? a wheel for a gun-carriage.

A small solid wooden wheel or roller; spec. Nautical one of those on which the carriages of ships' guns were formerly mounted.

Esp. of constructed objects, parts of the body, etc., as after-limb, after-truck, etc. Now rare, except in sense affix 1a(a)(ii).

a sturdy dished wheel used on gun carriages; a similar wheel formerly used on motor vehicles.