Jennmar Australia now offers the LITTLE JOHN MINE PROP for use as standing support. The LITTLE JOHN can be configured to be a stiff or yielding system depending on mine requirements. The LITTLE JOHN is currently available in 45-tonne capacity.
The LITTLE JOHN is constructed with an inner pipe sliding inside an outer pipe creating a telescoping effect that allows for extension of the prop from a collapsed position used for transport into the mine.
Each prop is fitted with an end plate, designed for optimum mine performance, to distribute the load to the mine roof and floor. The top and bottom plate can be custom designed for mine requirements.
The prop can be extended to the roof height with the aid of a setting tool. Controlled yielding is provided by a split piece of pipe, with inner nubs, that is clamped to the smaller diameter section of the prop.
The graphical results (see below) were obtained at the NIOSH Safety Structures Testing Laboratory. The first set of results was performed while collapsing the prop in a vertical displacement.
These graphs illustrate 75 and 150 mm yield displacement. As in the BIG JOHN, the LITTLE JOHN can be custom configured to provide whatever amount of yield displacement is desired