Trunnions definitions

trunnions

axles on which a drawbridge turned
Found on http://www.castles-of-britain.com/glossary.htm

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Trunnions

Pairs of cylindrical lugs formed one on each side near the point of balance of a cannon barrel to support it and to enable it to be elevated or depressed for firing at different ranges.
Found on https://www.encyclo.co.uk/local/22686

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