The quintessential "Little Engine That Could." With a full tender of coal and water, MWRC #9 chugs slowly past my camera position pushing its lone coach toward the boarding platform adjacent to Marshfield Station. At slow speed, when the draft on the fire is not too strong, the engine makes a distinct ratcheting sound on the cog rack as it passes by. The little show she's putting on here is only a prelude to the one she'll put on when the throttle is opened for departure up Cold Spring Hill in just a few minutes. The little steam locomotives at Mt. Washington's Cog Railway are unique for sure. When you see them in operation, they appear for all of the world like the inspiration for the children's story: "The Little Engine That Could." They are built for one purpose only, and that's pushing a single coach to the top of Mt. Washington. These locomotives have four cylinders, two of which face forward and two face aft. These engines drive geared cogwheels at either end of the locomotive, which mesh with and apply power to the cog rack below. This railway uses the Marsh Rack System, which was designed by and named for Sylvester Marsh, the railway's builder. Sprag clutches are used to prevent roll-back during uphill operations. The locomotives roll on 4 free-turning wheels and have no drivers per se, hence the Whyte System 0-2-2-0 wheel configuration that is often used to describe them is really not technically correct. Although it appears as if the locomotive is coupled to the coach ahead of it, the truth is that there is no physical connection between the two, other than a signal cord running from the brakeman's position in the coach to the locomotive cab. The locomotive has a bumper on the front of the chassis which normally just butts against a butt plate on the back of the coach.
The most obvious odd feature of these locomotives is their distinctive, tilted boilers. The purpose of course is to keep the crown sheet covered with water when the locomotive is on a steep incline....and on this railroad, the inclines peak at 37.5%! Clearly visible is the inverted-Y-shaped, external dry-pipe, which carries the high-pressure steam from the steam dome to the cylinders. Along the base of the boiler, the exhaust pipe runs both forward to the smoke-box and aft, to the side-stack exhaust. This engine has no valve gear, so the Engineer must adjust the amount of back pressure that exhaust steam exerts on the piston, using side-stack valves. Side-stack steam is exhausted through the mast in front of the cab.
The little tender behind the engine holds a ton of soft coal and 700 gallons of water. With these supplies, she can make the ascent to the summit of Mt. Washington with just one water stop. Coming back down the hill, she uses her cylinders as a sort of "Jake Brake", not unlike a diesel truck, running just enough steam to lubricate and cool the cylinders. Very little coal or water are used coming down the hill, which is a really good thing....because she has very little left. Steam enthusiasts often wonder why there has never been a real, no-kidding photo charter on The Cog and there are good reasons for this. First, there are very few places on the mountain where passengers could safely get off, and second, these engines carry just enough supplies to go up and down the hill. They have virtually no reserves for conventional photo run-bys.
