British Class E2, Thomas the Tank Engine

The other day I was watching Thomas the Tank Engine with my son (got to start them early!). I notived that the Thomas engine had no steam cylinders that I could see. At first I assumed it was a modeling license, but then I noticed the other locomotives actually had running gear.

I looked up the show, and Thomas is based on a british class E2. A quick search on the internet and I found some photos of the class, such as this;
http://afu.com/steam/

Note that this locomotive has a rod that connects the three axles, but does not seem to have any other running gear, steam cylinders, etc.

My question is does anyone know how this class was powered? Internal (hidden) steam cylinders? Something along the lines of a shay?

When my son is old enough he will be asking these questions, I need the answers!

Many smaller British steam locomotives had inside cylinders and rods like the E-2 (Thomas) class.

Stuart

Thanks for the reply.

In the case were there were internal cylinders how would they drive the wheels? I would picture the axle getting in the way unless it was shaped like a crankshaft, or there were not axles on some of the wheels. You wouldn't have a diagram or picture of this mechanism by any chance...

Thanks again,

The Proton

The axle which the main rod was connected to was constructed with cranks in it. Mattering by the angle which the mainrod was set any axles ahead of the main axle were also cranked for clearence.

There were many steam locomotive built with both inside and outside cylinders (Union Pacific's 4-12-2's and the Gresley A-3 "Flying Scotsman" 4-6-2) as two examples).

The biggest problem with inside cylinders is maintenance. Getting in between the frames was a major headache, and unless there was no other way to get the extra power many railroads preferred to use two larger cylinders, and/or higher boiler pressure instead of inside cylinders.

Stuart