Lego Pneumatic Air Compressor

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This page is about a Lego air compressor that I made for a project I'm working on.

The compressor is based on one I made previously using 1 Technic motor and 4 small pumps. In the first version, the pumps are arranged so that there's 2 layers of 2 pumps. Each layer has opposing pumps and the layers are a little over 90 degrees out of phase, giving a near continuous load for the motor.

This image shows the layout for the pumps and cranks.

Based on the same layout, I doubled up on the pumps and motors, giving 8 pumps and 2 motors. The image below is the completed compressor.

Sometimes the standard Lego air tanks are a little small, here, I've used a fizzy drinks bottle for extra air storage.

I used the plastic bottle to measure the output of the compressor. The bottle was full of water, the air goes into the bottle at the top and water is pushed out of the bottle via the blue tube (inside). From a standing start, the compressor pushes 375ml water out of the bottle in 1 minute... there is some pressure behind the water as the water tube has a small internal diameter (~2mm) and the water continues to flow out for a while after the compressor is switched off.
Click here to see a video of the water being pushed out (WMV, 11 secs, 1.13mb)

The compressor also works well as a bubbler.

Click here to see a video of the bubbles in a jug of water (WMV, 6 secs, 677kb)

The following images show some of the construction and workings of the compressor.

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