Technical Data  Reducers  Small-Size Gear Motor  Technical Data

About Self-Lock

In the static condition, the input shaft (motor shaft) of a worm reducer (Croise motor) will not start to rotate even if the output shaft of the reducer is caused to rotate. This effect is called "self lock." In addition, although the input shaft (motor shaft) will rotate, a large force would have to be applied on the output shaft to make this happen. This effect is called the "self-locking effect" or "braking effect."

This self-locking effect depends on the lead angle of the worm gear, the condition of the tooth surfaces, and the lubricating oil.

In our standard specification worm reducer (Croise motor), the self-locking effect can be expected in the static condition when the reduction ratio of the worm gear is 1/60.

The self-locking effect and the braking effect can also be anticipated at other reduction ratios (1/10 to 1/50).

However, the self-locking effect may be diminished if the reducer is subject to shock or external vibrations. When reliable reverse rotation ("back driving") prevention is required, a brake option is recommended.

Also, in applications where the load inertia is very large (such as transport devices or circulating movement equipment), sudden braking may occur due to the self-lock or self-locking effect, which is extremely dangerous.

For such applications, select a lower worm gear reduction ratio of 1/10 to 1/20.