Based on the failure characteristics of worm drive, the selection of worm gear and worm material combination requires not only sufficient strength, but also outstanding friction reduction, wear resistance and adhesive resistance. Practice shows that the more ambitious data of the worm pair is: bronze worm gear ring matching hardened grinding steel worm.

For high-speed and heavy-duty transmission, worm commonly used low carbon alloy steel after carburizing, surface quenching hardness of 56 ~ 62HRC, and then grinding. For medium speed and medium load transmission, worm commonly used 45 steel, 40Cr, 35SiMn, etc., the surface of the high frequency hardening hardness of 45 ~ 55HRC, then grinding. For the general worm can be used 45, 40 carbon steel tempering treatment.

The axial gear spacing of the worm should be the same as that of the worm gear, so the axial modulus of the worm should be the same as that of the worm gear. The axial pressure Angle of the worm should be equal to the end pressure Angle of the worm gear, the general standard pressure Angle α=20°. Worm equivalent to spiral, its spiral is also divided into left and right, single head and multi.

General worm head number Z1=1 ~ 4, the more head efficiency is higher; But the number of head too much, indexing error will increase, and not easy to process. In order to constrain the number of hobs, the value of worm characteristic coefficient which is adjusted with each module is specified in the specification. Generally, q=6 to 17. The diameter of worm gear indexing circle d2=Z2m.

Worm gear reducer by the transmission parts of worm gear and worm, shaft, bearing, box and its accessories. Can be divided into three basic structure: box, worm gear and worm, bearing and shaft combination. The box is the base of all the accessories in the worm gear reducer. It is an important part to support the fixed shafting parts, ensure the correct relative position of the transmission accessories and support the load on the reducer.

The function of worm gear is to transmit the motion and power between the two interleaved shafts. The primary function of bearings and shafts is to transfer power, work and improve efficiency. The oil cap and ventilator are used to discharge the gas inside the worm gear and reducer. The end cover is divided into large end cover and small end cover. The end cover is the axial orientation of the fixed shafting component and accepts the axial load. The oil seal is closed with the bearing cover at both ends of the bearing seat hole.