Mining machine

A roadheader type mining machine comprising a self-propelled chassis, an elongate boom having a longitudinal axis, said boom being supported at one end by said chassis for powered positional adjustment with respect to said chassis, and a rotary cutting head provided on the other end of said boom, a transmission to drive said rotary cutting head and a final drive shaft located, coaxially with said boom longitudinal axis forming part of said transmission, a plurality of nozzles provided on said cutting head each to emit a water spray or jet, conveying conduits to supply water to said nozzles, said boom being of a two-part construction comprising an inner part that is non-rotatable about said boom longitudinal axis, that is supported from said one end on said chassis, and bearing means carried towards its other end for rotatably supporting an outer part that axially extends from said inner part, and power means carried by said non-rotatable part to rotate the rotatable part about said boom longitudinal axis;

• said cutting head being supported on said outer boom part and mounted rotatably with respect to said outer boom part;
• said final drive shaft being located at least partially within said rotatable part and provided with at least one radially extending cylinder having a closed inner end and an open outer end, a piston housed at least partially and in a reciprocable manner within said cylinder(s), with a variable volume, pressure-generating chamber defined between a radially inner end of said piston and a closed, inner end of its cylinder, a bearing ring carried by said rotatable part eccentrically with respect to said boom longitudinal axis, and with a radially outer end of each piston being in direct or indirect contact with an inner profile of said bearing ring such that upon rotation of said drive shaft, variation in radial distance of said inner profile from said boom longitudinal axis cause reciprocation of said piston(s), and a consequent pumping effect, with phased supply to said nozzles being controlled by suitable angular rotation of said rotatable part about said boom longitudinal axis to cause consequent rotation of the bearing ring.