Work on coaches, removing one set of gears (12)

I believe the answer is:

transmission

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'set of gears' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I can't see?

'work on coaches removing one' is the wordplay.
'work' becomes 'mission' (mission is a kind of work).
'on' is a charade indicator (letters next to each other).
'coaches' becomes 'trains' (coach can mean to train or educate).
'removing' is a deletion indicator.
'one' becomes 'i' (Roman numeral).
'trains' with 'i' taken out is 'trans'.
'mission' after 'trans' is 'TRANSMISSION'.

Can you help me to learn more?

(Other definitions for transmission that I've seen before include "A broadcast programme" , "The sending of a radio signal" .)

I've seen this clue in The Sunday Times and The Times.

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