worm drive shaft

Why Not to Use Worm Gears
There is one particularly glaring reason one would not choose a worm gear more than a standard gear: lubrication. The movement between the worm and the wheel gear faces is completely sliding. There is no rolling element of the tooth get in touch with or interaction. This makes them relatively difficult to lubricate.
The lubricants required are often very high viscosity (ISO 320 and greater) and therefore are tough to filter, and the lubricants required are typically specialized in what they do, requiring a product to be on-site particularly 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 at the same time. The spiral motion allows huge amounts of reduction in a comparatively small amount 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 principal mode of power transfer. That is commonly known as sliding friction or sliding put on.
With an average 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 occurs on either part of the apex, however the velocity is fairly low.
With a worm gear, sliding motion is 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 absolutely no lubricant film left, and as a result, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface, 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 way of lubricant film to fill in the spaces and separate the two components. Because sliding occurs 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 relatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the strain that’s imposed on the wheel. The only method to avoid the worm from touching the wheel is definitely to possess a film thickness huge enough to not have the entire tooth surface area wiped off before that section of the worm is out of the strain zone.
This scenario requires a special kind of lubricant. Not just will it will have to be a comparatively high viscosity lubricant (and the higher the load or temperature, the bigger 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 correct angle drives providing large speed ratios on comparatively brief center distances from 1/4” to 11”. When properly installed and lubricated they function as quietist and smoothest running type of gearing. Due to the high ratios possible 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 non-intersecting shafts at 90° angles.
EFFICIENCY of worm gear drives depends to a big extent on the helix position of the worm. Multiple thread worms and gears with higher helix position prove 25% to 50% more efficient than one thread worms. The mesh or engagement of worms with worm gears produces a sliding action leading to considerable friction and higher lack of efficiency beyond other types of gearing. The utilization of hardened and floor worm swith bronze worm gears improves efficiency.
LUBRICATION can be an essential factor to improve performance in worm gearing. Worm gear action generates considerable temperature, decreasing efficiency. The quantity of power transmitted at a given temperature improves as the performance of the gearing raises. Proper lubrication enhances performance by reducing friction and high temperature.
RATIOS of worm gear sets are determined by dividing the amount of teeth in the gear by the amount of threads. Thus solitary threads yield higher ratios than multiple threads. All Ever-Power. worm gear sets are available with either remaining or right hand threads. Ever-Power. worm gear sets can be found with Single, Double, Triple and Qua-druple Threads.
Basic safety PROVISION: Worm gearing should not be used since a locking mechanism to hold large weights where reversing action could cause harm or injury. In applications where potential harm is non-existent and worm drive shaft self-locking is desired against backward rotation then use of an individual thread worm with a minimal helix angle automatically locks the worm gear drive against backward rotation.
MATERIAL 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 steel and hardenedsteel, worms are available in stainless, aluminium, bronze and nylon; worm gears can be found in steel, hardened metal, stainless, aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells gear tooth measuring devices called Ever-Power! Gear Gages reduce mistakes, save money and time 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”, Exterior Involute Splines, Metric Module “MOD”, Stub Tooth, Fine Pitches, Coarse Pitches and Unusual Pitches. Refer to the section on Equipment GAGES for catalog figures when ordering.


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