Router Bit

1. Technical Field

This invention relates to earthmoving equipment and, more particularly, to a quick-change replaceable router bit assembly mounted on the vertical walls of the leading edge or leading corner of the scraper bowl.

2. Background Art

Side cutting router bits mounted at corners where the earth-engaging blade meets the scraper bowl of earthmoving equipment are particularly useful in defining a sharp and clean boundary line when earth is removed during operation. The ground-engaging portion of the router bit is susceptible to a high degree of wear due to rocks and other hard material. Since the router bits experience different wear rates, individual replaceable router bits have been found to be particularly useful. Exemplary replaceable router bits are shown in Gilbertson U.S. Pat. No. 3,088,232, Lutz U.S. Pat. No. 3,465,833, Smith U.S. Pat. No. 3,994,084 and Hood et al U.S. Pat. No. 3,839,806.

It has been the practice to provide single-piece router bits which are detachably secured to the bowl of the earth-working machine by nut and bolt assemblies. In most instances the router bit itself is directly secured to the bowl by bolts extending through both the bit and the bowl. Other router bits are adjustable. For example, in U.S. Pat. No. 3,994,084 to Smith, a slidable router bit can be adjusted to accommodate the wear which takes place along the forward edge of the tool. Additional support straps across the bit and secured to the side of the bowl are helpful for retention. Even these bits are secured to the bowl by a plurality of nut and bolt assemblies.

A significant amount of material is rendered useless with single-piece and double-piece router bits known to the prior art after the ground-engaging portion of the tool wears away.

The present invention is directed to overcoming one or more of the problems as set forth above.

In one aspect of the invention, the amount of material which is rendered useless is minimized by providing a router bit assembly of a two-piece construction. The first piece of the router bit assembly is a holder which is detachably mounted on the bowl at the corners of the blade where the blade meets the vertical walls of the bowl. The second piece of the router bit assembly includes a metal bit having a configuration adapted to be received within the holder. The bit is inserted within the holder to form the router bit assembly which is then coupled and secured to the vertical side wall of the bowl of the earth-working equipment at the leading edge or the leading corner of the ground-engaging blade. When the bit is worn away, the holder is detached from the bowl and the bit is removed therefrom and a new blade is inserted within the holder. Then the router bit assembly with the new bit therein is reattached to the vertical side wall of the bowl.

The use of a two-piece router bit assembly advantageously reduces the required amount of material which heretofore has been uselessly discarded after the cutting portion of the prior art bit wore away.

FIG. 1 is a perspective view of a bowl of an earth-working scraper having two router bit assemblies incorporating an embodiment of the present invention;

FIG. 2 is a side view of one of the router bit assemblies coupled to the bowl of the earthmoving equipment;

FIG. 3 is a cross-sectional view of the router bit assembly taken along the line 3--3 of FIG. 2; and

FIG. 4 is a perspective, exploded view of the router bit assembly of an embodiment of the present invention.

Referring to FIG. 1, a tractor (not shown) draws a bowl 10 of an earthmoving scraper 12 forward in the direction of the arrows so that an earth-engaging blade 14 engages the ground, which ground is then deposited in the bowl 10 for transport or removal. The end portions of the blade 14 are adjacent a pair of vertical side walls 20 and 24 of the bowl. One router bit assembly 18 is secured to the vertical side walls 20 of bowl 10 and a similar router bit assembly 22 is secured to the vertical side wall 24 of said bowl 10. The router bit assemblies 18,22 define the side boundaries of the blade 14 and cut a sharp edge into the earth during operation.

Referring to FIGS. 2-4, the construction of the router bit assembly 22 attached to a corner portion 25 of the vertical wall 24 of bowl 10 will now be explained, it being understood that the configuration of the router bit assembly 18 is identical to that of router bit assembly 22.

The router bit assembly 22 includes a holder 26 having spaced-apart bifurcated sides 28 and 30 which define a slot 32 (FIG. 4) therebetween. The sides 28 and 30 are retained in spaced-apart relationship by integrally formed spacer portions 34 and 36. The integrally formed spacer portion 34 defines bit-engaging surfaces 38 and 40 within slot 32 and integrally formed spacer portion 36 defines bit-engaging surfaces 38' and 40' for retaining a bit 42, and will be discussed in greater detail below.

Bit 42 includes body portion 44 defined by parallel side walls 43,45 and end walls 46 and 48. Ground-engaging forward walls or surfaces 50 and 52 taper forwardly from end walls 46 and 48, respectively, to form a leading point 54. A rear edge 56 of bit 42 is contoured to fit the selected configuration of a leading edge 58 of the corner 25 of the vertical side wall 24, as best seen in FIG. 2.

The body portion 44 of the bit 42 has laterally extending flanges 60 and 62 that project outwardly from the end walls 46 and 48, respectively. The flanges 60 and 62 overhang the end walls 46,48 and have holder-engaging surfaces 64 and 64', respectively, which abut surfaces 38 and 38' on spacer portions 34,36 when the bit 42 is received within the slot 32 in the holder 26. At the same time, the end walls 46,48 of the bit 42 about against inwardly facing surfaces 40,40' on said spacer portions 34,36.

When bit 42 is received within the slot 32 in the holder 26 and the rear edge 56 of the bit 42 engages the leading edge 58 of the corner 25 of the bowl wall 24, bolts 66 and 68 are inserted through aligned holes 70 and 72 in sides 28,30 in the holder 26 and through holes 73 in vertical bowl wall 24 whereupon nuts 74 on the bolts will retain the holder 26 in straddling relationship to the corner 25 of vertical bowl wall 24. Any known fasteners 66,68 could be used, such as pins, or the like. The bit 42 is thereby captured between the leading edge 58 of corner 25 and the holder 26 by the flanges 60 and 62 on the bit engaging with the bit-engaging surfaces 38, 38', 40 and 40' on the integrally-formed spacer portions 34 and 36 on the holder 26.

When the bit 42 is worn away to a point approaching the leading edges 75 of the holder 26, bolts 66 and 68 are removed to detach the router bit assembly from the vertical wall 24 of the bowl 10. The router bit 42 is withdrawn from the holder 26 through the rear of the slot 32. A new bit 42 is then inserted within holder 26 which is then reattached to the vertical side wall 24 of bowl 10 by bolts 66,68 and nuts 74.

The mounting of the holder 26 in straddling relationship to the leading edge of the wall of the bowl 10, with the rear wall 56 of the bit 42 bearing against the leading edge 58 of the bowl, reduces the shear loads on the pins or bolts. That is, the forces on the bit 42 are mostly transmitted through the bit 42 and directly into the wall of the bowl. The holder 26 and bolts 66,68 serve more to stabilize the bit 42 and to prevent bending or laying over of the bit relative to wall 24 of the bowl 10. The main load on the bit 42 is passed directly to the wall and not to the bolts 66,68, holder 26 and then to the wall.