A continuous miner, developed in the United States, for driving headings in medium or thick coal seams. It weighs about 26 st (23.6 t), and makes a cut 8-1/2 ft (2.6 m) wide, gathers the cut coal and loads it into cars or conveyor at a rate up to about 4 st/min (3.6 t/min). It can work in seam heights from 3 ft 8 in (1.1 m) up to about 10 ft (3 m). It consists, mainly, of a boom carrying the cutting head; the gathering head, and at the rear the jib support frame on which the jib can be slewed. The machine is operated by hydraulic motors.