Bicycle Powered Compressor
Pedaling the Brumby

There are situations where manual pumps are required. That can be in remote areas where there is no power or money for fuel or as an emergency back-up in case of a disaster. As clean water is neccessary to the survival of man and beast, it is useful to have a brumby pump and some kind of manually operated compressor ready for when things go pear shaped. The Brumby is very quick and easy to install in a bore/well or other water source and can be a life saver.

As the Brumby Pump operates on compressed air, it is extremely versatile. It doesn't matter how the air is compressed. It just matters that there is some positive air flow and enough pressure for the lift.

It is uneconomic for us to commercially produce a bike powered compressor at the moment, so we thought we would build one cheaply, from scrap and show you how you can build one for yourself with materials and components you may have laying around your property - assuming you can use a grinder and welder and have a little mechanical aptitude.

We used an old bike, a small compressor that was bought some time ago from a garage sale, lengths of steel tubing from the "resources pile" and some basic tools. The total cost came to around $50, which included the compressor (air pump) and purchase of a steel plate to mount it on

Ok, so it is not a professional look. It's not supposed to be
We want to demonstrate how anyone with some basic skills and scrap materials can build such a machine for next to nothing...

Bike compressor Mk 1.
What we did

So, we had an old bike, some scraps of steel and a small compressor. Wheels were taken off the bike, the sprocket was taken off the back wheel. As the compressor had a pulley for a belt and the bike had a chain, we had to either find a way to put a sprocket on the compressor or put an idler pulley in the middle and go from chain to belt. The pulley on the original compressor was Aluminium, so, we couldn't weld the steel sprocket to it, so it was decided to use some form of idler pulley and attach the chain sprocket to it. As we coudn't find a simple idler pulley, we used an alternator off an old car, took off the pulley, welded the sprocket to it and replaced the pulley/sprocket set-up and now we can pump air and also produce 12V power if we want to.  

The bike had gears front and back, so we kept the front gear changer, so we can change ratios, depending on the load - like if were pedalling up a hill.

At the back, we used the chain tensioner to keep tension on the chain and also to guide the chain over the rear support bar and to the alternator.
The tensioner is mounted to a bracket, that's welded to the rear support bar.

Similarly, we welded a couple of brackets to mount the alternator.
For the compressor, there are slots cut into the base plate for the mounting bolts. That allows the compressor to be slid back to tension the belt. 

The compressor we used initially was a little too small and we couldn't get the pressure up enough. Then this one was sourced (a friend had it laying around his farm and gave it to us), which is still quite small. It had a large pulley on it, so we found a smaller one and adapted it to fit. The gearing from alternator to compressor is now around 1:1. The gearing from crank to alternator is the maximum we could get, using the largest sprocket at the front and the smallest at the back to get maximum compressor revs. 

Front Gear Changer
As mentioned, the front gear changer has been retained in case of high pressures/loads. This one only has 2 gears and fairly short cranks. A 3 - gear model with longer cranks, as in a 24 inch or larger bike would be far better, as the longer cranks allow for more power produced by the peddaler, due to more leverage.

There are many ways of constructing this machine, depending on what materials are available. It may be just as easy to run the compressor straight off the chain, if a sprocket can be attached stright to the compressor, doing away with the intermediate idler pulley/sprocket.

Note: Most compressors use a splash oil system and normally require a minimum of around 600rpm for adequate oiling. As this set-up may not turn the compressor at 600rpm+, it is adviseable to overfill the oil in the compressor to make sure it keeps all the components lubricated.
Things to consider when building a bike powered compressor:
  • use the largest bike you can find - unless the person pedalling it is small
  • ensure the bike is mounted high enough for the pedals to clear the floor or frame when they are turning 
  • It is useful to use a bike with gears, as that can give added flexibility and make pedalling easier
  • use a fairly small pulley/sprocket at the compressor in order to get it turning at a reasonable speed and produce enough air to do the job. 
  • a 2 cylinder compressor is preferable to a single, as when pressures are elevated, the compression stroke load on the pedals is closed together and less jerky
  • If you can, add a flywheel to make the pedaling smoother. This could be mounted at the compressor or where ever it is easiest. It could be a weight off a weight bench or anything else that is heavy, round and pretty well balanced. 

How We can Help if you are looking to do a project in a third world country

If you want to build compressors like these for remote 3rd world villages and need old bikes - hundreds are thrown out in Australia all the time. Many are still good or just need basic repairs. If you want to do a project like this, we can do a charity drive to collect a container load of old bikes for you to work with, if you are going to purchase the pumps to be operated by them.

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