The Siren Board

Hello, I don’t know a lot about sirens yet but I came across a video of a whelen vortex slab rotator rotating and I can’t seem to figure out how it reverses rotation after hitting the kill switch. The video showed the rotator with the front panel off, the main bar that attaches to the siren has a bar and it eventually hits a little saucer shaped piece that activates on of two limit switches. The siren stops for a sec then rotates the other way u til it hits the other limit switch. I’m wondering how the siren reverses after hitting the limit switch? Why doesn't it just stop moving? Does anyone know?

The slab rotator test: https://www.youtube.com/watch?v=KhLjL39e_Ag

Whelen's controls reverse the voltage to the DC motor to reverse the rotation direction.