Running steam engines on air

Ready to go - tested on air

Meccano steam engines were originally intended as toys in a time when children and adults a like were expected to evaluate danger for themselves. As kids we knew that some things could hurt us and we would treat them with caution and respect. Yes we did come a cropper sometimes, but we learnt from our mistakes. I now know why it is not a good idea to build a see-saw from a ladder and a 20 Gallon barrel and use a lawnmower as a counterweight!

Today the world is a different place and the only danger that has increased is the risk of litigation. There are a whole bunch of companies, and people, looking for an excuse to sue each other. Because of this we have labels on the packet of craft knife blades warning that the contents are sharp and I had a packet of almonds, the other, day that had a line of text on the back of the packet that read "Contains Nuts".

Sadly this stupidity has caused many event organisers to steer on the safe side and ban the use of live steam Meccano engines run on fire and water as they should be. Personally I don't bother to run engines at such meetings, preferring to use a totally safe form of propulsion such as an electric motor... Yeh, right! But that is another debate for another page.

We use compressed air, here at Laughton Towers, for all sorts of things from nailing and sanding to spraying and airbrushing. We also use it to test our newly refurbished engines before we fire them.


What do you need?

A compressor or some other kind of regulated supply of air, (this is another whole new subject and I will not get bogged down with it here) a boiler adapter, a suitable compressor fitting and hose.

Boiler fitting

The boiler fitting is available from internet toy steam suppliers and will screw into the safety valve threaded insert. Safety is catered for by regulating the air pressure and using a hose that will not hold tight to the fittings if the pressure increases. DO NOT crimp or secure the hose to the fitting, just push fit is good enough.  

Hose is a simple push fit onto the fittings
I use an old Badger airbrush fitting at the compressor end. The tube is automotive screen washer hose available in most motor factors or from the internet.

Pressure gauges
Air regulation is the most important part of the operation. Regardless of type or size, your compressor must be fitted with a regulator, this can be mounted on the machine, as mine is, or can be fitted into the air line. A moisture trap will be helpful too. This will prevent and chance of moisture being injected into the cylinder. In practise, it will probably only get as far as the boiler, as this will act as a moisture trap, but if you are intending to use your airline for spraying you will need one anyway. The picture to the right shows the gauges on my small, silent, compressor. The top one shows the line pressure (set by the regulator) and the lower gauge shows the tank pressure, that is at its lowest at the time of this picture being taken, and is about to recharge. A pressure of about 15psi (just a bit over 1bar) is more than adequate to run any small engine.

Now all you need to do is to connect up the hose and fittings, set the air flowing and flick the wheel...

Ready to go!
Here is a short video showing my steam Ferris wheel running on air.

...and just to prove it doesn't always work first time, especially if there is a camera pointing at it, take a look at this short video.I cut the last few seconds off as I am sure you don't what to hear what I said!



  1. I still have my SE3 2 cylinder model and it works, i had it in 1959 when i was 9! £5!

  2. Don't forget when running on air use mineral oil as a lubricant in the cylinders. Steam oil only works with steam! When changing from air to steam or vice versa you will need to wipe off any previous oil.
    I usually buy Singer sewing machine oil for running on air.

  3. I run a Stuart beam engine quite successfully using an aquarium air pump at about 4 psi. There is a gate valve in the airline, to stop the engine running too fast.