• 16 parts
  • Checked September 2026

Parts of a Pneumatic System

A compressed-air system drawn as pictures, in the order the air flows.

Parts of a Pneumatic System

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
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Write the name of each numbered part.Answer key

  1. Inlet filter
  2. Compressor
  3. Electric motor
  4. Aftercooler
  5. Receiver
  6. Pressure switch
  7. Relief valve
  8. Drain
  9. Dryer
  10. Air line
  11. Filter
  12. Regulator
  13. Pressure gauge
  14. Lubricator
  15. Directional control valve
  16. Cylinder

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: a cylinder cut open, seal by seal

All 16 parts on the diagram

Show the list

Making and storing the air 10

  1. Inlet filter Protects the compressor from dust and other particles in the outside air.
  2. Compressor In this piston type, a piston squeezes the air in a cylinder. A bicycle pump does much the same.
  3. Electric motor Whatever drives a compressor is called its prime mover.
  4. Aftercooler As the air cools, some of its water vapor turns to liquid. The liquid can be drained off.
  5. Receiver It smooths out the pulses from the compressor. It holds enough air to meet a sudden demand.
  6. Pressure switch An electrical switch worked by pressure. It stops the compressor when the receiver is full and starts it again when the pressure falls.
  7. Relief valve A receiver is a pressure vessel, and has to have one.
  8. Drain The water is condensate. It is moisture squeezed out of the air as it is compressed and cooled.
  9. Dryer It removes more of the water vapor. The air that leaves an aftercooler still holds all it can.
  10. Air line Together the lines make up the distribution system. It takes the air to where it is needed.

Using the air 6

  1. Filter A clogged filter lets less pressure through. So it has to be looked at from time to time.
  2. Regulator Turning the knob changes the pressure. The pressure shows on the gauge below it.
  3. Pressure gauge It reads the outlet pressure. That is the pressure the regulator has been set to.
  4. Lubricator The oil is carried along in the air. It reaches the moving parts of the tool or cylinder.
  5. Directional control valve Used air is not piped back. It leaves through the valve's exhaust ports into the room.
  6. Cylinder Air let in at one end moves the piston and its rod. Air at the other end moves them back.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two of these use it: (1) US Navy, Fluid Power, NAVEDTRA 14105 (1990), full text at https://archive.org/details/fluidpower; (2) US Department of Energy and the Compressed Air Challenge, Improving Compressed Air System Performance: A Sourcebook for Industry, https://www.energy.gov/sites/prod/files/2014/05/f16/compressed_air_sourcebook.pdf (read from the Internet Archive copy of 2020-10-20); (3) Wikipedia, text only: Pneumatics, Pneumatic circuit, Air compressor, Compressed air dryer, Pneumatic cylinder and Pressure regulator. The detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's unit, nothing traced. Licence: own work

How it works

A basic pneumatic system in two drawings. The first makes, cools, stores and dries the compressed air; the second cleans it, sets its pressure and uses it to move a cylinder.

Read the full guide

Follow the air

Air enters through the inlet filter. The compressor, driven by the electric motor, squeezes it and sends it through the aftercooler into the receiver. A pressure switch stops the motor when the receiver is full. From the dryer an air line leads to the point of use: a filter, a regulator with its gauge and a lubricator. The directional control valve then sends the air to one end of the cylinder, and the used air escapes into the room.

  • Filter, regulator and lubricator are often bolted together as one unit, called an FRL.
  • Water is the enemy: the aftercooler, the receiver's drain, the dryer and the filter each take some out.

Questions and answers

What are the main components of a pneumatic system?

A compressor with its motor, a receiver to store the air, lines to carry it, a directional control valve and an actuator such as a cylinder. Around them sit the parts that treat the air: aftercooler, dryer, filters, a regulator and a lubricator.

What does the receiver do in a pneumatic system?

It stores compressed air. That lets the system meet a short peak in demand, evens out the pulses from a piston compressor and lets the compressor stop for a while when little air is being used.

What is an FRL unit?

A filter, a regulator and a lubricator joined in a row, fitted just before the tool or machine. The filter cleans the air, the regulator sets its pressure and the lubricator adds oil.

How is a pneumatic system different from a hydraulic one?

A pneumatic system works with compressed air, a hydraulic system with a liquid, usually oil. Oil is piped back to a reservoir after use. Used air is simply let out through the valve's exhaust port.

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