Chinese Steam

Chinese steam - SY 0770 struggles on slippery rails
I first saw this video a year ago and left this comment on the YouTube page:

Surprising video. The opening scene looks like someone's model railroad. The juddering noise that the train makes when the wheels slip was unexpected. Did you notice the way the second trike tilted when it ran over a rock just before parking? The driver gets out, walks around the back, picks up the rock and puts in front of the left rear wheel. I always thought the chuffing of the steam engine was from steam expended from the cylinders, but watching the wheels slowly turning while the engine chuffs away tells me that is not the case.

Today I got a reply from Varinki that explains the chuffing noise:

 The fast continuous chuffing is the exhaust from the air brake pump.

An air compressor! It's obvious when you think about it. Trains use air brakes, which means you need an air compressor, and since you are running a steam engine what else would you use to power it besides steam?

8 1/2" Cross Compound Compressor.  The steam cylinders are at the top and the air compressor cylinders are on the bottom.  The high pressure steam and low pressure air cylinders are on the right.

These air compressors are quite a hunk of machinery in their own right, but compared to the locomotive they are minuscule, which is why they are often overlooked. I think you can see the one in the video after the 5 minute mark. At 5:45 is just above the motorcyclist's helmet.

The man who made this video, Wolfgang Cloessner, was a bit of a player in the steam engine world. He died two years ago.

Come to think of it, if your train needs any electrical power you are going to have a steam powered electrical generator as well.