I’ve got a day off work today, so it’s time to get something done about the FCPyF’s new tank engine.
While it has been sat at Cuarto Sheds for the last couple of days I have been looking at its apparent balance on the wheels.
The Mogul looks fine as built, but as a tank engine it definitely looks wrong. The bunker extension on the rear of the cab throws it out.
So, what are the options?
The most obvious choice, and perhaps the easiest to do, would be to add a set of carrying wheels immediately behind the firebox as hinted at in the previous blog entry. But I’m not keen on the loco’s appearance as a Prairie, and the trailing axle may interfere with the rear coupler mounting, so I’ve dismissed this idea.
So how about shortening the front end and removing the leading pony truck? Better. Much better indeed as an 0-6-0ST. Those of us used to seeing British steam locos, where the boiler backhead usually sits well forward in the cab, may think it now looks front-heavy but removing the cab shows that the weight is pretty evenly distributed.
The main weight of the loco, the combined boiler and firebox (yellow line), actually sits slightly aft of the loco’s wheelbase but in theory is balanced partly by the cylinder casting (immediately in front of the wheels) and partly by the water tank (front orange line). The tank and fuel bunker (both orange lines) off-set each other visibly but in the general scheme of things the bunker would not affect the balance much. When looked at again knowing how the firebox sits in the cab and ignoring the cowcatcher, which would add little weight anyway, the loco’s overhang at each end (shown by the red lines) is almost perfectly balanced.
Having decided upon the 0-6-0ST arrangement I proceeded with the conversion, this time using a hacksaw instead of photoshopping.
The tank is gradually being filled, with filler, logically, until it sits level on the boiler. I’ve opted to mount the fuel bunker quite low behind the cab, this will make it easier to create the rear coupling mount and a step pilot.
While the cab was off the loco I removed the glazing and made a start on painting it. This, and an undercoat of black on the tank and boiler fittings, blends things together a bit better than they looked in the previous photos. There’s still quite a way to go before the rebuilt loco is ready for traffic but at least it looks the part already. A big advantage of playing around with the images before committing to the saw!