The project is based on this locomotive, a 2-6-6-2T Logging Mallet that once ran for the Clover Valley Lumber Company. This locomotive doesn’t exist in HOn3 space.
Then I came across this eBay listing.
This is an old Roundhouse kit that allows the construction of a static (non-powered) steam engine. The photo shows an 0-8-0T. But this kit was designed for kit bashers – like me. The kit offers another option, a 2-4-4-0T articulated shown in the bottom of the following photo. This engine would never have existed in the real world. But it sure fired my imagination!
If you look at the parts set, it includes the components to model the above 2-4-4-0T. If you look more closely, the frame and running components are the same as those in the Outside Frame Roundhouse 2-8-0 Consolidation kit with the exception of the connecting rods and piston rods. But as you can see, these parts are in the kit. If you compare the two kits in the following photos, the locomotive frame is the same as are the counterweights and under frame. There are two sets of pistons in the bag as well as the drivers. There are two sets of piston rods.
I happen to have two of the 2-8-0 kits. Those two kits are powered. I also have quite a few brass detailed parts, an extra set of drivers and extra front and rear two wheel trucks that are part of the extended parts set in one of the two kits shown in the following image. The parts set has a set of drivers in the upper left corner, a set of tender trucks, and front and rear pilots. There is a second set of tender trucks under the tender. There is also another complete set of drivers in the box on the right side. There is a fairly complete set of brass detail parts. Not shown is two brass domes (one sand and one steam) a brass air compressor, and a brass pilot I picked up in separate auctions.
I know how to make these kits run smoothly. The drive train parts are available from North West Short Line – gearbox, axle gear, and can motor. You can see that the 2-8-0 parts set already has upgraded NWSL gears. Did I mention that all three are HOn3 kits?
The 2-4-4-2T would be created by cutting the frame for a 2-8-0 Consolidation in half and inserting an additional pair of cylinders from the 3 in 1 kit. The boiler-tank-cab-bunker from the 3 in 1 kit is almost perfect in size for this locomotive.
The next logical step might be to use a Roundhouse 2-8-0 Outside Frame kit and a 3 in 1 kit to produce a 2-6-6-2T like the Clover Valley Mallet. The first frame would be cut into a 2-6 block by removing the last driver pair and the remainder of the rear frame.
The second frame would be cut into the 6-2T block by removing the front driver pair and the rest of the front part of the frame. The second set of cylinders would go between the two driver blocks.
The boiler would need to be extended to deal with the longer frame. The boiler diameter is from the 3 in 1 kit is 3/4″. Plastruct makes a tube in that diameter with 1/16″ walls. Or the size of the boiler could be upgraded to 7/8″ or 1″.
Side rods could be cut down to handle a six coupled driver set rather than the eight coupled sets in both kits. Cylinder mounting would be similar to the 2-4-4-2T including piston rods, yokes, etc.
Note that this is an outside frame locomotive and the Baldwin Mallets were all inside frame engines. But virtually all of them are standard gauge locomotives with 4′ 8″ between the rails. Had Baldwin been asked to produce a logging Mallet for 3′ 0″ narrow gauge, they may well have recommended an outside frame. An inside frame locomotive would be a bit tippy on curves if armed with a large boiler. Given this is a freelance locomotive and the parts are outside frame parts hopefully the rivet counters will forgive me for deviating from the norm.
Of course there is the difference in the cylinder sizes to deal with. Or is there? I was poking around on Jon Davis’s web site, Mallets in the Tall Timber and came across his discussion of simple Mallet Type Articulateds like Weyerhaeuser 111 with both sets of Cylinders the same size. Note the double stack.
At his site Jon has a very useful discussion of the advantages of simple versus compound Mallets including this drawing of the steam routing on a Simple Mallet Type Articulated.
Check out his discussion on this page and let Jon fill you in on the details.
Powering this unit would be less of a challenge than with the 2-4-4-2T as there would be plenty of room to mount two motors. The 2-8-0 Consolidation powers the second driver pair from the front, That driver pair exists on both driver blocks.
Given that this is an easier bash than the 2-4-4-2T, I think I will take it on first. A builders log will be maintained. Individual posts for that blog will be shown below.