spare part
noun
- duplicate of a part of a machine kept in case needed in repair
Wiktionary
noun
- A component of any manufactured goods, kept in reserve to replace one that fails; a spare.
“It is extremely difficult to obtain spare parts from abroad, and these are manufactured in the shops [workshops].”
“As for the rest, Steward says: " I suspect probably only 40 to 50 may have a future on the rails, and the others will be componentised. As with all industries, recycling is a very big thing. There's a lot of value in the spare parts."”