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United States Patent 3,693,722
Brown September 26, 1972

FINE GRADING DEVICE FOR RUBBER TIRE ROAD GRADER

Abstract

A grading blade and parallel rotary auger are supported on an auxiliary frame transversely with respect to a grader vehicle from which the frame is supported with the auger being connected to the blade for unitary pivotal movement about a pivot point on the frame between the front of the blade and the rear of the auger in general vertical alignment with the cutting edge of the blade so that the height of the auger can be pivotally adjusted by hydraulic cylinder means with respect to the cutting edge of the blade for differing soil conditions by pivoting the auger and blade with there being a negligible vertical displacement of the cutting edge of the blade; an automatically operable control means actuates hydraulic cylinders supporting the auxiliary frame from the vehicle in response to signals from a guide line extending along the path of movement of the vehicle for maintaining the cutting edge of the blade at a given elevation with respect to the guide line regardless of the height of the auger with respect to the cutting edge of the blade as adjusted by the operator for differing soil conditions.


Inventors: Brown; Robert L. (Chesapeake, VA)
Assignee: Brohigbu, Ltd. (Norfolk, VA)
Appl. No.: 05/062,917
Filed: August 11, 1970


Current U.S. Class: 172/4.5 ; 172/72; 172/785; 37/382; 37/907
Current International Class: E02F 3/76 (20060101); E02f 003/76 (); A01b 049/02 (); E02f 003/12 ()
Field of Search: 172/785,779,72,71,4.5,784 37/108

References Cited

U.S. Patent Documents
3490539 January 1970 Hilmes et al.
3568778 March 1971 Swisher et al.
1883404 October 1932 Ronning
3423859 January 1969 Swisher et al.
Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Pellegrino; Stephen C.

Claims



I claim:

1. A highly accurate grading means supported on a main attachment frame supported on a power driven vehicle having a main frame and drive means for movement along a path to be graded, said grading means comprising elongated blade means having a lower cutting edge supported by pivotal support means connected to said main attachment frame, said blade means extending substantially transverse to the path of travel of said vehicle, linkage connecting means connected to and extending from said blade means, elongated rotary earth cutting auger means supported by and connected to said linkage connecting means having an axis of rotation parallel to said blade means positioned for rotation immediately forward of said blade means, control means for moving said auxiliary support frame vertically for maintaining the lower edge of the blade at a desired elevation, said pivotal support means supporting said blade means, said linkage connecting means and said rotary auger means for unitary pivotal movement about a pivot axis positioned forward of the front surface of said blade means between the front surface of said blade means and the axis of rotation of said rotary auger and in substantial vertical alignment with the lower cutting edge of said blade, and actuator means for unitarily pivoting said auger and said blade about said pivot axis for adjusting the height of said auger with respect to the surface being graded without any substantial change in the elevation of the lower cutting edge of said blade with respect to the surface being graded.

2. The invention of claim 1 wherein said earth-cutting auger includes a plurality of radially extending digger teeth and a spiral blade.

3. The invention of claim 2 wherein said pivotal support means supporting said blade means and rotary auger for unitary movement includes first and second vertically extending spaced pivot support plate means extending downwardly from said attachment frame along the rear side of said blade, pivot shoe means extending forwardly from the lower edge of each of said pivot support plate means through a respective aperture in said blade and terminating forwardly of the forward surface of said blade, a pivot pin means connecting the forward end of each of said pivot shoes to bracket plates extending forwardly from said blade so that said blade and auger are pivotally supported by said pin for pivotal movement by said actuator means.

4. The invention of claim 1 wherein said pivotal support means supporting said blade means and rotary auger for unitary movement includes first and second vertically extending spaced pivot support plate means extending downwardly from said attachment frame along the rear side of said blade, pivot shoe means extending forwardly from the lower edge of each of said pivot support plate means through a respective aperture in said blade and terminating forwardly of the forward surface of said blade, a pivot pin means connecting the forward end of each of said pivot shoes to bracket plates extending forwardly from said blade so that said blade and auger are pivotally supported by said pivot pin for pivotal movement by said actuator means.

5. The invention of claim 2 wherein said control means for moving said attachment frame comprises first and second hydraulic cylinders connected between the main frame of the vehicle and said attachment frame whereby actuation of said cylinders serves to vertically move said blade and said auger.

6. The invention of claim 5 wherein said linkage connecting means upon which said rotary auger means is mounted for rotation comprises first and second auger support plates each respectively pivotally connected intermediate its end to each end of said blade for pivotal movement about an axis transverse to the path of movement of said vehicle with said auger being mounted for rotation on one end of said plates and adjustably extendable and lockable adjustment means connecting said blade and the other ends of said first and second auger support plates for fixedly locking the relative position of said auger and said blade in a desired position of adjustment.

7. The invention of claim 6 wherein said attachment frame means includes a transversely extending main cross piece, a semi-circular arcuate frame member connected adjacent each end of said transversely extending main cross piece and having its arcuate portion extending forwardly therefrom, draw bar means extending forwardly from a pivotal connection connecting said draw bar means to the middle of said main cross piece, pivotal connection means connecting the forward end of said draw bar to said vehicle, and connecting means connecting said forwardly extending portion of said arcuate frame to said draw bar means with said first and second hydraulic cylinders extending from said vehicle being connected to said arcuate frame for supporting said arcuate frame.

8. The invention of claim 7 wherein said means connecting said arcuate frame to said draw bar comprises removable pin means which, when removed, permits pivotal movement of said draw bar with respect to said arcuate frame and said transversely extending main cross piece to reduce the overall width of the grading means by permitting movement of the auger and blade to a canted position relative to the axis of the supporting vehicle for movement to a different location.

9. The invention of claim 8 wherein said draw bar comprises a forward portion consisting of first and second parallel frame members, a connector frame removably connected to the forward end of said parallel frame members and a pair of rear frame components extending parallelly from the upper surface of said forward parallel frame components for connection to said transversely extending main cross piece.

10. The invention of claim 1 wherein said actuator means for unitarily pivoting said auger and said blade about said pivot axis includes first and second hydraulic cylinder means connected between said attachment frame and said blade so that actuation of said first and second cylinder means serves to unitarily pivot said blade, said linkage connecting means and said rotary auger.

11. The invention of claim 10 wherein said pivotal support means supporting said blade means and rotary auger for unitary movement includes first and second vertically extending spaced pivot support plate means extending downwardly from said attachment frame along the rear side of said blade, pivot shoe means extending forwardly from the lower edge of each of said pivot support plate means through a respective aperture in said blade and terminating forwardly of the forward surface of said blade, a pivot pin means connecting the forward end of each of said pivot shoes to bracket plates extending forwardly from said blade so that said blade and auger are pivotally supported by said pivot pin for pivotal movement by said actuator means.

12. The invention of claim 11 wherein said control means for moving said attachment frame comprises first and second hydraulic cylinders connected between the main frame of the vehicle and said attachment frame whereby actuation of said cylinders serves to vertically move said blade and said auger unitarily.

13. The invention of claim 12 wherein said linkage connecting means upon which said rotary auger means is mounted for rotation comprises first and second auger support plates each respectively pivotally connected intermediate its ends to each end of said blade for pivotal movement about an axis transverse to the path of movement of said vehicle with said auger being mounted for rotation on one end of said plates and adjustably extendable and lockable threaded adjustment means connecting said blade and the other ends of said first and second auger support plates for fixedly locking the relative position of said auger and said blade in a desired position of adjustment.

14. The invention of claim 13 wherein said frame means includes a transversely extending main cross piece, a semi-circular arcuate frame member connected adjacent each end of said transversely extending main cross piece and having its arcuate portion extending forwardly therefrom, draw bar means extending forwardly from a pivotal connection connecting said draw bar means to the middle of said main cross piece, pivotal connection means connecting the forward end of said draw bar to said vehicle, and connecting means connecting forwardly extending portion of said arcuate frame to said draw bar means with said first and second hydraulic cylinders extending from said vehicle being connected to said arcuate frame for supporting said arcuate frame.
Description



The subject invention is directed to the field of earth moving equipment and is specifically directed to a highly accurate fine grading device connectable for use on a conventional road grader.

The need for highly accurate grading means for obtaining a graded surface with a minimum amount of variation from a desired height has resulted in numerous devices directed toward this need.

Unfortunately, the prior known systems have frequently failed to provide adequate accuracy in maintaining a desired grade level notwithstanding the fact that such machines have been extremely complicated and consequently expensive to manufacture and maintain. Moreover, many of the prior known systems have been in the form of unitary machines comprising a driven support vehicle with the grading means fixed to the vehicle and supported therefrom. Consequently, such devices have been much more expensive than would be the case if the grading means per se could be connected to a conventional vehicle such as a conventional grader.

The obvious desirability of being able to mount a grading attachment on a conventional grader is complicated by the large number of conventional graders of different sizes, models and manufacturers which are presently in use.

Therefore, there has been an unmet need prior to this invention for a highly accurate fine grading device capable of providing a fine graded surface within minimum tolerances but also being capable of use with conventional currently available grading equipment.

It is the object of this invention to provide a new and improved fine grading device capable of high grading accuracy and also capable of being mounted on a conventional road grading machine.

Obtainment of the object of this invention has been achieved through the provision of a grading device which can be attached to a conventional road grader and which includes a blade extending transversely across the path of movement of the grader with a rotary auger being closely spaced forwardly of the blade. The rotary auger is continuously driven by hydraulic motor means for removing the major portion of the earth in front of the blade and depositing it alongside the work path as the grader moves along the surface being graded. In fact, optimum grading accuracy is obtained by having the blade remove only a small percentage of the total earth being removed during the passage of the device along the work path.

The auger and the blade are unitarily connected together on an auxiliary support frame for vertical adjustment by automatically controlled hydraulic cylinder means which is controlled by a guide line stretched along each or either side of the work path. In practice, the lower or cutting edge of the blade should always be agiven fixed distance below the guide line. This fixed distance is maintained by constant monitoring of the guide line by conventional means as the machine moves along the work path and consequent control of the cylinders supporting the blade and auger. However, it has been observed that optimum grading accuracy can best be obtained in different soil conditions by varying the height of the auger with respect to the cutting edge of the blade. This height variation is manually maintained by the operator of the device in accordance with the nature of the soil through which the blade and auger are being moved. However, this adjustment of the height of the auger with respect to the blade should be made with a minimum amount of vertical displacement of the lower edge of the blade in order to maintain a fixed vertical distance between the lower edge of the blade and the guide line. In other words, the vertical distance between the lower edge of the auger and the lower edge of the blade which determines the amount of bite that the auger takes of the earth in the work path as it is slowly advanced along the work path should be adjustable with a minimum variation in the height of the blade cutting edge.

Obtainment of a substantial degree of auger adjustment with little or no blade vertical height variation is achieved by this invention through the use of a unitary connection between the blade and the auger so that they are supported by a unitary framework with this framework being mounted for pivotal movement about an axis spaced substantially in vertical alignment with the cutting (lower) edge of the blade forward of the front face of the blade between the blade and the auger. The pivot axis is also in substantial horizontal alignment with the axis of rotation of the auger. Consequently, this critical location of the pivot axis provides a substantial vertical displacement of the auger with respect to the blade when the blade and auger are unitarily pivoted with practically no vertical displacement of the blade occurring.

The entire inventive assembly can be attached to conventional existing control arms of a conventional road grader by the automatically controlled double-acting hydraulic cylinders connected to ball and socket connectors on the grader. The front of the auxiliary frame is also connected to the grader by conventional ball and socket arrangement. The ball and socket connectors are those that are currently employed for supporting a conventional blade frame on road graders presently in use. Consequently, the fine grading attachment comprising the subject matter of this invention is interchangeable with the conventional blade assembly on the presently known road graders. However, the device could also be supported on a specially designed vehicle if desired.

Improved results obtained by this invention are due largely to the fact that the invention effectively enables the elimination of all slippage of the rear drive wheels of the grader which are passing over the surface being graded. Such slippage or spinning of the wheels creates indentations in the finished surface and causes the entire machine to settle downwardly so suddenly that it is difficult for the automatic control device system to react in time to maintain a finished surface that is smooth and at the correct elevation. The adjustably mounted rotary auger preceding the cutting edge of the blade is vertically adjustably mounted so that the cutting edge of the blade removes only a small amount of material from the surface being graded and the forward driving power conveyed through the drive wheels is consequently substantially reduced. Moreover, the auger bite can be adjusted to compensate for variations in density or hardness of the soil to prevent spinning of the wheels as the grader moves from one type of soil to another. Since the auger removes the major portion of the soil being removed along the work path and this removal is effected entirely by virtue of rotation of the auger, the resistance to forward movement of the grader is much less than would be the case if the blade were the sole device for removing the soil above the grade level.

It is essential that the grader be capable of advancing at a very slow rate of speed so that the automatic control device for maintaining the height of the blade at the desired elevation have sufficient reaction time in which to make corrective movements. This slow speed is accomplished by using a very low travel gear or other slow drive devices on the grader and high power requirements of the hydraulic motor for driving the auger are met by adding an auxiliary high capacity hydraulic pump to the motor grader, power take-off shaft.

Other objects and advantages of the subject invention will be better understood from the following specification and claims when read in light of the accompanying drawings in which:

FIG. 1 is a perspective view of the preferred embodiment of the inventive concept;

FIG. 2 is a side elevational view of the preferred embodiment with portions removed for clarity;

FIG. 3 is a plan view of the preferred embodiment;

FIG. 4 is a sectional view taken along lines 4--4 of FIG. 3;

FIG. 5 is a sectional view taken along lines 5--5 of FIG. 4;

FIG. 6 is a sectional view taken along lines 6--6 of FIG. 3; and

FIG. 7 is a sectional view taken along lines 7--7 of FIG. 3.

Turning first to FIG. 2, it will be seen that the preferred embodiment of the invention, which is generally designated 10, is associated with a conventional road grader 11 having drive wheels 12 and steering control wheels 13 on an elongated main frame member 14 for supporting work attachments depending therefrom. Additionally, the grader is provided with a drive motor for driving wheels 12 and the various engine accessories. The preferred embodiment 10 of the invention is suspended from the main frame 14 of the conventional grader by ball and socket connections 15 attached to control arms 16 (only one of which is shown in FIG. 2) which extend along each side of frame 14. Arms 16 are normally employed for supporting a conventional grader blade.

The preferred embodiment includes a main attachment frame generally designated F and which includes a horizontal draw bar 20, an end connector frame member 22 (FIG. 6), a semi-circular arcuate frame member 24 (FIG. 4) and a transversely extending main cross piece 26 (FIGS. 1 and 4) which provides support for the other components of the grading attachment.

Draw bar 20 comprises a forward portion consisting of first and second parallel channel or box frame members 28 and 30 (FIG. 1) which have a connector plate 32 welded to their forward ends. A second connector plate 34 is welded to the rearmost end of the end connector frame 22 and the connector plates 32 and 34 are bolted together to provide a fixed rigid connection between the elements 28, 30 and 22. The purpose of providing the detachable connection between these elements is to reduce the overall size to enable loading of the attachment upon a truck for transportation. Otherwise the length of the components would exceed most statutory width lengths and could not be legally transported in many states. Additionally, a plurality of connector frame members 22 having different length and height dimensions can be provided for enabling connection of the device to different road graders in which the positions of the female pivot socket 82 will vary. Moreover, the size of the male connector ball 80 can also be varied in order to accommodate various female pivot sockets of different sizes. Consequently, the device will be interchangeably mountable upon a wide variety of road graders having different height female pivot sockets and various frame lengths.

The rearmost portion of the draw bar 20 is formed of a pair of identical frame components 36 and 38 connected on their forward ends by a curved plate 40 (FIG. 6) and which are connected to the upper surface of the frame components 28 and 30 respectively to extend rearwardly for pivotal connection to the transverse main cross piece 26. This pivotal connection of components 36 and 38 to cross piece 26 is enabled by means of a pivot pin 42 mounted in a bracket 44 extending from the rearmost ends of members 36 and 38 and a pair of bracket plates 46 and 48 welded to the front surface of cross piece 26. Pin 42 extends through bracket 44 and plates 46, 48 as shown in FIG. 6.

A brace frame 50 is attached to the upper surface frame components 28 and 30 and has a top plate 52 connected to the rear of the components 36, 38. A curved plate 54 completes a curved opening through the brace frame through which arcuate frame 24 extends. A pin 56 is provided to extend downwardly through a hole in plate 52 and through the arcuate frame 24 to lock the arcuate frame 24 in position. However, removal of pin 56 from the arcuate frame 24 allows frame 24 etc. to pivot about pin 42 by virtue of the fact that the ends of frame 24 are weldingly connected to each end of the main transverse frame component 26.

First and second curved vertically extending pivot support plates 58 and 60 are respectively welded to the extreme ends of the main transverse frame component 26 and respectively have horizontal arms 58' and 60' embracingly curving around the rear portion of the arcuate frame member 24 as shown in FIG. 1. The horizontal arms 58' and 60' are welded to the external surface of the curved frame 24 as shown in FIG. 4.

Plates 58 and 60 extend downwardly to terminate at their lowermost ends in pivot shoe means 62 and 64 (FIG. 3) respectively welded to their lower ends. The pivot shoe means 62 and 64 respectively support identical bearing sleeves 66 (FIGS. 7 and 6) which provide a pivotal support for a blade assembly to be discussed hereinafter.

It should be noted at this point that the main attachment or auxiliary frame F consists of a unitary structure comprising the arcuate frame 24, the main transverse member 26, draw bar elements 36, 38, 28 and 30 and the pivot support plates 58 and 60. Additional strength and rigidity is provided the frame F by means of a rearwardly extending brace plate 70 extending rearwardly from the main transverse frame component 26 adjacent the entire middle thereof, gusset plates 72 and 74 respectively welded adjacent each end of member 26 and to the pivot support plates 58 and 60 as best shown in FIG. 3 and a pair of rod brace members 76 welded to the lower ends of the pivot support plates 58 and 60 and to plate 70 on the middle portion of member 26 as clearly shown in FIG. 3. Additionally, a forwardly extending linear brace plate 78 extends forwardly from the main transverse frame component 26 along the front face thereof and along the entire length thereof as best shown in FIG. 1.

Support for the forwardmost end of the frame F is provided by a pivot ball type male connector member 80 attached to the forward end of the connector frame 22 and receivable in a conventional female pivot socket 82 on the grader frame as best shown in FIGS. 2 and 6. The rear portion of the frame F is supported by ball and socket connectors on support bracket plates 84 and 86 extending upwardly from the upper surface of arcuate frame 24 and connected to piston rods 88 and 90 of control cylinders 92 and 94 which have ball socket connectors 15 attached to their uppermost ends. The ball and socket connectors 15 are connected to the control arms 16 of the grader as has been noted previously.

Bearing sleeves 66 which are welded to the forward ends of pivot shoes 62 and 64 provide support for a scraper blade 100 which extends perpendicular to the path of travel of the grader 11. Support for blade 100 is provided by a pair of pivot pins 102 which are each mounted on the forward end of and between a pair of bracket plates 104. Bracket plates 104 are attached to blade 100 and extend forwardly from the front face 101 of blade 100 as shown in FIG. 7. It should be noted that the pivot pins 102 are located in substantial vertical alignment with the lower edge of the blade 100. It should also be noted that the pivot shoe members 62 and 64 each extend forwardly between two of the plates 104 through respective openings in blade 100 to terminate in front of the forward surface 101 of the blade in the manner illustrated by pivot shoe 64 in FIGS. 6 and 7. It is this construction which provides for pivotal movement of the blade 100 about the axes of pins 102.

A rotary auger 106 is supported for rotation in bearings mounted in auger support plates 108 and 110 which are respectively pivotally connected to blade 100 by pins 114 and 116 extending from brackets mounted adjacent the top of the front face 101 at each end of the blade 100. The purpose of the pins 114 and 116 is to provide for initial pivotal adjustment of the auger support plates 108 and 110 and auger 106 supported thereon with respect to the blade 100. Following such adjustment, the support plates 108 and 110 and the supported auger 106 are locked in fixed relationship with respect to the blade 100.

FIGS. 6 and 7 illustrate the manner in which the auger 106 is initially adjustably positioned with respect to the blade 100. Specifically, the rear side of blade 100 is provided with a pair of rearwardly extending adjustment brackets 118 and 119 (FIG. 3) which are welded to the blade adjacent each end thereof above a rear brace plate 120 extending along the length of blade 100 on the rear face of the blade. Identical rod and sleeve adjustment means are pivotally connected to the brackets 118 and 119 by a pivot pin 124 and to the upper or rearmost end of the support plates 108, 110 by a pivot pin 126.

Adjustment of the two adjustment means 122 connecting each end of blade 100 to the auger support plates 108, 110 serves to pivot the auger support plates 110 and 108 about the pins 114 and 116 fixed to the ends of blade 100. Consequently, the position of the auger 106 is adjusted with request to blade 100 is an obvious manner as shown in FIG. 7. Once the desired adjustment has been achieved, no further adjustment is normally necessary and blade 100, auger support plates 108, 110 and auger 106 constitute a unitary structure. Additional threaded rod members 134 and 136 (FIG. 3) extending between the blade and the auger support plates 108 are provided for locking the blade and auger in fixed relative position following the adjustment thereof.

It is emphasized that the blade 100, auger support plates 108, 110 and auger 106 are consequently fixedly connected to each other to constitute a unitary structure. This unitary structure is pivotally supported by coaxial pins 102 fixed to blade 100 and pivotally extending through sleeves 66 on the forward ends of pivot shoes 64 and 62 as was previously discussed. Therefore, the auger 106 and the blade 100 which are connected by the elements 108, 110 and 122 pivot about the axis of pins 102.

Pivotal movement of the unitary blade-auger structure 100, 106 etc. for lifting or lowering the auger is enabled by first and second unit adjusting places 138 and 140 which are welded to the rear side of the blade 100 adjacent back brace plates 141 as best shown in FIG. 3. The upper ends of plates 138 and 140 are respectively connected to cylinder 138' and 140' which are pivotally connected to frame members 141 extending from arcuate frame 24 as shown in FIG. 1.

Auger 106 is driven by a hydraulic drive motor 142 (FIGS. 1 and 3) through a step-down transmission 144 connected to the auger support plate 108. The output of step-down transmission 144 is to a drive sprocket in a chain housing 146 on the right side of support plate 108 as viewed in FIG. 4. A chain 148 is driven by the output from the transmission 144 and extends about a sprocket on an auger drive shaft 150 extending through auger support plate 108. Consequently, rotary movement is imparted to the auger 106 from the motor 142. A separate identical hydraulic motor could be mounted on the plate 110 if such should be desired; however, it has been found that a single high power motor 142 is adequate for driving the auger. However, a great deal of power is required for driving the auger and it is necessary to provide an auxiliary hydraulic pump to be driven by the grader motor. The hose connections etc. for operating the hydraulic motor 142 are not shown in the drawings since such would merely serve to clutter the drawing and obscure the true invention.

Auger 106 comprises a spiral plate 160 extending outwardly from a heavy body cylinder 162 along the entire length of the body cylinder. Additionally, the auger is provided with a plurality of intermediate digger teeth 164 positioned intermediate the adjacent convolutions of the spiral blade 160 which extend outwardly radially approximately one or two inches (depending upon soil conditions) beyond the outer periphery of blade 160 for dislodging rocks etc. as the auger is rotated in the direction of the arrow in FIG. 6. A shield 166 extends forwardly from the upper edge of the blade 100 to prevent such material from being thrown rearwardly toward the operator by the rotation of the auger 106.

A control means support beam 180 extends outwardly from a hollow box channel 182 connected to the top of the main transverse member 26. Such a beam 180 extends from each side of the device and is adjustably retained by clamping means 186 associated with the channel 182 in an obvious manner. Conventional line detecting switch means, sensors or tracers 190 are supported on the ends of the beam 180 for detecting a conventional wire or line 192 extending along each side of the path of movement of the machine. The detecting means 190 etc. is conventional and forms no part of this invention. However, it should be understood that the detecting means 190 etc. provides electric over hydraulic signals to the supporting cylinders 92 and 94 for raising and lowering the blade to maintain the lower or cutting edge of the blade 100 a fixed vertical distance below the guide lines 192.

It has been found that optimum accuracy in grading can be obtained by adjusting the pivotal position of the auger 106 and the blade 100 by actuating the pivot cylinders 138' and 140' for pivoting the plates 138 and 140 along with the blade 100 and auger 106. Such adjustment is normally made by the operator as the device goes through varying types of soil. However, while this adjustment causes a substantial variation in the height of auger 106, substantially no vertical variation of the lower or cutting edge of the blade 100 is caused by such pivotal adjustment as is evidenced from inspection of FIG. 7 of the drawings which illustrates two different positions of the blade and the auger as would be caused by actuation of cylinders 138' and 140' to vary the height of the auger 106. Such adjustment serves to vary the bite taken by the auger as it is moved forwardly through the soil 200 being graded. It has been found that optimum grading accuracy can easily be obtained with the auger 106 removing the majority of the soil and only a small percentage of the soil being removed by blade 100. Normally, the best results are obtained with the lowermost portion of the digger teeth 164 on auger 106 being spaced approximately even with or slightly above the lower or cutting head edge of blade 100. Therefore, the subject device serves to provide an extremely accurate grade as the grader 11 is moved slowly forward with the auger 106 rotating in the direction of the arrow in FIG. 2. Auger 106 removes the majority of the earth being graded and blade 100 provides the finishing accuracy. Grader 11 is normally driven at a very slow speed of approximately one mile per hour and auger 106 is rotated at approximately 80 rpm. The necessary slow forward speed of movement requires the use of an extra low gear in the grader.

It should be understood that numerous modifications of this invention will undoubtedly occur to those skilled in the art; however, the invention is to be limited solely by the appended claims.

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