Underground mining equipment. Used to shears coal from a long straight coal face (upto about 700 feet) by working back and forth across the face under a movable, hydraulic-jack roof-support system. The broken coal is transported by conveyor. Longwall machines can mine coal at the rate of 1,000 tons per shift. Mine locomotive, operating on tracks, is used to haul mine cars containing coal and other material, and to move personnel in specially designed "mantrip" cars. Large locomotives can haul more than 20 tons at a speed of about 10 miles per hour. Most mine locomotives run on electricity provided by a trolley wire; some are battery-powered.