to answer "How they work", there are two plates with a hole in the center. The metal is shaped/dimpled into the hole. A rubber o-ring goes between the two plated. As you squeeze the brake lever, the cable tightens and applies pressure to the plates, squashing the o-ring until the two dimples touch, closing the electrical circuit to the brake lights.
Over time the o-ring dries out and cracks & falls out. Then the lights are on all the time. Replace o-ring and all is fine. NOTE: o-ring needs to be made out of the right material so it squashes correctly.
The two switches you show, the black is the aftermarket type, and the white is a repo Rupp style. My Speedway Green Horn had the black style on it and it looked original. I had to replace the o-ring and a piece of plastic that was missing and caused the one plate to short to ground. Also, the Speedways had the switch mounted at the brake assembly side. Same principle of operation.
Over time the o-ring dries out and cracks & falls out. Then the lights are on all the time. Replace o-ring and all is fine. NOTE: o-ring needs to be made out of the right material so it squashes correctly.
The two switches you show, the black is the aftermarket type, and the white is a repo Rupp style. My Speedway Green Horn had the black style on it and it looked original. I had to replace the o-ring and a piece of plastic that was missing and caused the one plate to short to ground. Also, the Speedways had the switch mounted at the brake assembly side. Same principle of operation.