Man engine

A man engine is a mechanism of reciprocating ladders and stationary platforms installed in mines to assist the miners’ journeys to and from the working levels. It was invented in Germany in the 19th century and was a prominent feature of tin and copper mines in Cornwall until the beginning of the twentieth.

Operation



In the Cornish examples the motive power was provided by waterwheels, or one of the mine's beam engines. Originally operating without a flywheel, this offered a reciprocating motion of, typically, twelve to fifteen feet (three to five metres). The engine would be linked to a series of beams – known as "rods" – fastened together and reaching to the bottom of the mineshaft. Small platforms would be attached to the rods at the same distance apart as the engine stroke. Fixed platforms were built onto the shaft walls, spaced to coincide with the top and bottom positions of each of the moving platforms. In a common variation a pair of rods was used, with one on its upstroke as the other descended. The miner hopped from one to the other, rather that waiting at a fixed rest, as they changed direction. Counterweights – large boxes filled with stones attached through "see-sawing" horizontal beams – were installed in order to avoid the full weight of the shaft and men bearing on the engine beam. In the deepest mines, which could sink to more than 350 fathoms (640 metres), extra counterweights were provided in side-shafts at regular intervals.

To go up or down, the miner would step onto the travelling platform and allow himself to be carried to the next fixed platform, where he would step off and wait. At the end of the next stroke the next moving platform would line up and he could step onto it and repeat the process. Although the footholds were often small, grab handles were fitted above each one. Miners may ascend and descend at the same time: the pause at the changeover point is made long enough for two men to change places.

Safety



The miners took to these devices without hesitation as their pay was not calculated until they had reached their underground workplace. Contemporary safety studies concluded that, although intrinsically dangerous, the use of a man engine was in practice safer than climbing long ladders: it was less risky to be carried up at the end of a hard shift than to climb a ladder and risk falling because of exhaustion. In some mines, particularly in Germany, wedges or collars placed just above close-fitting rollers, or chains, were installed to limit any drop should a breakage occur.

Levant mine accident

In the afternoon of 20 October 1919 an accident occurred on the man engine at the Levant Mine, St Just, Cornwall. More than 100 miners were on the engine being drawn to the surface when a metal bracket at the top of the rod broke. The heavy timbers crashed down the shaft, carrying the side platforms with them, and thirty-one men lost their lives. The man engine was not replaced and the lowest levels of the mine were abandoned.

History

The earliest known examples of this device were from the silver mining area of the Harz mountains, Germany, where they were driven by cranks connected to water wheels, although bucket hoists using the same method of operation had been used in Swedish iron mines since the 17th century. They appear to have evolved from an informal modification to the beam pumps, where the miners stuck spikes into the wooden pump rods to get themselves carried up the shaft. As beam pumps were universal in deep mines, it was a then simple development to make proper platforms to carry the miners. The first formal engine was installed in 1833 at a mine at Clausthal, Lower Saxony, where inspector Wilhelm Albert and manager Georg Dörell (1793–1854) fastened foot platforms and hand-holds to adjacent, reciprocating pump rods, using a waterwheel-driven pump put out of use when a new drainage adit was made at a lower level. The 1837 man engine at Grube Samson in Sankt Andreasberg in the same region is still in use, although converted from water to electric power in 1922.

The device was introduced to Cornwall in 1842, following the award of a premium for the best design, by the Royal Cornwall Polytechnic Society. The winner, Michael Loam, built one for the proprietors of the Tresavean Mine, in Lanner near Redruth. He used a double-rod design, driven by a waterwheel. The miners' journey time (in either direction) was reduced from about an hour to twenty-four minutes and output per shift increased by one fifth. More than a dozen examples were installed in Cornish mines by the end of the century, but these were usually of the single-rod type, which was perceived as safer in use.

When cable operated winding gear became available the man engines continued in use, particularly in cases where the mineshaft was not truly vertical and winding engines drawing suspended cages could not be used: with the provision of a few well-place rollers, and “fend offs” mounted on trunnions, the rods could reach the bottom of a shaft even at a substantial deviation from the vertical. Economics also played a part: the rods needed for pumping could be used for this extra function at little increased cost. Even when skips or “kibbles” were used in such shafts, (running on “skipways”) the tipping motion would make them impractical for carrying men.

From http://en.wikipedia.org/