Worm Gear and its appplications

1. What is Worm Gear & where worm gears are used? Fig. 1 (Worm Gear) Compared to other gears worm gears are unique and have different characteristics and applications. Worm Gear is a power transmission component used for high ratio reduction to change the direction of shaft rotation to reduce the speed and increase torque between non-parallel rotating shafts. In worm gear, there are worm which is screw and worm wheel with teeth, when rotational power is applied to the worm it transfers the power to the wheel. Gear is designed in a way which can rotate the worm wheel but the wheel cannot rotate the worm. 1

2. Working of Worm Gear Worm gears are a very compact type of gear which use for high-ratio speed reduction. These gears are used when there is space is limited and large gear reductions are required. Also, these gears are the smoothest and quietest of the gear system. As long as they are properly mounted and lubricated. Like a ball screw, the worm in a worm gear may have a single start or multiple starts – meaning that there are multiple threads, or helices, on the worm. A single-start worm advances the gear by one tooth with each full revolution (360 degrees) of the worm. A gear with 24 teeth will have a 24:1 gear reduction. The gear reduction for a multi-start worm is equal to the gear's number of teeth divided by the worm's number of starts. (This differs from the majority of other types of gears, where the ratio between the two components' diameters determines the gear reduction.) Fig 2 (Worm in worm gear assembly can have one thread to multiple threads) The Meshing of the worm and the gear is a mixture of sliding and rolling action, but sliding contact dominates at high reduction ratios. This sliding action cause friction and heat which limits the efficiency of the gear by 30 to 50%. To reduce friction worm and gear are made of different metals e.g., Worm is made of hardened steel and the gear is made of bronze or aluminium. Sliding operation reduces the efficiency but it provides a very quiet operation. Where noise should be reduced worm gears used. 2

3. Applications of worm gears Fig 3 (Worm gear in the elevator) Elevators: Worms are mainly used where required fast braking and stopping are required also because of their compact size, worm gears are used in elevators because of their proper size and ratio, they can stop and hold the load also they do not move reverse. Conveyors: conveyors are used in industrial applications to move products from one place to other. Worm gears are effective ways to provide the required torque increase and speed reduction required from electric motors to move the product efficiently. Automatic security gates: In Automatic security gates locked & closed they do not open in the reverse direction in security gates for open and close operation there are 2 worm gears are used one for opening and one for close. The ability to worm drive lock in place to ensure the gate remains in position and not forced to be breached. Conclusion: Worm gears are an economical method of reducing rotational speed and they are an integral part of many mechanisms, both simple and complex. They’re more practical for many applications than conventional gear kits because they require less space and they operate quietly. They’re also mechanically stable and have anti-reversing properties needed for some applications. SEIMITSU Factory Automation is an authorized distributor of KHK Worm Gear To Download Catalogue, click here Email Id: sales@seimitsu.in Contact no: +91 9028121211 #wormgear #wormdrive #wormandwormwheel #wormshaft #screwgear #wormdrivegearbox #speedreductiongearbox #seimitsu #seimitsufactoryautomation #distributor 3