Pivotal roof bolter and extendable rotatable protective canopy for mining machine

Claim 1

A pivotable protective canopy for an underground mining machine which has a work performing apparatus which is pivotable about a vertical axis in order to perform its work at different locations without moving the machine, which canopy is pivotable independent of but associable with the apparatus such that an operator can operate the apparatus while under protection of the canopy, comprising: a vertically extensible support mast including a first tubular section affixed to the mining machine, and a second tubular section slidably engaged with the first section; a fluid-pressure operated cylinder disposed interiorally of the tubular sections with one of its ends connected to the first section and its other end connected to the second section; and a canopy shield pivotably mounted on the second tubular section and cantileveredly extending therefrom; wherein the mast and cylinder are cooperatively operable to raise and lower the canopy shield with respect to the mine roof, and the sliding fit between the tubular mast sections is such that all the moment loads from the canopy shield are transferred through the mast sections to the mining machine, while the fluid cylinder incurs substantially only axial compressive load.