This is the eighth of ten stories about how coal was mined in North Lanarkshire.
Coal is usually found deep in the ground and for centuries people have gone to great lengths to get it, using ingenuity and taking enormous risks.
Coal fuelled the industrial revolution. It was burned to heat homes, to power steam engines, to make iron. It could also be heated to extract gas and oil. In fact, coal gas used in most homes until North Sea gas was discovered. Scottish coal production grew from 2 million tonnes in 1800 to a peak of 42½ million in 1913.
Lanarkshire was home to Scotland’s biggest coalfield and at its peak in 1910 the county was home to about 200 coal mines.
Roof supports were used to prop up the strata above the miner’s head after coal was cut from the face. They reduced the risk of ‘bed separation’ which could cause roof collapse or the release of ‘firedamp’.
Supporting ‘packs’ were constructed from large stones. They were stacked floor to roof at regular intervals along the coal face. With the addition of girders, packs were also used to support the walls of roadways.
The photograph below shows a scene at Calderbank on the Monkland Canal in 1868. On the left hand side you can see pit props stacked-up ready for use:
Rigid supports were initially made from wood. A four foot long wooden prop supported 20 tons of weight whereas their steel equivalent could support 70 tons. ‘Bars’ were the horizontal sections that helped to spread the weight of the roof.
By the mid 1900s, yielding props became more widely used. These included hydraulic props which could be adjusted more easily and were hand operated.
The hydraulic ‘self-advancing’ system was particularly suited to continuous mining on ‘longwall’ faces. A series of props pushed forward a flexible conveyor, allowing the supports to advance after the machinery had passed.
This produced a prop-free front as they used cantilever bars for reaching across the conveyor. This supported the roof up to the face and could be raised or lowered as required.