Short demonstration of a HK Porter, mine locomotive that runs off of compressed air. As you can see in the video the locomotive does not run very long with the air in the tank. Normally the locomotive would have a air hose hooked up to it suppling air all the time for operation. Locomotive has no brakes, and braking is accomplished by putting the locomotive into reverse and opening the throttle. This locomotive was built in 1906 and is 24" gauge. This was shot at the Western museum of mining near Colorado Springs, Colorado.