Drum motors power coal mining machine
Self-contained drum motors used as conveyor drive pulleys on high-wall mining machine allow quick, continuous harvesting of thin coal seams.
Conventional deep-pit mining with shafts, tunnels, and so forth is slow, expensive, and sometimes dangerous given the threat of cave-ins, fires, or explosions. Strip mining is efficient because it allows cutting wide swaths and harvesting thin seams of mined material. However, the overburden that must be removed to access deep deposits limits strip mining's economic feasibility, as do depth limitations for deposits that can be harvested.