I realize it may be a little bit obsessive, but for me a steam engine with sound that does not imitate the prototype by chuffing 4 times for each driver revolution is terribly distracting. I realize this is a personal problem, but it is one shared by many steam fans. If you also suffer from this obsession with accurate chuff timing then perhaps a sound cam is for you.

Sound cams are mounted so they turn with the drivers. The cam signals the decoder when it should chuff. This means the sounds is always synchronized with the driver rotations. I am a huge fan of the sound cams offered by Grizzly Mountain Engineering. They require some modifications to the belly of the locomotive but the extra work is worth it if you are looking for reliable “chuff” synchronization. The pictures below show a cam in a HO scale Sunset 2-8-2, but there are cams available for a wide range of scales. There are even cams available for models of 3 cylinder locomotives that would have 6 chuffs per driver revolution, and cams for shays that I jokingly estimate chuff approximately 2 billion times for each wheel revolution. Anyone who has ever heard a real shay knows what I am kidding about.