In 1972, with the West Lyell Open Pit winding down, mining operations transferred underground. All development tunnelling until the end of the decade was carried out by a fleet of ten pneumatic Jumbos._x000D_
A decision was made in 1980 to purchase an electric-hydraulic Jumbo and a second was purchased in 1982. Their introduction changed the face of development at Mount Lyell._x000D_
Significant new demands were placed on main- tenance sections, particularly on electrical reticulation._x000D_
Subsequently, two further electric- hydraulic Jumbos were purchased from Agnew Mining in 1984, and successfully overhauled and commissioned. As well, two electric- nydraulic production drilling rigs have been purchased. Only one of the original pneumatic Jumbos remains in service.