For small and medium-sized motors, there are two most common shaft extensions, namely cylindrical and conical. A careful observation reveals that motors used in lifting and metallurgy generally use conical shaft extensions, while most other load motors have cylindrical shaft extensions.

The cross-sectional diameter of the conical shaft extension is variable, so the torsional shear stress borne by the root of the shaft extension is much better than that of a straight shaft, and it is not easy to break the shaft due to metal fatigue caused by alternating stress. Therefore, it is suitable for mechanical equipment with large loads, high inertia, and frequent forward and reverse rotation. It goes without saying that conical shaft extensions are chosen for lifting and metallurgical motors.

Most of our most common YZ, YZR and YZP series motors used in lifting and metallurgical equipment use tapered shaft extensions. Compared with ordinary cylindrical shaft extensions, the processing and inspection of tapered shaft extensions are relatively complicated, especially when ordinary lathes are used to process shafts, which requires higher skills of the operators. However, this problem is easily solved when CNC lathes are used for processing.

The motor shaft extension is an important installation dimension. If the processing is unqualified, it will affect the connection with the main engine, fail to effectively transmit torque, and even cause the equipment to vibrate. It is very important to know how to check the motor shaft extension size.

For tapered shaft extensions, it is obviously not possible to measure the outside diameter of ordinary shaft extensions with a micrometer. In order to solve this problem, a special gauge is usually used for measurement, which is what we usually call a tapered ring gauge. The tapered ring gauge is a special comprehensive measuring tool for checking the diameter, taper and length of a tapered shaft extension.

The characteristic of this ring gauge is that one specification of shaft extension corresponds to a special measuring tool. No matter there are any differences in taper, diameter and length, there is no universality. The inspection with a taper ring gauge is actually to check the matching relationship between the two. The conventional practice is to apply red lead powder for benchwork on the shaft extension along the axial direction, and then insert the ring gauge. After the two are axially matched in place, rotate the ring gauge for more than one circle, and then check the running-in state of the coating. The basis for judging whether it is qualified is that the close fitting area of the two exceeds 70%.