Why Not to Use Worm Gears
There is one especially glaring reason one would not choose a worm gear over a typical gear: lubrication. The motion between your worm and the wheel gear faces is completely sliding. There is no rolling component to the tooth get in touch with or conversation. This makes them fairly difficult to lubricate.
The lubricants required are often high viscosity (ISO 320 and greater) and therefore are tough to filter, and the lubricants required are usually specialized in what they do, requiring a product to be on-site particularly for that kind 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 large sums of reduction in a comparatively small amount of space for what is required if a standard helical equipment were used.
This spiral motion also causes a remarkably problematic condition to be the primary mode of power transfer. This is often called worm drive shaft sliding friction or sliding put on.
With a typical 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 occurs on either side of the apex, but the velocity is relatively low.
With a worm gear, sliding motion may be 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 still left, and for that reason, the worm rubs at the metal of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface, it picks up more lubricant, and begins the procedure over again on another revolution.
The rolling friction on a typical gear tooth requires little in the way of lubricant film to fill in the spaces and separate the two components. Because sliding occurs on either part of the gear tooth apex, a somewhat higher viscosity of lubricant than is usually 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, even though turning, it crushes against the load that’s imposed on the wheel. The only way to avoid the worm from touching the wheel is certainly to possess a film thickness huge enough to not have the entire tooth surface wiped off before that part of the worm has gone out of the load zone.
This scenario requires a special sort of lubricant. Not only will it should be a relatively high viscosity lubricant (and the higher the load or temperature, the bigger the viscosity should be), it must have some way to help conquer 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 huge quickness ratios on comparatively brief center distances from 1/4” to 11”. When properly mounted and lubricated they function as the quietist and smoothest running type of gearing. Because of the high ratios possible with worm gearing, maximum speed reduction can be accomplished in much less space than many other types of gearing. Worm and worm gears operate on 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 angle prove 25% to 50% better than one thread worms. The mesh or engagement of worms with worm gears generates a sliding action causing considerable friction and higher loss of efficiency beyond other types of gearing. The utilization of hardened and floor worm swith bronze worm gears raises efficiency.
LUBRICATION is an essential factor to improve efficiency in worm gearing. Worm equipment action generates considerable temperature, decreasing efficiency. The quantity of power transmitted at confirmed temperature improves as the effectiveness of the gearing improves. Proper lubrication enhances efficiency by reducing friction and temperature.
RATIOS of worm gear sets are determined by 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 models can be found with either still left or right hands threads. Ever-Power. worm gear sets are offered with Single, Double, Triple and Qua-druple Threads.
Basic safety PROVISION: Worm gearing shouldn’t be used as a locking mechanism to hold heavy 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 an individual thread worm with a minimal helix angle instantly locks the worm equipment drive against backward rotation.
Materials recommended for worms is usually 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, aluminium, bronze and nylon; worm gears can be found in steel, hardened steel, stainless, light weight aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells gear tooth measuring gadgets called Ever-Power! Gear Gages decrease mistakes, save time and money when identifying and buying gears. These pitch templates can be found in nine sets to identify all the regular pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, Exterior Involute Splines, Metric Module “MOD”, Stub Tooth, Good Pitches, Coarse Pitches and Uncommon Pitches. Refer to the section on GEAR GAGES for catalog amounts when ordering.