The Front or Engine Truck

While getting the pivot ready to bolt into the frame, I couldn’t quite figure out at what height to mount it and couldn’t figure out how the frame was supported on it. So I decided to start from the ground up and the side frames

The pattern out of MDF

It will take two patterns to cast one frame. I decided to not cut out for the axle journals because it may have made them weak

Then I started working on the mount to the frame and the center pin for the engine truck and here is the finished product.

I still need to cut out the bushing for the truck to first axle equalizer. It fits into the center pin through the bushing, and on an equalizer seat. The center pin does not turn in the bushing, only up and down. The rotating motion will be between the bolster and center pin and the side to side swing will be between the bolster and what is called the roller seat. On a steamer the engine truck (when going into a turn) will be forced down on the rails to prevent derailment. The bottom of the bolster and the roller plate will have two v groves running fore and aft (1 in 3 on the sides). A rack gear at the same angles and a gear between the bolster and roller plate will provide the added weight shift hill.

And this is how they turned out

With a bit more machining done

An axle box pattern

Getting close

The inner workings are a bit of a trick. As the engine enters a curve two things happen, First this assembly turns and secondly it must shift to the side. As it shifts to the side it needs to transfer weight to the assembly to keep it from derailing this is what does the trick