Transitional Engine

A transitional engine (sometimes call a half-breed engine) is a steam engine from the late 1800’s that had been converted to an internal combustion and designed to run on oil or gas.

This engine is occupying a lot of my time and so thought it is about time it went onto my gallery page even if still a work in progress. You will have to bear with me as it progresses and I update different pages. It all started with the flywheel.

Glimpses of this engine along with some of the machining of parts are regulars on my instagram posts. Every single part of this engine is taking quite a lot of effort to design and to machine – part of the issue is the deign is in my head and evolves as the build progresses. The trick will be getting this engine to fire and run correctly.

scribbled drawing of horizontal steam engine
This all started as a scribbled horizontal steam engine

As per lots of my other engines this is being designed and built as I go and so there are no plans other than the virtual plans that exist in my head – the problem is these are sometimes transient in their own right.

The I-beam frame has taken a lot of effort to machine, but the result is superb.

The frame has been bolted together with mild steel stretchers, however, I’m thinking of either brazing the joints before final assembly or some small tac welds.

The I section of the beams is quite substantial and this is so that I can drill and tap the beam for fixings.

The crankshaft is described on a separate page as it was machined from a solid piece of mild steel.

The crankshaft has been back in the lathe a number of times to ensure that is absolutely correct and to slightly modify the webs. The image shows one of those times with a DTI being used to align the crank pin.

As this is a steam engine converted to an internal combustion engine it is only right that the connecting rod is in two pieces. I also decided that the corned should be made from mild steel. The bearings are all phosphor bronze.

The camshaft drive and bearing block has taken some time to develop with a number of iterations. The bottom end of this transitional engine is quite substantial.

The original cam design was very modern with a cam drive block that had an outer support. This design had stopped me in my tracks and so the engine had been sat on the side for several months.

The new idea is to use an eccentric cam design, this might be quite tricky to get running and so my first thought is that I need to do some calculations of sinusoidal cam movement versus the more modern cam lift profiles.

As much as there is a crankcase, it took some time to machine and had to be machined in order.

This part bolts down to the I-beam frame and the cylinder bolts to this.

This is made from mild steel, a good mix between ability to machine this and strength – this will react the combustion forces.

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