Why Not to Use Worm Gears
There is one especially glaring reason one would not choose a worm gear more than a typical gear: lubrication. The movement between your worm and the wheel equipment faces is entirely sliding. There is no rolling element of the tooth contact or conversation. This makes them fairly difficult to lubricate.
The lubricants required are usually very high viscosity (ISO 320 and higher) and thus are hard to filter, and the lubricants required are usually specialized in what they do, requiring something to be on-site specifically for that kind of equipment.
Worm Gear Lubrication
The main 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 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 commonly known as sliding friction or sliding put on.
With an average 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, however 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 left, and as a result, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface area leaves the wheel surface, it picks up more lubricant, and begins 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. worm drive shaft Because sliding happens on either part of the gear tooth apex, a somewhat higher viscosity of lubricant than is usually 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 load that’s imposed on the wheel. The only method to prevent the worm from touching the wheel is definitely to get a film thickness large enough never to have the entire tooth surface area wiped off before that part of the worm is out of the load zone.
This scenario requires a special sort of lubricant. Not only will it will have to be a comparatively high viscosity lubricant (and the higher the strain or temperature, the bigger the viscosity should be), it will need to have some way to help overcome 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 correct angle drives providing large quickness ratios on comparatively short center distances from 1/4” to 11”. When correctly mounted and lubricated they function as quietist and smoothest working type of gearing. Because of the high ratios feasible with worm gearing, maximum speed reduction can be accomplished in 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 large level on the helix angle 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 generates a sliding action causing considerable friction and better loss of efficiency beyond other styles of gearing. The utilization of hardened and floor worm swith bronze worm gears raises efficiency.
LUBRICATION can be an essential factor to improve efficiency in worm gearing. Worm equipment action generates considerable high temperature, decreasing efficiency. The amount of power transmitted at a given temperature increases as the performance of the gearing raises. Proper lubrication enhances performance by reducing friction and heat.
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 units are available with either left or right hands threads. Ever-Power. worm equipment sets are offered with Single, Double, Triple and Qua-druple Threads.
Basic safety PROVISION: Worm gearing should not be used since a locking mechanism to hold heavy weights where reversing actions could cause harm or damage. In applications where potential harm is non-existent and self-locking is desired against backward rotation after that 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 certainly hardened steel and bronze for worm gears. Nevertheless, depending on the application form unhardened metal worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. Furthermore to metal and hardenedsteel, worms are available in stainless, aluminum, bronze and nylon; worm gears are available in steel, hardened steel, stainless, aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells equipment tooth measuring products called Ever-Power! Gear Gages decrease mistakes, save money and time when identifying and ordering 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, Good Pitches, Coarse Pitches and Uncommon Pitches. Make reference to the section on Equipment GAGES for catalog quantities when ordering.
Why Not to Use Worm Gears