The above frontal view of a light cog railway locomotive is a relatively unusual one. In service, these engines typically never get more than a few feet from the coaches they push, so you virtually never get to see details that are visible here. First and foremost, the engine has no coupler and is never physically attached to its coach. She has a small roller bumper just below the smokebox door, which butts up against a hard plate on the rear of the coach. This arrangement is necessary because the grades change rapidly and a conventional coupler just would not work. Secondly, if you look below the locomotive, you will see a large set of reduction gears just to the left and right of the cog rack. Yes, this is most definitely a geared locomotive as the crankshaft that is turned by the steam engine spins significantly faster than the cogwheel, which is quite visible here, as it meshes with the rack. The Marsh Rack System, named after Cog Railway builder Sylvester Marsh, works a lot like the sprocket and chain on a bicycle. The cog wheel is the sprocket, and the cog rack is basically a chain laid flat. The torpedo-like appliance that you see under the Engineer's right hand is the feedwater heater, which is used to heat water from the tender, prior to pumping into the boiler. This enhances the efficiency of the boiler, because the water being injected is at a temperature significantly closer to that which is already in the boiler. Without it, each injection of cold water from the tender reduces the temperature of the water in the boiler and kills off steam pressure. Both of the Mt. Washington Cog Railway's active steam engines have this feedwater heater modification.