Koepe

A Koepe system is a rope-hoisting arrangement in which two ropes, one attached to the cage or skip and one to the counterweight, run over a single large pulley called the Koepe drum. The pulley itself rotates to pull both ropes simultaneously, with friction between the ropes and the pulley providing the grip that transmits force. Unlike conventional drum winding, where ropes wrap around and unwind from a cylindrical mandrel, the Koepe system keeps rope lengths constant; as one side descends, the other ascends by the same amount.

The Koepe drum is typically 4 to 7 metres in diameter and has a ribbed or roped surface, often made of cast iron or fabricated steel, to increase friction contact. The ropes sit in these grooves and may be round or flat, typically 16 to 32 millimetres in diameter. A single motor and gearbox drive the drum through a main bearing assembly. The system requires precise rope tension and alignment, since uneven loading can cause slippage or rope climb.

Why Koepe instead of drum winding

Koepe hoists are preferred for deep shafts because they eliminate the need for the shaft to accommodate a drum that grows wider as rope layers up. In a 1000-metre shaft with conventional winding, the drum diameter can become prohibitively large. The Koepe system also reduces motor power demand during the lowering phase because the descending cage counterbalances the ascending one, and friction control rather than mechanical braking manages the load. However, the system depends entirely on friction between rope and pulley, so any oil film, water, or rope wear that reduces friction can cause dangerous slippage.

The system takes its name from Heinrich Koepe, a German engineer who developed the principle in the late 19th century. It became standard in European mining and is now the dominant method in deep hard-rock mines. The friction principle has made Koepe hoists central to ultra-deep operations: the world's deepest mine shafts, descending beyond 3000 metres, use Koepe winding almost exclusively.

Modern Koepe systems incorporate slip detection sensors and rope tension monitoring to prevent the friction failure mode. If either rope loses tension or the pulley surface degrades, warning systems alert operators before slippage occurs. Maintenance focuses on rope inspection, pulley surface condition, and alignment of the rope sheaves that guide each rope onto and off the drum.