Abstract: An improved roof drill bit for use in mining operations in which a carbide insert is diametrically located in a cylindrical body and held on axial prongs in diametrically opposed quadrants of the body by a brazed connection; diverging axial holes for coolant are positioned in said prongs to open at the trailing side of the cutting edges of the carbide insert to flood the edges with coolant liquid and flush cuttings into the other quadrants. The coolant passages also pass near the brazed face of the insert to cool the body in this area and minimize softening of the braze. The bit shank and driving steel have cooperating axial grooves forming a passage for the coolant liquid to the bit body. The driving steel and bit body also have aligned chordal sides providing a passage for flushing drilling chips and fines toward the mouth of the hole.

Abstract: In a mining machine in which pick bits or point attack bits are held in a chain or wheel which moves next to coal or rock, a replaceable tool which is formed with a rear extension that is essentially cylindrical, that extension being split in circumferentially spaced slots so that portions will move resiliently in a radial direction. Outer radial projections interlock with annular surfaces or shoulders of a holding block to retain the tool in an operating position. The tool may be driven in or out of position without the need of clips or retaining rings. They may then rotate in the holding block to equalize wear on the tip.