Roof drill bit

Claim 1

In a drill bit for rotary and percussion drilling of hard materials such as rock, coal, concrete and the like and of the type utilizing a drill body with a driving shank at one end and a cutting bit secured transversely of the body at the other end, that improvement which comprises: (a) a central body portion having a shank end and a cutting end, said shank end being circular in cross-section and having a first diametrical dimension, said cutting end having a second diametrical dimension in diametrically opposed enlarged quadrants larger than said first dimension, said ends joining at an annular shoulder, said cutting end having opposed flat portions tangential with circular opposed quadrants with a diameter substantially that of the first dimension, (b) a driving shank axially disposed on said body at the shank end and having a central coolant passage extending into said body, (c) support prongs extending from the cutting end of said body in said enlarged quadrants located substantially on opposite sides of perpendicular diameters of said central body but each extending past a common diameter to overlap, said central coolant passage terminating in coolant outlets on the shank end side of said shoulder open respectively to the other quadrants between said prongs, (d) said prongs being recessed at each digital end along one diameter of said body portion to receive a transverse cutting bit having axial cutting edges on opposite sides of the ends thereof away from the supporting prongs and axially in line with said coolant outlets.