
2.HOW TO USE SERVO MOTORS SPECIFICATIONS FOR THE αiS/αi SERIES B-65262EN/03
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Direct connection using a flexible coupling
Direct connection by a flexible coupling has the following advantages
over connection using gears:
• Even if the angle of the motor shaft to the ball screw changes, it
can be compensated to a certain extent.
• Because a flexible coupling connects elements with less
backlash, driving noise from joints can be significantly
suppressed.
However, this method has the following disadvantages:
• The motor shaft and the ball screw must not slide from each
other in the radial direction (for single coupling).
• Loose assembly may result in lower rigidity.
When the motor shaft needs to be connected directly to the ball screw,
connecting them using a flexible coupling facilitates adjustment and
installation of the motor.
To use a single coupling, the machine needs to be designed so that the
centers of the motor shaft and the ball screw are aligned. (In the same
way as with a rigid coupling, the use of a single coupling demands
that there be almost no relative eccentricity between the axes.)
If it is difficult to align the centers, a double coupling needs to be
employed.
Flexible
coupling
Ball screw
Motor shaft
Locking
element
Flexible
coupling
Ball screw
Motor shaft
Locking
element