From movie Titanic(1997), you can find a transcript here
Ismay: So you've not yet lit the last four boilers?
Smith: No, I don't see the need. We are making excellent time.
Ismay: The press knows the size of Titanic. Now I want them to marvel at her speed. We must give them something new to print! This maiden voyage of Titanic must make headlines!
Smith: Mr. Ismay, I would prefer not to push the engines until they've been properly run in.
Ismay: Of course, I'm just a passenger. I leave it to your good offices to decide what's best. But what a glorious end to your final crossing if we were to get to New York on Tuesday night and surprise them all! Make the morning papers. Retire with a bang, eh E.J.?
Ismay: [Smith nods reluctantly] Good man.
What's the meaning of run in here? From thefreedictionary, run in can be translated into two meanings:
- A quarrel or an argument.
- Printing Matter added to a text.
Of course, neither is suitable for the context. So how to explain "run in" here?
Best Answer
The break-in or mechanical run-in is a standard procedure for a brand new engine, like those on the Titanic.
I think (and someone more familiar could confirm) that "run in" is the British term. It means the same thing as the Americanism "break in". To break something in is to take something brand new and use it in such a way that it reaches a higher capacity for performance. You might break in a new pair of leather boots so they fit you better and don't cause blisters when you walk, or the engines on a brand new ship.
I found "run in" in the Oxford dictionaries, confirming my theory that it's a Britishism used almost exactly the same way as the Americanism "break in" with respect to engines and mechanical things. The Brits also use "break in" the way Americans do for other (non-mechanical) things.