Abstract: A center vacuum rotary drill bit including a rotary drill bit body, an insert and an insert spacer assembly. The rotary drill bit body includes a top working surface having a slot extending transversely across the top working surface. The slot includes a first sidewall, an opposite second sidewall and a generally horizontal bottom surface extending between the first sidewall and the second sidewall. The insert includes a pair of oppositely facing generally parallel side surfaces, a pair of oppositely facing generally parallel end surfaces extending between and interconnecting the side surfaces, a pair of oppositely inclined top surfaces extending between and interconnecting the side and end pairs of surfaces, and a bottom surface extending transversely to and interconnecting the side and end pairs of surfaces. The insert spacer assembly includes a shim and a spacer bar.

Abstract: A center vacuum rotary drill bit including a rotary drill bit body, an insert and an insert spacer assembly. The rotary drill bit body includes a top working surface having a slot extending transversely across the top working surface. The slot includes a first sidewall, an opposite second sidewall and a generally horizontal bottom surface extending between the first sidewall and the second sidewall. The insert includes a pair of oppositely facing generally parallel side surfaces, a pair of oppositely facing generally parallel end surfaces extending between and interconnecting the side surfaces, a pair of oppositely inclined top surfaces extending between and interconnecting the side and end pairs of surfaces, and a bottom surface extending transversely to and interconnecting the side and end pairs of surfaces. The insert spacer assembly includes a shim and a spacer bar.

Abstract: A center vacuum rotary drill bit including a drill bit body having a top working surface. Formed within the top working surface is a slot having disposed therein an insert positioned within a shim within the slot. The insert includes a pair of oppositely facing generally parallel side surfaces, a pair of oppositely facing generally parallel end surfaces extending between and interconnecting said side surfaces, a pair of oppositely inclined top surfaces extending between and interconnecting said side and end pairs of surfaces, and a bottom surface having a concave depression formed therein. The bottom surface extends transversely to and interconnects the side and end pairs of surfaces. A support bar including a convex top surface is disposed within the slot between the insert bottom surface and the slot such that the convex top surface supports the concave depression of the insert. In a preferred embodiment, the modulus of elasticity of the support bar is greater than the modulus of elasticity of the shim.

Abstract: A trenching tool assembly with dual indexing capabilities includes a block formed with a tool shank bore and a cutter bit having a shank which is insertable into the tool shank bore. The shank includes a polygonal portion which is preferably a hex. An indexing washer is formed with a central opening shaped to engage the polygonal section of the cutter bit shank and to prevent relative rotation therebetween. The indexing washer engages the tool block in any one of a number of fixed positions. To change the angle of attack of the cutter bit, the indexing washer is disengaged from the tool block and cutter bit shank. The indexing washer and cutter bit shank can be indexed as a unit or independently of one another.

Abstract: A cutting bit for mounting in a block mount. The cutting bit including a working head and a shank depending therefrom. The shank includes a recess formed within at least one side portion thereof. The block mount includes two matching half members secured on opposing sides of a rotating disc. A slot extends perpendicularly across at least one of the half members to receive the shank in a wedge like fit. Formed within the slot is a pin for mating engagement with the recess.

Abstract: An excavating tooth for use in connection with an earth drilling auger includes a main body portion terminating in a working end and a shank extending upwardly from the main body portion. A plurality of tungsten carbide inserts are embedded in the working end of the tooth and project outwardly therefrom. During drilling operations, the carbide inserts engage the earth and chisel away rock and other material which is subsequently conveyed to the surface by the fight structure of the auger. The inserts are inclined forwardly with respect to the plane of the shank to enable the inserts to withstand greater loads than before. In the preferred embodiment, the insert has a generally cylindrical proximal end embedded in the working end of the auger tooth and a distal end including forward and rearward inclined surfaces terminating in a transverse cutting edge.