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PneumADDic II • Masterpiece 4 155

common in earth moving machines such as backhoes and bulldozers. However, probably
the most common example of pneumatics in action is the tire on an automobile.Tires
maintain their shape by storing pressurized air provided by an compressor.
Figure 1.1 shows the two types of pneumatic pumps available from LEGO: large
pumps and small pumps.

Figure 1.1 LEGO Pneumatic Pumps

Pressurized Air Outlets

These pneumatic pumps have one pneumatic connector where air is forced out when
the pump is compressed.This pressurized air is directed into a piston, which can be
forced to expand (push the air out) and contract (suck the air in).The piston’s movement,
be it expansion or contraction, is used to deliver the power that drives a pneumatic
device. Figure 1.2 shows the two kinds of LEGO pneumatic pistons available today.

Figure 1.2 LEGO Pneumatic Pistons

Contract Pressure Inlets

Expand Pressure Inlets

Figure 1.3 shows the function of a pneumatic switch that has a pressure inlet and two
inlet/outlet ports that connect to a pneumatic piston. When the lever of the pneumatic
switch is in the center, the pressure inlet is shut off, as are the two ports that connect to
the piston. When the lever is flipped to the left, any pressure present on the left port is
released to the atmosphere, and the pressure from the pressure inlet is forced out the right
port into the piston. When the lever is flipped to the right, the pressure that was present
at the right port is released to the atmosphere, and the pressure from the pressure inlet is
forced out the left port into the piston.