Steamboat-roll′ers.
（Coal-mining.) The large coal-breaking rollers at the mines. The lump coal is dropped through holes in the platform into a hopper, thence between a pair of heavy rollers known as steamboat-rollers, as they give the first rough breakage and produce the large size of coal known as steamboat coal. These rollers are armed with steel teeth, and revolve on parallel axes and toward each other. The coal falls on to an inclined screen known as the steamboat-screen (which see).
