Why Not to Use Worm Gears
There is one especially glaring reason why one would not select a worm gear more than a standard gear: lubrication. The motion between your worm and the wheel equipment faces is completely sliding. There is no rolling component to the tooth contact or conversation. This makes them relatively difficult to lubricate.
The lubricants required are usually very high viscosity (ISO 320 and higher) and therefore are hard to filter, and the lubricants required are usually specialized in what they do, requiring a product to be on-site particularly for that type 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 large sums of decrease in a comparatively small amount of space for what’s required if a standard helical gear were used.
This spiral motion also causes a remarkably problematic condition to be the primary mode of power transfer. This is often called sliding friction or sliding wear.
With an average gear set the power is transferred at the peak load point on the tooth (referred to as the apex or pitchline), at least in a rolling wear condition. Sliding happens 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 gradually rubs off the lubricant film, until there is 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 area, it picks up more lubricant, and begins the process over again on another revolution.
The rolling friction on a typical gear tooth requires small in the way of lubricant film to complete the spaces and separate the two components. Because sliding occurs on either side of the gear tooth apex, a somewhat worm drive shaft higher viscosity of lubricant than is certainly strictly necessary for rolling wear must overcome that load. The sliding takes place at a relatively low velocity.
The worm on a worm set gear turns, even though turning, it crushes against the strain that is imposed on the wheel. The only method to prevent the worm from touching the wheel is certainly to get a film thickness huge enough never to have the entire tooth surface area wiped off before that section of the worm is out of the strain zone.
This scenario takes a special kind of lubricant. Not just will it should be a relatively high viscosity lubricant (and the higher the strain or temperature, the bigger the viscosity must be), it must have some way to greatly help overcome the sliding condition present.
Read The Right Way to Lubricate Worm Gears for more information on this topic.
Custom Worm Gears
Worm Gears are right angle drives providing huge rate ratios on comparatively brief center distances from 1/4” to 11”. When properly installed and lubricated they function as quietist and smoothest working type of gearing. Because of the high ratios feasible with worm gearing, maximum speed reduction could 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 equipment drives depends to a large extent on the helix angle 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 produces a sliding action causing considerable friction and better loss of efficiency beyond other types of gearing. The utilization of hardened and floor worm swith bronze worm gears increases efficiency.
LUBRICATION can be an essential factor to boost performance in worm gearing. Worm gear action generates considerable temperature, decreasing efficiency. The quantity of power transmitted at confirmed temperature raises as the performance of the gearing improves. Proper lubrication enhances efficiency by reducing friction and high temperature.
RATIOS of worm equipment sets are dependant on dividing the number of teeth in the apparatus by the number of threads. Thus solitary threads yield higher ratios than multiple threads. All Ever-Power. worm gear sets can be found with either left or right hand threads. Ever-Power. worm equipment sets are offered with Single, Double, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing should not be used since a locking mechanism to carry heavy weights where reversing action could cause harm or injury. In applications where potential damage is non-existent and self-locking is preferred against backward rotation then use of a single thread worm with a low helix angle immediately locks the worm equipment drive against backward rotation.
MATERIAL recommended for worms is hardened steel and bronze for worm gears. Nevertheless, depending on the application unhardened steel worms operate adequately and more economically with cast iron worm gears at 50% horsepower ratings. Furthermore to metal and hardenedsteel, worms can be found in stainless, aluminum, bronze and nylon; worm gears are available in steel, hardened steel, stainless, aluminium, nylon and nonmetallic (phenolic).
Ever-Power also sells gear tooth measuring gadgets called Ever-Power! Gear Gages reduce mistakes, save money and time when identifying and ordering gears. These pitch templates are available in nine sets to recognize all the regular pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, Exterior Involute Splines, Metric Module “MOD”, Stub Tooth, Good Pitches, Coarse Pitches and Unusual Pitches. Refer to the section on GEAR GAGES for catalog figures when ordering.
Why Not to Use Worm Gears