An air compressor squeezes air into a smaller space so it can be stored and used later. A motor turns a crank and rod that drive a piston inside a cylinder. Follow the air as it is drawn in, compressed and pushed into the tank.
An air compressor is a machine that squeezes air into a smaller space so it can be stored and used as a source of energy. This cutaway shows the common piston type, which works much like a bicycle pump: a piston slides in a cylinder, drawing air in on one stroke and forcing it out on the next.
The outside is only a finned lump with a tank beside it. What matters — the crank, the rod, the piston and the little one-way valves that decide whether air goes in or out — is all inside, and the cutaway lays it out where the eye can follow it.
The electric motor spins the crankshaft. The crank carries an off-centre pin, so as it goes round that pin traces a circle rather than simply rotating in place.
A connecting rod joins the crank pin to the piston. It converts the crank's circular motion into the piston's straight up-and-down travel — the same trick used in engines and bicycle pedals.
As the piston moves down, the space above it grows and the pressure there drops. That low pressure lifts the inlet reed valve and air is pushed in by the outside atmosphere.
On the way up the piston traps the air and shrinks the space it fills. Squeezing raises the pressure and the temperature, and the inlet reed is held shut while the discharge reed opens under the rising pressure.
The hot, pressurised air flows through the aftercooler, which sheds heat, then collects in the receiver tank. A pressure switch stops the motor when the tank is full and restarts it as the air is used.
It traps air in a cylinder and shrinks the space it occupies. On the down stroke air is drawn in; on the up stroke the piston squeezes that trapped air into a smaller volume, so its pressure rises.
They are one-way reed valves that react to pressure. On the intake stroke the low pressure in the cylinder lifts the inlet reed, and on the compression stroke the high pressure pushes the discharge reed open. No separate mechanism is needed.
Squeezing air heats it. The aftercooler is a coil or radiator that cools the compressed air on its way to the tank, which lets water vapour condense out and keeps the tank and tools cooler.
The receiver smooths the pulses from each piston stroke into a steady supply, and it lets the compressor run in longer, cooler bursts instead of starting and stopping for every little demand.
It watches the tank pressure. When the tank reaches the set pressure the switch cuts the motor, and when pressure drops it starts the motor again, so the compressor only runs when it needs to.