more information on this topic.
Custom Worm Gears
Worm Gears are right angle drives providing huge speed ratios on comparatively short center distances from 1/4” to 11”. When properly mounted and lubricated they function as the quietist and smoothest working type of gearing. Because of the high ratios possible with worm gearing, maximum speed reduction could be accomplished in less space than a great many other types of gearing. Worm and worm gears operate on nonintersecting shafts at 90° angles.
EFFICIENCY of worm gear drives depends to a big extent on the helix angle of the worm. Multiple thread worms and gears with higher helix position 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 higher lack of efficiency beyond other styles of gearing. The use of hardened and floor worm swith bronze worm gears raises efficiency.
LUBRICATION can be an essential factor to boost performance in worm gearing. Worm equipment action generates considerable heat, decreasing efficiency. The quantity of power transmitted at a given temperature increases as the performance of the gearing improves. Proper lubrication enhances efficiency by reducing friction and 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 units can be found with either remaining or right hand threads. Ever-Power. worm equipment sets can be found with Single, Dual, Triple and Qua-druple Threads.
Protection PROVISION: Worm gearing shouldn’t be used as a locking mechanism to carry large weights where reversing actions can cause harm or injury. In applications where potential damage is nonexistent and self-locking is desired against backward rotation then use of a single thread worm with a low helix angle immediately locks the worm gear drive against backward rotation.
MATERIAL recommended for worms is 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. In addition to steel and hardenedsteel, worms can be found in stainless, aluminium, bronze and nylon; worm gears are available in steel, hardened metal, stainless, aluminium, nylon and non-metallic (phenolic).
Ever-Power also sells gear 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 regular pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, Exterior Involute Splines, Metric Module “MOD”, Stub Tooth, Great Pitches, Coarse Pitches and Unusual Pitches. Refer to the section on GEAR GAGES for catalog numbers when ordering.
Why Not to Use Worm Gears