A Bit Of History; Introduction To Pneumatics; Generating Motion With Air - fischertechnik Profi Pneumatic II Manual De Instrucciones

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1. A bit of history

For thousands of years man has utilized air as a helpful resource, for
instance in order to make a fire with a bellows.
The Greek Ctesibios built the first compressed air cannons about 260 B.C.
While doing so, he used air which had been compressed into a cylinder
in addition to taut strings, and he was thus able to enormously extend
the range of the cannon. Therefore it's no wonder that the Greek word
"pneuma" – which translates into English as "air" – has lent its name
to this technique: "Pneumatics".
Compressed air-driven devices were utilized – above all in the construction
of roads and mining – with the beginning of the industrialization in the
19th century. Modern industry would be hard to image without pneumatics.
One finds pneumatically-driven machines and automatic machines
everywhere; for instance, they sort and mount various individual components
or package commodities.

2. Introduction to pneumatics

Certainly you have also noticed time and again that one can do quite a bit
with air. For instance, air can propel a windmill; with air one can inflate a
balloon or blow out a candle.
In the science of pneumatics it especially concerns generation motion with
air and transferring forces. With our Profi Pneumatic II construction kit we
especially would like to explain how pneumatic components function.
And for that purpose we will explain to you – step for step – the individual
components, and we will also illustrate how they function. In addition,
numerous examples of models are included in the construction kit, and they
explain how pneumatics are able to be utilized.

2.1 Generating motion with air

First of all, we will now generate a motion with air. And for this purpose we
will utilize a so-called pneumatic cylinder.
Tubing connections
Piston rod
Two different cylinders are included in the construction kit: A smaller cylinder
with a black piston rod, and a larger one with a blue piston rod. We will
speak about the difference later. We will utilize the cylinder with the blue
piston rod to start with.
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The piston rod is mobile, and sealed with respect to the cylinder wall. The
piston rod moves if one blows air into the cylinder through one of the two
tubing connections. The connection through which the piston rod travel is
marked with "A", while the connection for retraction is marked with "B".
There are also "single-acting", or "unidirectional cylinders". Their piston rod
can only be moved in one direction with air. One often utilizes a spring for
the motion in the other direction. The small cylinder with the black piston
rod is a unidirectional cylinder. It is located where the piston rod comes out
of the housing, and is not sealed.
Connection B
Gaskets
No gasket
Here the air escapes if one blows air into the cylinder through Connection B.
That's why its piston rod is able to be moved easier than the blue rod. You
will soon learn what this is good for.
Experiment:
Attach a piece of the blue tubing to Connection A, and blow strongly
into it. If you have enough breath, the piston rod will travel through.
Now, blow air through the tubing Connection B, and keep Connection
A closed with one finger at the same time.
B: Blow-in
What happens now?
Right, nothing happens. Can you explain to yourself why this is so?
Explanation:
The air in the power part of the cylinder is not able to escape. That's
why the piston rod does not move. And so when you blow air into
the first connection, the second connection always has to be open —
only then is the piston rod able to move. One says that the second
connection has to be "deaerated".
The cylinders which we have utilized, and in which the piston rod
can be moved as well as filled with air, are called "double-acting
cylinders".
Connection A:
Blow-in
A: Keep closed