from the GNU version of the Collaborative International Dictionary of English
- a carriage for heavy coast guns on which the gun is raised above the parapet for firing and upon discharge is lowered behind the parapet for protection. The standard type of disappearing carriage in the coast artillery of the United States army is the Buffington-Crozier carriage, in which the gun trunnions are secured at the upper and after ends of a pair of heavy levers, at the lower ends of which is attached a counterweight of lead. The levers are pivoted at their middle points, which are, with the top carriage, permitted restrained motion along the slightly inclined chassis rails. The counterweight is held in place by a pawl and ratchet. When the gun is loaded the pawl is released and the counterweight sinks, raising the gun to the firing position above the parapet. The recoil following the discharge returns the gun to the loading position, the counterweight rising until the pawl engages the ratchet.
Sorry, no etymologies found.