Abstract: A roof drill bit for drilling a bolt hole in a mine roof comprises a body defining a longitudinal axis of rotation and having an external periphery and a front face. A longitudinal fluid channel is formed in the external periphery for conducting a flow of flushing fluid to the front face. An imaginary longitudinal plane which contains the axis of rotation serves to bisect the front face into first and second sides. A cutting edge arrangement is defined by at least one cutting insert mounted on the body. The insert is positioned to be acted upon by the flow of flushing fluid. At least one support pad is mounted on the external periphery for balancing cutting forces acting on the drill bit. The cutting arrangement is asymmetrical with respect to the axis of rotation such that the cutting edge arrangement is disposed on one of the sides, and the other side is substantially free of the cutting edge arrangement.

Abstract: The rotor of the expander has axially extending slots containing vanes which reciprocate generally radially as the rotor turns since the rotor is eccentrically mounted in a casing. Vapor distribution ports extend from the base of each slot to the surface of the rotor forward of the slot. Axial passages for admitting pressurized, high temperature vapor from the ends of the rotor intersect with the vapor distribution ports at a point between the ends of the ports.Annular bearing elements are contained in the endwalls and lubricating oil is provided directly to them.