A long, narrow pump designed for keeping a shaft dry during sinking operations. It is usually large enough to deal with 1,000 gal/min (3,780 L/min) from the greatest depth at which water will be encountered. A sinking pump must be slung from the surface and be fairly easy to raise and lower when shot firing takes place at the shaft bottom. Most are of the electrically driven centrifugal type and allow for additional stages to be fitted as the shaft depth increases. It may be suspended by a single-drum, worm-driven, capstan engine with a very slow speed.