Why Not to Use Worm Gears
There is one especially glaring worm drive shaft reason one would not select 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 component to the tooth get in touch with or interaction. This makes them relatively difficult to lubricate.
The lubricants required are usually high viscosity (ISO 320 and higher) and thus are hard to filter, and the lubricants required are typically specialized in what they perform, 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 really is a boon and a curse simultaneously. The spiral motion allows large sums of decrease in a comparatively small amount of space for what’s required if a typical 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 sliding friction or sliding use.
With a typical gear set the power 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 is 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 absolutely no lubricant film 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 starts the procedure over again on the next revolution.
The rolling friction on a typical gear tooth requires little in the way of lubricant film to fill in the spaces and separate both components. Because sliding occurs on either part of the apparatus tooth apex, a slightly higher viscosity of lubricant than is usually strictly necessary for rolling wear must overcome that load. The sliding takes place at a comparatively low velocity.
The worm on a worm set gear turns, even though turning, it crushes against the strain that’s imposed on the wheel. The only way to avoid the worm from touching the wheel is 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 requires a special sort of lubricant. Not just will it should be a relatively high viscosity lubricant (and the bigger the strain or temperature, the bigger the viscosity must be), it will need to have some way to greatly help conquer 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 large swiftness ratios on comparatively short center distances from 1/4” to 11”. When correctly installed and lubricated they function as quietist and smoothest running type of gearing. Due to the high ratios feasible with worm gearing, optimum speed reduction can be accomplished in much 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 large extent on the helix position of the worm. Multiple thread worms and gears with higher helix position prove 25% to 50% more efficient than single thread worms. The mesh or engagement of worms with worm gears produces a sliding action leading to considerable friction and higher loss of efficiency beyond other types of gearing. The usage of hardened and ground worm swith bronze worm gears raises efficiency.
LUBRICATION can be an essential factor to improve performance in worm gearing. Worm gear action generates considerable heat, decreasing efficiency. The amount of power transmitted at a given temperature boosts as the performance of the gearing improves. Proper lubrication enhances effectiveness by reducing friction and temperature.
RATIOS of worm equipment sets are determined by dividing the number of teeth in the gear by the amount of threads. Thus solitary threads yield higher ratios than multiple threads. All Ever-Power. worm gear pieces can be found with either left or right hands threads. Ever-Power. worm gear sets are offered with Single, Dual, Triple and Qua-druple Threads.
SAFETY PROVISION: Worm gearing should not be used as a locking mechanism to carry heavy weights where reversing actions could cause harm or injury. In applications where potential harm is nonexistent and self-locking is desired against backward rotation then use of a single thread worm with a minimal helix angle immediately locks the worm gear drive against backward rotation.
Materials recommended for worms is hardened steel and bronze for worm gears. However, depending on the application 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 are available in steel, hardened metal, stainless, light weight aluminum, nylon and non-metallic (phenolic).
Ever-Power also sells gear tooth measuring products 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 recognize all the standard pitch sizes: Diametral Pitch “DP”, Circular Pitch “CP”, External Involute Splines, Metric Module “MOD”, Stub Tooth, Great Pitches, Coarse Pitches and Uncommon Pitches. Make reference to the section on GEAR GAGES for catalog numbers when ordering.
Why Not to Use Worm Gears