The original coal plow; a heavy double-ended machine with fixed blades. Its length is 6- 1/2 ft (1.98 m); its height ranges from 14 to 31 in (35.6 to 78.7 cm). The depth of cut can be varied from 2 to 6 in (5.1 to 15.2 cm). The rapid plow has evolved from this relatively slow-moving machine.