Here's Why 'Balls To The Wall' Is Actually An Engineering Expression

Screenshot via YouTube
Screenshot via YouTube

The expression “balls to the wall” has far less to do with male anatomy and quite possibly far more to do with the mechanical engineering genius of the steam engine.

Of course, almost nobody would know an exact reason for why the expression came to be so commonplace. You can kind of deduce it means that you’re going all-out, or perhaps giving it all you’ve got. The expression and that meaning actually likely originated with the steam engine; specifically the centrifugal governor used to keep things from blowing up.

Of course these origins are always contested, but his one seems pretty good. Oddly enough, I found what is the most likely explanation for the origin of “balls to the wall” at the end of a Real Engineering YouTube video about creating artificial gravity. The whole video is fascinating, but it’s the trivial fact at the end that stuck with me.

After checking in with my friends and colleagues to see if this was commonly known and realizing it wasn’t, I thought perhaps it was worth sharing.


The phrase “balls to the wall” may come with the centrifugal governor of a steam engine, which used spinning ball bearings to adjust a valve limiting the amount of steam entering the engine. As more fuel is put into the engine and more steam produced, the added pressure and centrifugal force of the spinning bearings pulls them outward toward the wall of their housing, subsequently activating a lever and a valve that limits the amount of steam.

It seems pretty simple but it’s also incredibly smart. Steam engines using fuels like coal and wood that often weren’t really measured in any meaningful manner would require some sort of management system, because if you were to shovel too much fuel in to the boiler and produce a lot of steam, you’re still limited by the mechanics of the rest of the engine.

If you want to hear Jay Leno explain it in much simpler terms, here it is:

Next time you put your balls to the wall you can feel a little smarter about it.


Edited to add that the exact origin of the expression may never be known, but hey, this one’s pretty good.

Reviews Editor, Jalopnik

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The governor expression is “balls out”. Aircraft is “balls to the (fire)wall”.

FWIW, a notch is a band of power drive on a Diesel-electric locomotive. To “take it up a notch” is to increase power and therefore speed. Top notch is notch 8, the highest notch on the power controller.