Background Information:
Mine Machines, Supporting the Roof Supporting the Roof Miners could not work the coal seams without a method of supporting the roof (the rocks above). Roof falls were a very common cause of injury and death underground. In early mines, and right through the twentieth century in some areas, a technique called pillar-and-stall would leave pillars of coal in place to keep the roof up. These also helped to prevent surface subsidence. Wooden pit-props (thick pieces of wood held in place with wedges) would support the rock strata close to where the coal was being worked. Roadways (tunnels used for travelling and transporting materials and coal) were supported using excavated rock built up into dry-stone walls, or using wooden props and beams and lined with thick planks of wood.
An image of a miner using a wooden prop to hold up the roof. Š NCM M E
A dry stone wall, and wooden props used to support the roof. Š Photograph from the Harold White Collection held at the National Coal Mining Museum for England
As the technology became available, hydraulic props started to be used at the coal face, while iron and steel girders and supports lined with corrugated metal sheets would be used in travelling roadways.
Hydraulic props and girders used to support. Š Queen's Printer and Controller of HMSO, 2013
Steel archways lined with corrugated metal in a travelling roadway. Š Queen's Printer and Controller of HMSO, 2013
Modern coal-faces make use of massive hydraulic props arranged in long lines at the face, which move forward as the face advances.
A line of hydraulic props used at a modern coal face. Š Queen's Printer and Controller of HMSO, 2013
In modern roadways, a technique of bolting the roof is used to hold the rock in place. A pattern of 2.7 metre roof bolts are drilled into the rock and held in place with resin. Using bolts such as these, there is no need for any other form of support, as they redistribute the stresses from the weight of the rocks above.
Roof bolting and mesh used in a modern roadway. Š Unknown
Find out more about machines used to support the roof, on site at the Museum in the Coal Interface Gallery and on the underground tour.