fischertechnik COMPUTING ROBO TX ElectroPneumatic Manual page 5

COMPUTING
The air moves this cylinder in one direction only. It is returned to its initial position by the force of a
spring. Such cylinders are called "single acting cylinders".
Circuit diagram of single
Note:
acting cylinder
The connection you use to move out (extend) the piston is designated "A"; the piston is pulled back (re-
tracted) with the aid of a spring.
Air can be compressed
Anyone working with pneumatic equipment today should know something about the physical properties
of air. You can use a little test for this purpose:
Pull the red piston rod in the cylinder all the way out. Then hold connection A shut with your finger.
Now release the piston rod. What can you observe?
The piston rod is pulled back only a short distance by the spring.
Result:
The air in the cylinder is pressed together (compressed) preventing the piston rod from moving. The
more air compressed, the greater the air pressure in the cylinder. This pressure can be measured with a
pressure gage or also calculated. The unit of measure for pressure is
You can remember the following equation for this:
Pressure gage for
Pressure = force/area or p = F/A
measuring air pressure
From this equation you can see that the pressure depends on the force exerted on a round surface in the
cylinder.
Generating and storing compressed air – diaphragm pump as compressor
The diaphragm pump included in the construction set supplies the compressed air required for you to
control the individual models. In industrial circles this is known as the compressed air source.
Mode of operation:
Compressor
A diaphragm pump consists of two chambers
separated by a diaphragm (membrane). In one
chamber the resilient diaphragm is moved up
and down by a piston or cam. During the down-
ward stroke the diaphragm is pulled back and
air is pulled into the second chamber through
the inlet valve. When the piston moves up, the
diaphragm presses the air out of the pump head
Circuit diagram of
through the outlet valve.
compressed air source
Note:
The pressure generated by the compressor is approx. 0.7 to 0.8 bars. The diaphragm pump is mainte-
nance-free.
ROBO TX ElectroPneumatic
Inlet/outlet valve
Diaphragm
Cover
5
"bars" or "Pascals"
Piston
Crank drive
Cylinder