US3303589A

US3303589A - Automatic control device for road graders and the like

Info

Publication number: US3303589A
Application number: US362740A
Authority: US
Inventors: Rivinius Theodore
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-04-27
Filing date: 1964-04-27
Publication date: 1967-02-14
Anticipated expiration: 1984-02-14

Description

T. RIVINIUS Feb. 14, 1967 AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE Filed April 27, 1964 5 Sheets-Sheet 1 INVENTOR 77/600026 mil/All;

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T. RIVINIUS Feb. 14, 1967 AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE 5 Sheets-Sheet 2 Filed April 27, 1964 INVENTOR. filaboxz P/VM/ll/s Feb. 14, 1967 r. mvmlus 3,303,589

AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE Filed April 27, 1964 5 Sheets-Sheet 4 INVENTOR. m 73 200026 Flu M10: Y

1 I 9 \0 Q z/am Feb. 14, 1967 T. RlVlNlUS 3,303,589

AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE Filed April 27, 1964 5 Sheets-Sheet 5 United States Iatent O 3,303,5s9 AUTQMATIC CONTROL DEVICE FQR ROAD GRADERS AND THE LIKE Theodore Rivinius, 1011 Ave. B W., Bismarck, N. Dak. 58501 Filed Apr. 27, 1964, Ser. No. 362,740 18 Claims. (Cl. 37-156) This is a continuation-in-part of my successively mutu ally, co-pending applications for Automatic Control Device, Serial No. 154,288, originally filed November 22, 1961, now abandoned; Serial No. 223,290, filed Septemher 7, 1962, now abandoned; and Serial No. 270,473, filed April 3, 1963, co-pending at the time of the filing of this present application.

The present invention has relation to an automatic control device for road graders and the like and more particularly to a device which, when attached to certain controls of a road grader or other earth working machine, will automatically maintain the earth working blade of such a machine at a selectively predetermined slope with respect to the horizontal.

In a device made according to the present invention, a horizon sensing case or pendulum case is mounted with respect to a frame member carrying the earth working blade in such a manner that the angular relationship between the vertical axis of the horizon sensing case with respect to a plane parallel with the longitudinal axis of the road grader and encompassing the lower working edge of the earth working blade can be selectively varied at will. A pendulum is pivotally mounted in the horizon sensing or pendulum case in operational alignment with a pair of switches in said case, the arrangement being such that the pendulum will always tend to move toward vertical alignment and one or the other of the switches being activated to closed or on position by the pendulum whenever it is not in vertical alignment. These switches when closed or on activate first and second control circuits, respectively. Each of these circuits, when thus activated, operate on the normal controls of the grader or the like to tend to move the earth working blade in direction to cause its respective closed switch to move out of contact with the pendulum and hence to an open or off position.

Road graders typical of the devices on which the apparatus of the present invention will prove useful can include a circle frame or the like to which the earth working blade is fixedly mounted. Such a circle frame will lie in a plane parallel to the lower working edge of the earth working blade. This circle frame can typically be mounted on a draw bar linkage which is pivotally mounted at a forward end thereof to the main frame of the grader.-

By rotating the circle frame about its axis, the angular relationship of the earth working blade with respect to the longitudinal axis of the main frame of the grader can be changed as desired. Assuming that the slope of the area which is to be graded is other than horizontal, then the plane of the circle frame can not be horizontal either. As the circle frame is rotated to change the angle of attack of the earth working blade, the angle of the plane of the circle frame will have to be changed in order to maintain the lower edge of the earth working blade in the desired plane. To accomplish this, an upright support plate is pivotally mounted on an upright support axis to a main mounting bracket reference arm in such a manner that the upright support axis is maintained at all times in parallel relationship to the axis of the circle frame and perpendicular to the longitudinal axis of the machine. The horizon sensing case is then supported in fixed angular relationship to the upright support plate so that any deviation from the preselected angle by the plane of the circle frame and the corresponding 3,363,589 Patented Fete. 14, 1957 upright support axis as the circle frame is rotated will institute a corrective signal within the sensing case to return these parts to the preselected angle.

The horizon sensing case is pivotally mounted to the upright support plate on an axis aligned with the longitudinal axis of the machine. The angular relationship of this case to the support plate is controlled by a motor mounted on the draw bar linkage, and by controlling this relationship, the slope being formed by the earth working blade with respect to the horizontal is controlled.

The control circuits and the controls operated by those circuits can be simple on-off arrangements whereby the angle of the earth working blade can be continuously changed until the corresponding switch in the pendulum case goes to the off condition. Such arrangements have been satisfactorily used. Hydraulic valving is particularly adaptable to this kind of usage. However, changes in the ambient temperature can effect the flow properties of the hydraulic fluids involved, and this factor and other factors can result in sluggish operation of the controls or in a hunting operation whereby the machine is overcontrolled so that the earth working blade goes too far, thus causing the opposite switch to be activated and an opposite correction to be called for.

It has been found that these difiiculties can be overcome by providing that the control circuitry and controls, while a particular switch is in the activated or on condition, operate intermittently to cause corrections to the circle frame plane angle in small increments. Such controls can be either hydraulic or electrical, but electrical controls are particularly effective when used in this manner.

In the drawings,

FIG. 1 is a side elevational view of a road grader having a control device made according to the present invention installed thereon;

FIG. 2 is an enlarged fragmentary perspective view of certain of essential elements of the grader and of the grader control of the invention as seen from above the right rear quadrant of the grader;

FIG. 3 is an enlarged horizontal sectional view taken on the line 33 in FIG. 1;

FIG. 4 is an enlarged vertical sectional view taken on line 44 in FIG. 3;

FIG. 5 is a vertical sectional view taken on the line 5-5 in FIG. 4;

FIG. 6 is a greatly enlarged fragmentary perspective view of certain of the elements of FIG. 2 as seen from above the right front quadrant of the machine; and

FIG. 7 is a schematic representation of the control circuitry of this form of the invention.

A road grader 15, which is conventionally made, includes an elongated main frame 16 and is mounted on a plurality of wheels 17. The grader is powered with an engine 18 through suitable mechanism (not shown). A cab 19 is positioned on the main frame of the grader and houses the grader controls indicated generally at 20.

An earth working grader blade 21 is mounted through suitable brackets 22 to a circle frame 23. The circle frame is rigidly attached to an A-frame or draw bar linkage 26 which in turn is pivotally connected to the main frame 16 of the grader as at 177 in any usual or preferred manner. The earth working blade 21 may be rotated with the circle frame 23 about the axis 25 of the circle frame. In this way, the blade can be angled to any desired position.

The depth of the earth working blade 21 is controlled through conventional power lift mechanism (not shown) mounted in a housing 24. The mechanism drives a pair of rock shafts 27 which are each rotatably mounted on suitable support bearings 28 attached to main frame 16. Each rock shaft 27 has a lever 29 fixedly attached thereto. A link 34) is pivotally mounted as at 31 to each of the levers 29 and extends downwardly to engage at 31a a bracket 32 which rotat-ably supports the circle frame and forms a part of the A-frame 26.

A first rock shaft control lever or handle 33 is pivotally mounted as at 35 to housing 24 and operates a control rod 36 which operates mechanism to control the rotational position of left rock shaft 27 and its attached lever 29. A second rock shaft control lever or handle 34 is pivotally mounted as at 37 to housing 24 and operates a control rod 38 which operates mechanism to control the rotational position of right rock shaft 27 and its attached lever 29. See FIGS. 1 and 2. Each lever 29, acting through its associated link 30, will raise or lower one side of the bracket 32 and the circle frame and consequently raise or lower one end of the grader blade 21. Other grader control levers are provided for the other grader operations.

The structure just described is conventional and is used on a large number of road graders commercially available at the present time.

An automatic control device made according to the present invention includes a horizon sensing unit 40 which has a main mounting bracket or reference arm 42 ivotally mounted on a cross beam 41. This cross beam 41 is fixedly attached between the two legs of the A-frame linkage 26. Thus when the plane of the circle frame and consequently of the A-frame linkage 26 is inclined from the horizontal, the cross member 41 and mounting bracket 42 are also inclined from the horizontal.

The sensing units 40 also includes a pendulum case or horizon sensing case 43 having an integral case pivot pin 44 extending outwardly therefrom.

The main mounting bracket 42 is generally U-shaped in configuration and includes a generally fiat bracket plate 47, an arm portion 48 integral with and extending at right angles from the bracket plate 47, and an arm extension 49 integral with said arm portion at an end thereof opposite said plate and extending outwardly from said arm in generally parallel spaced relationship to the bracket plate 47. The bracket plate 47 is pivotally connected to the cross beam 41 by means of a bracket plate mounting pin integral with said plate.

The arm extension 49 is in two parts and includes matching

face plates

151 and 152 which are fastened to each other through the instrumentality of bolts 153. The face plate 152 is provided with elongated arcuate slots 154 to provide for limited rotatable adjustment of the face plates with respect to each other. The outer end of the extension arm 49 of the main mounting bracket 42 includes an integral reference collar or bearing 155 having an axis lying in a generally vertical direction.

As perhaps best seen in FIG. 6, the circle frame 23 is provided with a pair of reference

rod support brackets

156 and 157 which are welded to the circle frame and extend downwardly in clearing relationship to the bull gear flange portion of that frame to terminate in upwardly extending rod supporting end portions 158. These reference

rod support brackets

156 and 157 are mounted on diametrically opposite sides of the circle frame 23 along a diameter of that frame which has been designated by the broken line 159. The plane of the circle frame is defined by including this diameter line 159 and a second diameter line 170 which also lies in a vertical plane parallel with the longitudinal axis of the main frame of the grader. These diameter lines intersect at the center 160 of the circle frame, and a line perpendicular to the plane of the circle frame and forming the axis of the frame has been previously designated 25. A circle frame axis reference rod 161 is fixedly mounted in each of the rod supporting end portions 158. This rod 161 has an upwardly extending circle frame axis locating stud 162 integrally extending in upward direction, and the reference rod 161 is carefully adjusted and fastened as at 163 to the support bracket end portions 158 to position this axis locating stud to be exactly concentric with the circle frame axis line 25.

With the stud 162 rotatably mounted inside of the reference collar 155 of the main mounting bracket 42, and with the bracket plate mounting pin pivotally mounted in the cross beam 41 to lie on the longitudinally extending diameter line 170, any change in the angle of the circle frame plane, and consequently in the circle frame axis 25, will be reflected exactly by a change in the position of the bracket plate 47.

A pair of main bracket mounting ears 166 and 167 are integral with the bracket plate 47 and have cylindrical openings therethrough having a common upright support axis parallel with circle frame axis line 25 and passing through longitudinally extending diameter line 170. A generally upright support plate 172 has upright

support plate ears

173 and 174 integral therewith and extending outwardly therefrom. The support plate 72 and the bracket plate 47 are mounted in pivotal relationship to each other by a pintle pin 175 extending through bracket mounting ears 166 and 167 and

support plate ears

173 and 174 on the upright support axis. The previously mentioned case pivot pin 44 is pivotally mounted to the support late 172 on an axis lying in the vertical plane defined by the cross beam axis line 25 and the diameter line 170.

The circle frame 23 includes an'outer slider 179 which is slidably supported in tracks or slides 178 extending outwardly from and forming part of the A-frame bracket 32 in any conventional or desired manner. The earth working grader blade mounting brackets 22 are attached to this slider 179, and as it rotates with respect to the A-frame and the slides 178, the blade 21 will also rotate about the axis 25 of the circle frame 23. As seen in FIGS. 2, 3 and 6, the inner peripheral edges of the slider 179 have gear teeth and form what is commonly called a bull gear. These gear teeth are used to rotate the circle frame slider about its tracks or slides 178 through the use of a suitable gear driven from a gear housing 181. This gear housing is power driven through conventional mechanism (not shown). Thus the earth working blade 21 can be moved to any desired transverse angle with respect to the longitudinal axis of the grader. A lower working edge 100 of the earth working grader blade 21 will define the work plane of the earth being graded as the grader moves in the direction of the longitudinal axis of the main frame 16 and in the direction of a vertical plane passing through the circle frame diameter line 170. This work plane will be precisely parallel with the plane of the circle frame as defined by the

diameter lines

170 and 159. By accurately controlling this circle frame plane, the work plane is controlled.

As the gear teeth of the circle frame and the gear in the gear housing 181 are utilized to rotate the circle frame thus changing the' angular relationship of the diameter line 159 to the diameter line 170; in every case except where the working edge 16!) is horizontal, the plane of the circle frame will change. Unless the linkages 30 and the associated .power mechanism are used to correct this change to restore the same plane, the work plane will deviate from that desired. The parallel relationship of the axis of the reference collar to the upright support axis of the main bracket mounting ears 166 and 167 automatically accomplishes this correction.

As perhaps best seen in FIGS. 4 and 6, inside of the pendulum case or horizon sensing case 43, a pendulum 50 is mounted on a pendulum shaft 51 which in turn is rotatably mounted on suitable bearings 52, 52 in the case 43. The bearings 52, 52 are anti-friction bearings and permit the shaft 51 to rotate very easily. The pendulum 50 is mounted for movement about the longitudinal axis of the shaft 51 but is restrained from movement longitudinally along the shaft. The pendulum has a pair of

integral vanes

53, 53 positioned on opposite sides thereof. These vanes are spaced very slightly inwardly from the corresponding side edges of the case 43. Two other side surfaces 54, 54 of the pendulum are spaced inwardly a relatively greater distance from their corresponding side edges of the case 43. This is to allow the pendulum to move from side to side within the pendulum case as it pivots about the axis of the shaft 51. A pair of

stop bolts

55, 55 are threadably mounted as at 56 with respect to the side edges of the pendulum case 43. The bolts are aligned with

side surfaces

54, 54 of the pendulum and are adapted to engage these side surfaces to prevent the pendulum from swinging farther than necessary to operate the control system. The pendulum case 43 is filled with a highly refined oil, indicated at 57, which dampens the movement of the pendulum as it swings about the axis of shaft 51. The small clearance between vanes 53 and the corresponding sides of the pendulum case is to constrict the flow of oil as the pendulum swings.

The tilting of the case 43 about its pivot pin 44 is controlled through the linkage 60 which is pivoted to the case 43 as at 135. The operation of this linkage and the manner in which it fixes the angular relationship of the horizon sensing pendulum case 43 with respect to the upright support plate 172 will be explained more fully later.

Pendulum shaft 51 has an end portion 61 which extends outwardly from the case 43 into a housing 59 which is integral with the case. An actuating lug or ear 62 is fixedly attached to the shaft end portion 61. As best seen in FIG. 5, a first switch 63 is mounted on housing 59 on one side of the lug 62 and a second switch 64 is mounted on the housing on the opposite side of the lug 62. Actuating buttons65, 65 of the switches are positioned adjacent the lug.

As seen in FIG. 7, a flasher 102 is connected from a source of electromotive force 73 through each of the

switches

63 and 64 to a reversing switch 103. This reversing switch can be a three-position switch in which the center or disconnect position can serve as the off switch for the control apparatus. A separate power off and on switch 104 can be also utilized if desired.

When reversing switch 103 is thrown to the upward position as seen in FIG. 7, the power will flow through the flasher and switch 63 (when closed) to a relay 105 which will cause a first solenoid 106 to he energized. Power will flow through the flasher and switch 64 (when closed) to a relay 107 which will power a second solenoid 108. With the reversing switch in this upward position, tilting of the pendulum case to cause the lug 62 to close switch 64 will cause the second solenoid 108 to be energized intermittently every time the flasher permits the flow of power therethrough, and solenoid armature 109 will be moved to the left as seen in FIG. 7. Solenoid operating arm 110, integral with the armature 109, will also move to the left. When the flasher is not passing current, the springs 111 and 112 will center the armature to the position as seen in FIG. 7.

When the case moves so that the lug 62, under the urging of the pendulum 50, closes switch 63, current through the flasher 102 will cause current to flow through the first solenoid 106, and the solenoid arm 110 and armature 109 will move to the right as seen in FIG. 7. When current stops flowing through the flasher, the springs will again center the armature.

The action described above results in a series of intermittent incremental movements of the armature arm 110 in direction determined by the positioning of the reversing switch 103 and by the relationship of the pendulum 50 and lug 62 with respect to the horizon sensing case 43 and the switches mounted with respect thereto.

The solenoid mechanism may be enclosed in a solenoid box 113 as seen in FIG. 2, and the controls for utilizing the intermittent forward or reverse thrusts of the solenoid arm 110 include a control shaft 115 fixedly mounted in the cab 19 on upstanding bearing lates 116. First and second rock

shaft control arms

123 and 124, respectively, are freely pivotally mounted on a control shaft and a pair of rock shaft control linkages 125 and 126 pivotally connect these arms and their respective first and second rock shaft control levers 33 and 34. A control tube 117 is freely rotatably mounted on the control shaft and is slidable longitudinally along it. A solenoid contlrlolled arm 118 is pivotally mounted to the solenoid operating arm 110 and is keyed to the control tube 117 to be able to cause it to rotate, but to be freely slidable longitudinally with respect to it. Clutch dogs 119 and 120 are fixedly positioned on opposite ends of the control tube 117, and apertures are provided in each of the first and second rocker

shaft control arms

123 and 124 for receiving their respective clutch dogs when the control tube is slid -by a shifting mechanism '131 toward that particular control arm. The shifting mechanism 131 is a manually operable lever attached to the control tube with a suitable collar.

The parts are positioned in FIG. 2 with the dogs out of engagement for purposes of clarity; 'but it will be understood that with the clutch dog 119 in locked relationship with respect to the first rock shaft control arm 123, movement of the solenoid operating arm 110 away from the solenoid box 113 will cause the first rock shaft control lever or handle 33 to be moved back toward the machine operator to the end that rock shaft control rod 36 activates its rock shaft to result in a change in the horizontal positioning of its corresponding link 30 with a consequent change in the angular relationship of the circle frame plane and consequently thework plane as determined by the loci of movement of lower working edge 100 of the greater blade 21. Since the solenoid operating arm 110 is only in the activated position momentarily while the flasher is passing current, the increment of angular displacement of the operating plane will be slight. If the incremental movement is not sufficient to cause the lug 62 to move into clearing relationship with respect to the closed switch which originally triggered the movement, then when next the flasher fires, a further incremental movement in the same direction will take place. As soon as a particular small movement is sufiicient to cause the

switch

63 or 64 to move to the open condition, no such further control movements.

will be forthcoming.

Should the grader operator want the earth working grader blade 21 to make a deeper or shallower cut while the clutch dog 119 is keying the angular movement of the control tube 117 to that of the first rock shaft control arm 123, he has merely to operate the second rock shaft control handle 34 to cause the right side of the A-frame 26 and circle frame 23 to be raised or lowered as desired. As the pendulum attempts to maintain its vertical relationship, it will activate one of the

switches

63 or 64, and the automatic control mechanism just described will operate to raise or lower the left side of the A-frame and circle frame to maintain or re-establish the desired work plane.

A main object of the invention is to permit the ready establishment of any desired work plane with respect to the horizontal, and to maintain that plane while operating the grader. Since the upright support axis of the pintle 175 is always in exact perpendicular relationship to the work plane as defined by the loci of the lower working edge 100 of the earth working blade 21 as it moves in the direction of the longitudinal axis of the grader, it is necessary only to establish the angular relationship" of the horizontal sensing case with respect to the upright support plate 172 and the upright support axis which is fixed with respect to that plate. This is done by utilizing the connection at 135 between the linkage 60 and the top portion of the case 43. A reversible motor 121 operating through a suitable gearing 122 moves the link 60 longitudinally of its own axis to rotate the case 43 about its pivot pin 44.

In order to indicate the extent of the rotation of the case 43 with respect to the support plate 172, and consequently the angular relationship of the work plane of the grader to the horizontal, a generally rectangular indicia frame 74 of tubular material is fixedly mounted r 7 through the instrumentality of U-sh aped arm 75 to the top of the upright support-plate 172. An indicia plate 76 is calibrated in degree-s or in slope and is fixedly positioned at the top of the indicia frame 74. An indicator cable 77 is fixedly mounted with respect to opposite sides of the top of the case 43 by an indicator cable mounting bracket 78 and extends into the tubular material of the indicia frame 74, up through and clear around the frame. The underside of the tubular material of the indicia frame is open along the top edge thereof to allow an indicator needle 79, attached to the indicator cable 77, to extend under the indicia plate 76 and up in front of it to position where the relative angular positioning of the case 43 with respect to the support plate and consequently with respect to the work plane of the grader can be indicated.

In order to maintain the pendulum axle 51 in exact alignment with the longitudinal axis of the grader, it is necessary that the plane of the upright support plate 172 be maintained in perpendicular relationship to this longitudinal axis. This is accomplished by the use of a stiff-legged tie bar linkage 80 which is pivotally mounted through a double pivot joint 81 to a forward portion of the main frame 16 and is pivotally mounted as at 82'to U-shaped arm 75 at position offset from the center of the grader.

The circuit for operating the reversible motor 121 is seen in FIG. 7, wherein a second reversible switch 38 will be normally positioned in the neutral or off condition and can be manually manipulated to cause the motor to run frontward or backward, thus to adjust the angular relationship of the case 43 to the desired work plane. The angular relationship of the case to the circle frame plane will be indicated by the indicator needle 79, which the operator will watch as he operates motor 121. As soon as the automatic controls are activated, the device of the invention will conform to the work plane of the grader to that indicated on the indicia plate by the indicator needle.

Various flasher operation rates can be used to accomplish the purposes of the invention, but in one particular set of circumstances, a flasher firing rate of 90 times per minute has been found to be most satisfactory.

What is claimed is:

1. The combination with a motor grader having a wheel mounted main frame, said main frame having an elon gated longitudinal axis, a draw bar linkage pivotally mounted at a forward end portion thereof to a forward end portion of said main frame, said draw bar linkage defining a draw bar plane and having an elongated longitudinal axis, a circle frame defining a circle frame plane and mounted on a rear end portion of said draw bar linkage to be rotatable about its own circle frame axis and ,7

to maintain a fixed angular relationship between said draw bar plane and said circle frame plane, a generally transversely positioned earth working blade fixedly mounted with respect to said circle frame, and power means to selectively raise and lower one end portion of said blade with respect to the other as the angle of the'circle frame plane is changed with respect toa horizontal plane, of: an automatic control device including a main mounting bracket pivotally mounted on the longitudinal axis of said draw bar linkage, an upright support plate pivotally mounted to said main mounting bracket on an upright support axis, means for maintaining said support axis in parallel relationship to said circle frame axis, a horizon sensing case mounted on said upright support plate and having a gravity responsive element pivotally mounted in said case on a generally horizontal pivot axis, switch means in said case associated with said gravity responsive element to be deactivated when said case and said element are in a normal vertically aligned relationship to each other and to be activated when said case and said element are in unaligned relationshipwith each other, and control means operative upon activation of said switch means power means to cause said power means to change the height of one end of said blade in a series of incremental steps.

3. The combination as specified in claim 1 wherein said means for maintaining said support axis in parallel relationship to said circle frame axis includes a circle frame axis locating stud, a circle frame axis reference rod integral with said locating stud and fixedly positioned with respect to said circle frame to locate said stud on said circle frame axis, a locating stud reference collar in concentric bearing relationship to said stud, and an extension arm integral with said main mounting bracket and said collar.

4. The combination as specified incl-aim 3 wherein said arm extension is in two parts, each part including a face plate in facing relationship to the other part, and means for fastening said plates to each other through out a limited range of angular displacements one from the other.

5. Thecombination as specified in claim 1, and meansfor varying the angular relationship of the horizon sensing case to the upright'support axis of the upright support plate.

6. The combination with a motor grader having a wheel mounted main frame, said main frame having an elongated longitudinal axis, a draw bar linkage pivotally mounted at a forward end portion thereof to a forward end portion of said main frame, said draw bar linkage defining a draw bar plane and having an elongated longitudinal axis, a circle frame defining a circle frame plane and mountedon a rear end portion of said draw bar link age to be rotatable about its own circlefr-ame axis and. to maintain a fixed angular relationship between said draw bar plane and said circle frame plane, a generally transversely positioned earth working blade fixedly mounted with respect to said circle frame to have a lower working edge thereof lying at all times in a plane parallel to said circle frame plane, and power means to selectively raise and lower one end portion of said blade with respect to the other as the angle of the circle frame plane is changed with respect to a horizontal plane, of: an automatic control. device including a main mounting bracket pivotally mountedon the longitudinal axis of said draw bar linkage which axis intersects said circle frame axis, an upright sup port plate pivotally mounted to said mounting bracket on an upright support axis which intersects said longitudinal draw bar axis, means for maintaining said support axis in parallel relationship to said circle frame axis, a horizon sensing case pivotally mounted on said upright support plate and having a gravity responsive element pivotally mounted in said case on a generally horizontal pivot axis, means for maintaining said pivot axis in parallel relationship to the longitudinal axis of said main frame, switch means in said case associated with said gravity responsive element to be deactivated when said case and said element are in a normal vertically aligned relationship to each other and to be activated when said case and said element are in unaligned relationship with each other, and control means operative upon activation of said switch means to cause said power means to change the height of at least one end portion of said blade to tend to bring said case and said element into normal vertical alignment.

7. The combination as specified in claim 6 and means to adjust the angular relationship of said horizon sensing case with respect to the upright axis of the uprightsupport plate.

8. The combination as Specified in claim 7 wherein said means for adjusting said case include a link extending from said case to said draw bar frame and power means for selectively manipulating said link in either lateral direction with respect to the longitudinal axis of the draw bar linkage to cause said case to pivot with respect to said upright support plate.

9. The combination as specified in claim 8, and means for visually indicating the angular relationship of said case to said upright plate axis.

10. The combination as specified in claim 9 wherein said means for visually indicating includes an indicia frame unit and an indicator cable unit, one of said units being fixedly mounted with respect to a portion of said case spaced from its pivotal mounting point and the other of said units being fixedly mounted with respect to a portion of said upright support plate spaced from said case pivotal mounting point, said indicator cable unit extending around a track provided by said indicia frame, an indicia plate being mounted on said indicia frame, an indicator needle being fixedly attached to said indicator cable to extend to position in visual alignment with said indicator plate, and visible indicia on said plate positioned contiguous to the various possible locations of said indicator needle.

11. The combination as specified in claim 10 wherein said means for maintaining said pivot axis in parallel relationship to the longitudinal axis of said main frame includes a stiff tie bar linkage pivotally mounted to said main frame at a forward portion thereof and pivotally mounted with respect to said upright support plate at a point on said plate spaced from the longitudinal axis of said main frame.

12. The combination as specified in claim 11 wherein said control means includes an electrical circuit means feeding intermittent electrical impulses through said switch means when activated to electromagnetic-mechanical transducers which are intermittently operative on said power means to cause said power means to change the height of one end of said blade in a series of incremental steps.

13. The combination as specified in claim 11 wherein said means for maintaining said support axis in parallel relationship to said circle frame axis includes a circle frame axis locating stud, a circle frame axis reference rod integral with said locating stud and fixedly positioned with respect to said circle frame to locate said stud on said circle frame axis, a locating stud reference collar in concentric bearing relationship to said stud, and an extension arm integral with said tmain mounting bracket and said collar.

14. The combination as specified in claim 13, and means for varying the angular relationship of the horizon sensing case to the upright support axis of the upright support plate.

15. In a road grader or the like having an earth working blade, power means operable to control the angular position of said blade with respect to a horizontal plane, and an element for sensing the relationship of the cutting edge of the earth working blade with respect to a reference plane, the improvement comprising a control circuit operable in response to said element and controlling said power means, and interrupter means in said control circuit to alternately disable said power means and permit said power means to operate when the control circuit is energized thereby giving a pulsating action to said power means.

16. The combination as specified in claim 15 wherein said control circuit is comprised as an electrical circuit, and said interrupter means comprises a device which alternately makes and breaks said electrical circuit.

17. The combination with a motor grader having a wheel mounted main frame, said main frame having an elongated longitudinal axis, a draw bar linkage pivotally mounted at a forward end portion thereof to the forward end portion of said main frame, a generally transversely positioned earth working blade, means to mount the blade to said draw bar, and power means to selectively raise and lower one end portion of said blade with respect to the other, of: an automatic control device including sensing means to sense a deviation of said blade from a preselected angle with respect to a horizontal plane, and control means activated by said sensing means to operate said power means in response to deviation of said blade from the preselected angle, said control means including an impulse producing unit which intermittently interrupts operation of said power means to change the height of one end of said blade in a series of incremental steps, wherenever the sensing means indicates the blade has deviated from its preselected angle.

18. The combination as specified in claim 17 wherein said control means includes a solenoid means to operate said power means, an electrical circuit to control said solenoid, said electrical circuit including a first switch operated by said sensing means, and an interrupter switch in series with said first switch, said inter-nt-pter switch open ing and closing at a preselected frequency.

References Cited by the Examiner UNITED STATES PATENTS 2,029,455 2/1936 Wilson 37-156 2,636,290 4/1953 Bell 37156 2,904,911 9/1959 Colee 37-156 2,941,319 6/1960 Beemer et a1 37156 2,961,783 11/1960 Bowen et a1 37156 3,094,796 6/1963 Atchley 37-156 ABRAHAM G. STONE, Primary Examiner.

R. L. HOLLISTER, Assistant Examiner.

Claims

15. IN A ROAD GRADE OR THE LIKE HAVING AN EARTH WORKING BLADE, POWER MEANS OPERABLE TO CONTROL THE ANGULAR POSITION OF SAID BLADE WITH RESPECT TO A HORIZONTAL PLANE, AND AN ELEMENT FOR SENSING THE RELATIONSHIP OF THE CUTTING EDGE OF THE EARTH WORKING BLADE WITH RESPECT TO A REFERENCE PLANE, THE IMPROVEMENT COMPRISING A CONTROL CIRCUIT OPERABLE IN RESPONSE TO SAID ELEMENT AND CONTROLLING SAID POWER MEANS, AND INTERRUPTER MEANS IN SAID CONTROL CIRCUIT TO ALTERNATELY DISABLE SAID POWER MEANS AND PERMIT SAID POWER MEANS TO OPERATE WHEN THE CONTROL CIRCUIT IS ENERGIZED THEREBY GIVING A PULSATING ACTION TO SAID POWER MEANS.