Abstract: A tool-rest driving device comprising a drive motor having its output shaft, a first rotatable shaft axially aligned with the motor output shaft and driven to rotate by the motor output shaft, a tool rest having at least one rotational tool, a reduction gear arranged between the first rotatable shaft and the tool rest for reducing the number of rotations of the motor output shaft, the tool rest being rotated at the reduced number of rotations, and a second rotatable shaft arranged coaxially of the motor output shaft for driving the rotational tool of the tool rest. A center axis of the rotational shaft, a center axis of the reduction gear and an axis of rotation of the tool rest are arranged on the same axis.

Abstract: A robot arm drive apparatus of an industrial robot comprising: an electric motor having a drive shaft; a first robot member having the electric motor mounted thereon; a second robot member rotatably supported on the first robot member; and reduction gear means for reducing rotation of the electric motor and then transmitting to the second robot member. The reduction gear means has a primary reduction gear for reducing the rotation of the electric motor and a secondary, planetary reduction gear for further reducing rotation of output of the primary reduction gear. The primary reduction gear has a reduction ratio such that the maximum number of rotations of the electric motor is reduced less than the characteristic torsion frequency of the drive system.