These safety switches with mechanical time delay are used on MS-series double miter saws to positively lock the front cover in place. The switch is installed on the side of the machine frame, while the stainless steel actuator is fastened to the front cover (hood).
In order to release the front cover, the knob has to be rotated multiple turns. On the first turns the electrical contacts in the switch will positively open which will shut-off the saw motors immediately.
After about 20 seconds the actuator will be released and the front hood can be lifted up. This assures that the saw blades have enough time to come to complete stop before the cover is lifted.
In order to close the cover, the knob must be rotated in the opposite direction. The electrical contacts only close after the very last turns of the knob.