Shaft, shapes of

Broadly speaking, there are two types of shaft ends as shown below. Cylindrical shaft end (standardized in JIS0903)
Conical, or tapered, shaft end with 1/10 cone taper ratio (standardized in JIS0904)

Cylindrical shaft ends are mainly used in small servomotors in recent years, but conical shaft ends are sometimes used in direct drives, in which it is important to maintain concentricity of the motor and load. In addition, a key groove machined to the shaft end, as shown in Fig. (c), is sometimes used to transmit torque from motor to load while preventing slipping.