Chapter 2 Fluid Power Systems 47
The compressed air next moves to the lubrica-
tor. This device adds a fine mist of oil to the air.
The oil lubricates any components through which
the air flows.
A directional control valve is the next com-
ponent in the basic pneumatic circuit. This valve
directs the air to the actuator, such as a piston in
a cylinder, causing the actuator to move. Existing
air from the other side of the piston is returned
through a system line to the same valve where
it is exhausted to the atmosphere. Shifting the
Compressor
Compressor
unit
Main
distribution
line
Directional
control
valve
Filter
Regulator
Exhaust
Workstation
Cylinder
(Actuator)
Flow control
valve
Workstation
pressure
gauge
Lubricator
Receiver
System
pressure
gauge
Prime
mover
Air intake
filter
Figure 2-23. The components of a basic pneumatic system that can provide
direction, fl ow, and pressure control for a cylinder.
Air
intake
filter
Intercooler
Drain
Second
stage
First
stage
Aftercooler
Coolant
out
Coolant
in
Separator-filter
Connection to
distribution lines
Air dryer
Receiver
Drain Drain
Figure 2-24. Airfl ow during compressor operation in a basic pneumatic system.
directional control valve directs airflow to the
opposite side of the piston, which reverses the
actuator. Air from the other side of the piston is
exhausted to the atmosphere through the valve.
See Figure 2-26.
When the actuator is fully extended or
retracted, it simply stops moving. The actuator also
stops moving when it encounters a load heavier
than it can move. This is possible because of the
compressibility characteristic of air and the overall
design of the pneumatic system.