Definition
A basic mechanical device that changes the magnitude, direction, or speed of an applied force to perform work. The six classical simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw. All more complex mechanisms are combinations of these basic forms.
Plain English
A simple machine is one of a few basic tools — like a lever, pulley, or ramp — that lets you move or lift something with less effort, or in a different direction, than you could with your hands alone.
Context Anchor
Seen in basic aircraft systems and maintenance discussions, especially when explaining control linkages, pulleys, jacks, tools, and other mechanical parts.
Derivation
From Latin simplex, meaning 'single' or 'uncombined,' and machina, meaning 'device' or 'contrivance.' A simple machine is literally a single, uncombined device — the most basic building block from which more complex mechanisms are assembled.
Why Pilots Care
Almost every mechanical system on an aircraft — control cables and pulleys, jackscrews in trim systems, propeller blades acting as rotating wedges, wheel and axle assemblies — is built from simple machines. Recognizing them helps a pilot understand how a small cockpit input produces a large mechanical effect at the control surface.
Intuition Check
Simple does not mean weak, easy, or unimportant here. It means the device uses one basic mechanical principle, such as a lever or pulley, to change how force is applied.
Example Sentence 1
The pulleys that route the rudder cables through the fuselage are simple machines that change the direction of the pilot's foot input into a pull on the rudder horn.
Example Sentence 2
Pulleys acting as simple machines help route and tension the flight control cables without excessive force.