Worm Gears are correct angle drives providing large velocity ratios on comparatively short center distances from 1/4” to 11”. When correctly installed and lubricated they function as the quietist and smoothest operating type of gearing. Due to the high ratios possible with worm gearing, optimum speed reduction can be accomplished in less space than a great many other types of gearing.
EFFICIENCY of worm gear drives depends to a large extent on the helix angle of the worm. Nylon Gear Rack Multiple thread worms and gears with higher helix position prove 25% to 50% better than one thread worms. The mesh or engagement of worms with worm gears generates a sliding action leading to considerable friction and higher lack of efficiency beyond other types of gearing. The use of hardened and surface worm swith bronze worm gears raises efficiency.
LUBRICATION can be an essential factor to boost efficiency in worm gearing. Worm equipment action generates considerable high temperature, decreasing efficiency. The amount of power transmitted at confirmed temperature improves as the efficiency of the gearing raises. Proper lubrication enhances performance by reducing friction and heat.
RATIOS of worm equipment sets are dependant on dividing the number of teeth in the apparatus by the amount of threads. Thus single threads yield higher ratios than multiple threads.
Protection PROVISION: Worm gearing should not be used since a locking mechanism to carry weighty weights where reversing actions can cause harm or damage. In applications where potential harm is non-existent and self-locking is preferred against backward rotation then use of an individual thread worm with a low helix angle instantly locks the worm equipment drive against backward rotation.
Materials recommended for worms is hardened steel and bronze for worm gears. Nevertheless, depending on the application 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, aluminium, bronze and nylon; worm gears are available in steel, hardened metal, stainless, aluminium, nylon and nonmetallic (phenolic).
Gear racks are used to convert rotating movement into linear motion. A gear rack has straight teeth cut into one surface of a sq . or round portion of rod and operates with a pinion, which is 
a small cylindrical equipment meshing with the apparatus rack. Generally, equipment rack and pinion are collectively called “rack and pinion”. There are numerous ways to use gears.
There are applications where in fact the gear rack is stationary, while the pinion traverses and others where the pinion rotates upon a fixed axis while the gear rack moves. The previous is used widely in conveying systems while the latter can be utilized in extrusion systems and lifting/lowering applications.