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A Primer on Lego Pneumatics |
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| Lego Pneumatic
Elements There are only 7 elements in Lego Pneumatics as shown in the
accompanying picture. 1. Pneumatic cylinders These come in 2 sizes, large and small, which look different in shape but function in the same way. |
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| Most of the time you will be using
the large cylinders as they are more powerful. Each cylinder has two ports, one at the top
and one at the bottom.When air is let in through the bottom port, the piston is pushed
outwards (extended). When air is let in through the top port, the piston is pulled
(retracted) into the cylinder. That's all that the pneumatic cylinder can do - simply a
to-and-fro motion. 2. Pneumatic pumps There are 2 types, which differ in size and method of operation. The large pump is spring loaded and meant to be worked by hand. The smaller pump has no spring and is meant to be driven by a motor as an air compressor. 3. Pneumatic valve switch This is the key element in pneumatic control. Each valve has 3 ports - which can serve
as inlets or outlets depending on the circuit. There is an additional outlet for the
exhaust air but it is inaccessible. The pneumatic switch can take up one of 3 positions.
The central position is neutral. By flipping the switch to one extreme or the other, the
air flow will be directed to the appropriate part of the circuit, as shown in the
following diagrams.
Be warned that the pneumatic switches are rather stiff to operate and requires some force to make them flip over. This is not a problem as normally the switches are moved by hand. But later on, we're going to use linkages to flip the switches automatically, that's when the resistance will be felt. 4. T - junction tube This is used when you want your pneumatic lines to branch out to several points. 5. Pneumatic tubing These are flexible plastic tubing or hose, which come in 3 colors - light grey, dark grey and blue. My own convention is to use the blue colored tubing for the air supply line. However, they are hard to come by. 6. Air Tank This is a blue cylindrical plastic tank which acts to store air under pressure so that
your model will continue to run even after you stopped pumping the hand pump. It is not an
essential item. People have used various substitutes such as plastic bottles, etc. These are short dark-gray plastic tubes meant to be used with flex cables. But you can use them to join the pneumatic tubing to extend their length. Great when you have inadvertently cut your pneumatic tubing too short. You can also make use of the long decorative plastic tubes in the Mindstorms sets. These tubes can be clipped down to the Technic beams or plates to hold the pneumatic tubing in place. That's all there is to the pneumatic elements. Individually, they are of no use. They have to be connected together in different types of pneumatic circuits to be useful. |
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Basic pneumatic circuit
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Typical pneumatic applications
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