Continuing with the post-election catchup, back in late October (a veritable lifetime ago), @JLaBua sent on Twitter a link to a use of “spanner” by NPR’s Nina Totenberg. Speaking of the confirmation of now-Supreme Court Justice Amy Coney Barrett, she said: Senate Majority Leader “Mitch McConnell is a master strategist, and they’re still on track, but their execution has to be perfect. They can’t have many more GOP senators get COVID-19. It could really throw a spanner in their plans.”
It was interesting but I felt I had said all I had to say about the word so didn’t plan a new post. But the very next day my brand new spin bike arrived. When I looked at the included tools, what should I find but:

Interestingly, a third tool was included, which was labeled a “wrench.”

What is the difference between a spanner and a wrench? That turns out to be the title of a post on the (British) Wonkee Donkee Tools website:
Spanners vs Wrench

In the UK, a spanner is a fixed-profile hand tool which fits or removes a fastening by turning a nut or bolt and a wrench is a similar tool but turns non-fastening components, for example, a pipe (or Stillson) wrench which is used to turn and manipulate pipes.

The term ‘wrench’ is also used to describe a spanner-type tool that has an adjustable profile size. These tools are also known as ‘adjustable spanners’ or ‘monkey wrenches.’”
In the USA, the word ‘wrench’ is used almost entirely instead of the word ‘spanner,’ but, because the USA and European markets are linked, the terms ‘wrench’ and ‘spanner’ often appear interchangeable in Britain.
Perhaps that clears things up a bit. (Perhaps not.) I will note, in conclusion, that the company that made the bike, Sunny Health & Fitness, says on its website, “We carry only the finest exercise and health equipment from top manufacturers in Taiwan and China.” And the font on the tool package indeed has a characteristic Chinese look. Talk about throwing a spanner into the semantic works.
How about the slightly different meaning in British English where “spanner” (via the superclass of “tool” 🙂 ) also means “someone of limited intelligence”.
“That Boris Johnson is a bit of a spanner.”
Does it equate with AmEnglish “Wrench” ? Could an American say “Yeah, that guy is a bit of a wrench” and have it mean the same ?
Nope, we just have “tool,” not individual tools.
That’s what I thought the post was going to be about 😆
What would Americans call a monkey wrench? https://en.wikipedia.org/wiki/Monkey_wrench
Monkey wrench.
Most often, we would I would just call it an adjustable spanner. Surely Americans also use the expression, “put a spanner in the works”? It’s such a common expression.
Not common over here, Anthony. If you look at my earlier post (linked to in this one), I go into it.
My experience in teaching Asian graduate students in my friendly local university suggested that they mostly had learned British English, but since I taught writing in petroleum engineering–which is highly US-centric–I spent a lot of time on idioms. I suspect a Chinese bike company could be expected to follow British tradition.
In my opinion the essential property of a wrench is that it has gripping jaws. I have a pipe wrench that is not adjustable.