What is "relievers"

Usage examples of "relievers".

Other waggons held drag-chains, crooked-sponges, relievers, bricoles, wad-hooks, sabot-bracers, and hand-spikes.

Beside the guns were the tools of the artillerymen's trade: drag-chains, relievers, rammers, sponges, buckets, searchers, rammers, wormhooks, portfires and handspikes.