Interactive mechanism · source-grounded teaching model
Atmosphere at work
Inspect the piston, beam and pump rod from different angles. Follow one power stroke and distinguish the force on the piston from the motion transmitted to the mine pump.
Piston. Condensation lowers pressure below the piston. Atmospheric pressure above it supplies the downward force.
The Newcomen power stroke
The problem below ground
Flooding limited the depth of mines. The Newcomen engine used a piston, rocking beam and pump rod to remove water. Its first successful installation near Dudley in 1712 drew on both scientific investigations and the skills of craftspeople working in wood, metal and masonry.
How the power stroke worked
Steam entered an open-topped cylinder beneath the piston. Injected cold water condensed the steam, lowering pressure inside the cylinder. Atmospheric pressure above the piston then pushed it downward. Through the rocking beam, that downward stroke raised the pump rod at the opposite end.
Explore the full motion cycle, including the return stroke →
Every part, in words
Piston. Condensation lowers pressure below the piston. Atmospheric pressure above it supplies the downward force.
Beam. The beam transfers the piston movement to a pump rod on the opposite side.
Pump rod. The opposite end rises during the power stroke. A real engine must then reset for its next stroke.
