‘Balls to the Wall’ Doesn’t Mean What You Think It Does
It all started with windmills
Balls to the wall has nothing to do with testicles. Neither does balls out.
Both expressions mean working at maximum effort or speed, and the balls in question are part of a device invented in the 17th century — the centrifugal governor.
Please, allow me to explain.
Centrifugal governors had some balls
James Watt designed the most widely known centrifugal governor in 1788 to prevent his steam engines from running out of control.
On the diagram below, the balls (labeled #3) are attached to lever arms linked to a vertical shaft. The horizontal shaft is the engine’s drive shaft.
As the horizontal shaft (on the right in the drawing) rotates, gears transfer the motion to the vertical shaft connected to the lever arms holding the balls.
When the engine spins more quickly, so does the vertical shaft, and centrifugal force causes the balls to move out and up.
