National Engineering Works manufactures Worm Wheel and Worm Shaft ( Worm Gear ) using superior quality Phosphor Bronze & Aluminium Bronze Casting in various design and dimension specification . All the three types of Worm Gears i.e. non throated , single and double throated , are acknowledged for their rugged construction and robust performance . These worm gears are the apt choice for a combination of high velocity ratio and right angle drive and they provide a large speed reduction ( up to 200 : 1 ) but with significant sliding in minimum possible space . Available in various sizes ( Up to Module 16 , Center Distance 12” , Worm Wheel O.D. 600 mm , Start 10 ) , these worm gears are designed to provide high angular velocity between the non intersecting shafts . Helically cut for maximum mating , worm wheels have conclave faces to fit the curvature of the Worm Pinion in order to offer line of contact instead of point contact . Depending on the lubricant type , lead angle , surface quality and installation condition , Worm Gears offer smooth and quiet operation and they are perfect for accurate transmission of torque .