A rotary machine used for drilling the holes in combustible gases drainage. It is a twospeed, 150- to 250-rpm machine, drill-rod rotation being operated by a 6-hp (4.47-kW) motor. Traversing is done by a 2-hp (1.5-kW) motor, a pinion of which engages a toothed rack that runs the length of the drill frame. A forward drilling thrust of 4 st (3.6 t) is possible. The machine measures 10 ft (3 m) overall and weighs about 1,000 lb (454 kg). With an improved high-speed gearbox, 100 to 130 ft (30 to 40 m) of coal measures strata can be drilled in a shift.