Hoist (mining)

Modern hoists are normally powered using electric motors, historically with direct current drives utilizing Ward Leonard control machines and later solid-state converters (thyristors), although modern large hoists use alternating current drives that are variable frequency controlled.

[1] Drum hoists are mounted on concrete slabs within a hoistroom, the hoisting ropes run from the drum, up to the top of the headframe, over a sheave wheel and down where they connect to the conveyance (cage or skip).

Drum hoists can continue to operate if the shaft bottom gets flooded and less shaft depth is required below the loading pocket, unlike friction hoists where such flooding could cover the tail ropes and so on.

[4] Friction hoists are mounted on the ground above the mine shaft, or at the top of the headframe.

Friction hoists, unlike drum hoists, can and normally do use multiple ropes giving them a larger payload capacity, however since they require a larger safety factor, they are impractical for very deep shafts.

Friction hoists can not operate at normal speeds if the shaft bottom is flooded and water reaches the tail ropes.

The configuration was developed by Robert Blair for use with extremely deep mine shafts in South Africa.