An automatic switch-off torque limiter, designed to prevent damage by excessive torque.

This torque limiter was designed for my mechanical loom. In deed, it was not enough reliable and when problems occurred, I wanted to have an automatic system which switched-off the power to prevent damages. I have chosen to design this system with a manually rearmament because when a problem occurred, there were often some blocking, thus before restarting, the problem had to be fixed.

I used a well-known principle for this device : differential. The 24-tooth gear of the differential is connected to the switch and the planetary gears are connected to the XL motor. In normal operating state, the torque goes by the planetary gears. When a high torque comes, the torque tends to make rotate the 24-tooth gear of the differential, and as it is connected to the switch, when the gear rotates, the switch switches-off.

The detection point for this device is set by the black gear on the front. If the gear ratio comes up, the maximum torque is decreased and vice versa. To finish, this device can be modified to allow automatic rearmament if the final device needs it (like an pneumatic anti-high pressure device) by putting a spring of a rubber band of the lever.

I have made the simple building instructions as a photo sequence.