US2340169A - Road grader - Google Patents

Description

F. E. RNDT Jan. 25, 1944.

RQAD @BADER Filed July s1, 1940 6 .Sheets--SheeifI 1 /NVE/YTOE FRANKLIN EARNDT,

Jan. 25, 1944. F. E. ARNDT ROAD` GRADER Filed July 31. 1940 6 Sheets-Sheet 2 /NVEN TOR m A., E NW. L. mw @d FY. B

F` E. ARNDT Jan. 25, 19.

ROAD GRADER 6 Sheets-Sheetl 4 Filed July 3l, 1940 /NVENTQR FRANKLIN E. ARNm;

HTT'Y Jan. 25, 1944.

F. E. ARNDT 2,340,169

ROAD GRADER `Filed July s1, 1940 e sheets-sheet s 5G Elly. .9

/NVENTO/e I FRANKLIN E. ARN D1 BYZM- l ATTY.

F. E. ARNDT Jan. 25, 1944.

ROAD GRADER Filed July :51. 1940 6 Sheets-Sheet 6 /NVENTORI FRANKLIN EARND-l;

HTTX

Patented Jan. 25, 1944 ROAD GRADER Franklin E. Arndt, Galion, Ohio, assignor to The Galion Iron Works & Manufacturing Company, a corporation of hio Application July 31, 1940, Serial N0. 348,981

2 Claims.

My invention relates to road graders, and one of its objects is the provision of improved, very flexible and eiiicient means for angularly adjusting a road working implement relative to the road surface.

Another object of the invention is the provision of improved and efficient means for laterally shifting a road working implement in a road grader.

Another object of the invention is the provision of` a rotary huid-pressure motor connected through self-locking worm gearing to laterally shifting mechanism for a grader blade in a road grading machine, with the self-locking worm gearing effective to hold the grader blade in adjusted lateral position.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

' In the accompanying drawings,

Figs. 1 and 2 placed end to end, show a. power road grader embodying my improvements;

Fig. 3 is a plan view taken on the line 3-3 of Fig. 2;

Fig. 4 is a-plan view of a. portion of Fig. 3 but with the low pitch worm gearing shown more in detail;

Fig. 5 illustrates the connections for the laterallyshiting mechanism shown at the upper lefthand portion of Fig. 2;

Fig. 6 is an enlarged right-hand end eleva,

tion of the left-hand portion of Fig. 5, to illustrate the worm gearing connections to the laterally shifting arm;

Fig. 7 is an enlarged sectional elevation of the gearing for operating the circle;

Fig. 8 is a piping diagram for the rotary hydraulic motors shown in Figs. 4 and 5;

Fig. 9 is a sectional elevation of the rotary hydraulic motor for operating either the circle or the laterally shifting mechanism;

Fig. 10 is a sectional plan view of the left-hand portion of Fig. 9 taken on the center line of the motor;

11 is a sectional elevation taken on the line Y Il-ll of Fig. 9 looking in the direction of the arrows;

Fig. 12 is a sectional elevation taken on the line l2-l2 of Fig. 9 looking in the direction of the arrows Fig.13 is a sectional elevation similar to Fig. 9

but illustrating a modified motor which may be used for rotating the circle or for operating the laterally shifting mechanism;

Fig. 14 is a plan view of the left-hand portion of Fig. 13;

Fig. 15 is a sectional elevation taken on the line l5-l5 of Fig. 13, looking in the direction of the arrows; and

Fig. 16 is a sectional elevation taken on the line I6-I6 of Fig. 13, looking in the direction of the arrows.

Referring to Figs. 1 and 2 placed end to end it vwill be seen that the grader frame l1 is mounted `'at its rear end on an axle Aframe I8 carrying the internal combustion engine I9 which is connected through dual driving mechanism to the ground engaging traction wheels 20, 20, said axle frame I8, engine I9 and wheels 20 being connected together and forming a tractor or power traction unit to propel the grader. The front end of the grader frame or vehicle frame Il is mounted on a steering wheel unit 2| connected through steering mechanism 22 to a reciprocating steering hydraulic motor 23. The latter is connected between the frame I1 and the steering mechanism 22 and is controlled by a valve having an operating lever at the operators station 24. That is to say, lthe operator while on his seat 24 may turn the steering wheel 25 to actuate valve mechanism which is connected to the hydraulic motor 23 to etl'ect steering of the machine. The operator at his station as shown in Fig. l has before him all of the various levers for not only steering the machine but alsocontrolling the operation of the engine and the various adjustments in the road grader.

The drawbar frame 26 as shown in Fig. 2 is iiexibly connected at 2.1 to the front end of the grader frame Il. The rear end of the drawbar 26 has a crosspiece 28 to the ends of which are connected by means of ball and socket joints 29,' 29, the lower ends of the extensible hangers 3u, 3u, the upper ends of which are connected by ball and socket joints 3|, 3| to the laterally extending arms 32, 32 which are connected to the longitudinally extending rock shaits 33, 33 journaled in the bearings 34, 34 shown iti-Fig. 3 one on each side of said frame Il. The rear ends of the rock shafts 33 are mounted in similar bearings and are connected to laterally extending arms flexibly connected to the upper ends of piston rods 35 of a pair of double acting hydraulic motors 36, 36. From the operators station 24 either or both of the piston reciprocating hydraulic motors 36 may be operated to lift or lower the hangers 30, 30 individually and thus adjust the elevation of the drawbar 26 and its inclination transversely oi the road surface.

Carried by the drawbar frame 26 for rotation relatively thereto is a circle 31 carrying the moldboard 36 and the latters cutting blade 69. 'Ihe circle 31 carries an annular gear 4|| which meshes with the pinion 4| secured to the lower end of the shaft 42, the upper end of which is keyed at 43 to the worm gear 44, the latter being enclosed in a'casing 4I. as shown in Fig. '1.

'I'he casing 45 is provided with alower cylindrical extension 46 resting on the top of the pinion 4I as shown in Fig. '1. A bearing bushing by means of the V-belt gearing 64 shown in dotted 41 lines the cylindrical extension .46. 'I'he latter v has secured thereto brackets' 46 which are provided with upper and lower anges both at the front and-at the rear for bolting by means of the bolts 49, 49 to the upright supporting plates 56, 56 which are secured rigidly as cross-pieces to the drawbar frame 26, as shown in Fig. 3.

Also mounted within the casing 45 is a worm 5| in position to mesh with the worm gear 44. While the pinion 4| may be welded to the shaft 42 as indicated at 52 in Fig. 7, the upper end of the shaft 42 is screw-threaded to receive the nut sive, -or as shown in Figs. 13 to 16, inclusive. The

shaft 51' of the motor 56 extends rearwardly longitudinally of the center line of the drawbar frame 26 and is connected by means of the universal joint 51' to the shaft 56, the rear end of which in turnis connected by means of the universal joint 59 to the shaft 66 of the worm 5|.

An important feature of my invention is the provision of relatively low pitch worm gearing 44, 5 |-so as to be operable with considerable power in rotating the circle against such resistances as may be encountered by the grader blade 69 in contact with the road surface. 'I'he worm gearing being of low pitch is self-locking and therefore eliminates the use of the usual pin and hole locking mechanism to hold the circle in adjusted position relative to the drawbar. For example, I have in commercial machines used worms 5| each having a pitch of .75". That is t0 say. the worms have been single cut with the leads of .75". The worm gears 44 meshing with such worms in such commercial structures, have each been single cut circular pitch .75" with forty-two teeth. 'Further, in such commercial structures the Spur pinions 4| each has six teeth of the circular pitch of 2.618" and this arrangement rotates the circle which has a pitch diameter of 52" and sixty-live teeth; that is to say, 1.25 diametral pitch or 2.5138 circular pitch. The ratio of the gearing between the motor shaft 51 and the circle 91 in such commercial structures is approximately 455 'I'hese dimensions and the ratio may of course be varied as desired, but the figures are set forth merely by way of example to show that the hydraulic motor 56 must rotate its shaft 51 a great many times to rotate the circle once. In the illustration given, the shaft 51 rotates 455 times to secure one rotation of the circle. A complete rotation of the circle, however, is seldom necessary and is desired only when the grader blade 39 is to be reversed from the position shown in Fig. 2 and the grader operated by backing the same or traveling rearwardly. During ordinary operations in practice the circle may be shifted about 90 to `adjust the machine from a righthanded working machine to a left-handed working machine and vice versa. But even a quarter lines in Fig. 1, which gearing is connected to the internal combustion engine I9 by means of a take-oi! therefrom. As shown in Fig. 6, a suction pipe 65 extends into the supply tank 66. A supply pipe 61 is connected through a high pressure relief valve 66 to the return line 69. The high pressure relief valve 66 opens in the direction of the arrow 16. By operation of the .valve lever 6| supply pressure may be directed into either pipe 1| or 12 andthe other pipe then acts as the return pipe. In this manner, the direction of flow through the motor 56 will determine the direction of rotation of the latter, and the rotation of the motor shaft 51 determines the direction of rotation of the circle which carries the moldboard. It will thus be seen that the speed of the hydraulic motor 56 is controlled by the amount of oil which the pump is permitted to deliver to the motor 56. The speed of the motor 56 can be slowed down by throttling action of the valve in the manifold 62. The hydraulic motor 56 used in the commercial structures rel ferred to, can rotate at approximately 145 revolutions per minute and it will thus be seen that the circle can be rotated through approximately 90 in less than a minute. However, I wish to repeat that this reference is made merely by way oi' example to show the relatively high speed of rotation of the motor 56 and not the exact speed tnereoi: as in any event the operator at his station may so operate the valve lever 6| as to secure a slower rotation of'the motor so as to adjust the moldboard to certain definite angles relative to the line of draft of the road grading machine.

'i'he mechanism for laterally snntmg the moldboard and laterally shifting the rear end of the drawbar frame Z6 is shown in Figs. 2, 3, 5 and 6. An extensible link I3 is connected to a universal Joint 13' near one end of the cross-piece 26, as shown in Fig. 3. The other end of the extensible link 13 is -connected by means of the universal joint to the lower end of the laterally swinging arm 15. The ball 14 of the universal joint 14 is shown in Fiss'. 2. 5 and 6.

'lhe upper end of the arm 15 is keyed to the rock shaft 16 the axis of which extends longitudinally of the grader and between and below the axes of rock shafts 33, 33 and which is journaled in the bearing 11 mounted on the bracket I6 secured to the cross-plate 19 between the forwardly converging members 6u, 66 of the supporting frame 6|.

The rock shaft 16 may also be journaled in the bearing 62 secured to the plate 19. The rear end of the rock shaft 16 is keyed to a worm gear 63 which meshes with the worm 64. 'I'he -worm 64 and worm gear 63 may be mounted in the casing 65 which is secured to the vertical -plate 66, the ends of which are welded to the converging members 66, 66 of the frame 6|.

The shaft 61 of the worm 64 is connected to many rotations of the motor shaft 96 will be nec essary to move the arm 15 throughl a small angle. Such low pitch gearing enables the laterally shifting mechanism to be operated withconsiderable power so that the moldboard may be shifted laterally of the road surface even though the scraping blade may be in contact therewith. Inasmuch as the motor 91 is of relatively high speed under the control of the operator at his station 24, thelateral shifting of the moldboard may be eifected in a short space of time. By means of the valve handle 98 shown in Fig. 8, the motor 91 may have directed to it through the pipes 99 and the supply and return ow of the oil or other fluid-pressure medium. The motor 91 may be reversed or controlled to operate in either direction, and therefore the arm may be swung laterally of the vehicle frame either toward one side or toward the other side and consequently the grader blade with the assistance or adjustment of the extensible links or hangers 30, 30, may be adjusted to bank-sloping position at either side of the machine.

While the frame 8| may be connected to and i extend forwardly from the dashboard |0| of the power traction unit I9, it should be understood that the forward end of the frame 8| is rigidly connected to the spaced-apart side members of the vehicle frame I1. The motor 91 may be mounted on the cross-plate |02 between extensions |03, |03 from the converging members 80, 80. I prefer, however, to mount the motor rigidly on a cross-piece |04 rigidly attached to the tops of the spaced-apart channels of the main frame |1, as shown in Fig. 2.

In advance of the moldboard a scarier |05 mounted on a frame |06 pivoted at |01, may be adjusted by means of the hangers |08 on opposite sides of the machine. Such hangers |08 are similar to the hangers 30, 30 as to including a rod |09 telescoping into a tube ||0 and held in position by pin tting in registering holes.

The upper ends of the hangers |08 are connected to bell cranks |I2 pivoted at ||3 to the vehicle frame I1. A reciprocating hydraulic motor I|4 is pivoted at its rear end to the bracket ||5, and its piston plunger ||6 is pivoted at II'| to the bell cranks I |2. The pair of motors 36, the steering motor 23 and the scarier motor I4 may be controlled by the operator at his station at the manifold similar to that designated at 62 in Fig. 8 by adding valves for the control of the piston motors as well as the rotary motors.

The rotary motor 56 shown in Fig. 9 comprises a cylinder ||8 to the ends of which are secured the end plates ||9 and |20. The plate ||9 is secured to the cylinder I|8 by means of the circumferentially spaced cap screws |2|, |2|. The plate is secured to the other end of the cylinder ||8 by means of the circumferentially spaced cap screws |22, |22.

Within the casing ||8 is a bearing block |23 which is provided with an annular shoulder |24 which ts against the inner face of a circular opening in the end plate ||9. The left-hand end of the bearing block |23 is screw-threaded to receive the nut |25 which when tightened in place against the end plate I9, holds the bearing block |23 rigidly connected in adjusted position to the end plate ||9. The bearing block |23 is preferably keyed at |23' to the end plate I9.

J ournaled on the bearing block |23 is a cylinder block |26 which is .provided with a plurality of circumferentially spaced cylinders, in this instance ve in number. These cylinders may be formed by boring entirely through the block from end to end and axially thereof and then providing the left-hand ends of each of the bores with screw threads to receive the screw-threaded plugs |21, |21, as shown in Fig. 9.

Radial drain openings may also be bored and closed by screw-threaded Plugs |28, |28. Solid pistons |29, |29 fit into the cylinders for reciprocation relatively to the cylinder block |26 along linesvparallel to the axis thereof.

The outer ends |30, |30 of the pistons |29 have the shape of a frustum of a cone and are adapted to bear against the thrust plate or swash plate |3|, the center of which is provided with a large opening |32 throughV the cylindrical extension |33. Surrounding the cylindrical extension is a ball bearing race |34.

Connected to the inner side of the end plate |20 preferably by being made integral therewith, is a swash plate box or thrust block |35 having an annular seat |36 for receiving the bottom of the outer ball bearing race |31. The outer cylindrical surface of the outer ball bearing race |31 ts a corresponding cylindrical seat |38 in the swash plate box |35. A plurality of circumferentially arranged balls |39, |39 completes the ball bearing between the swash plate or thrust plate |3| and the thrust block or swash plate box |35.

The left-hand end of the cylinder block |26 iits against a thrust ball bearing |40 which in turn is seated against the annular shoulder |4| on the stationary bearing block |23.

The pipes 1| and `12 vshown in Fig. 8 are screwthreaded into the left-hand end of the bearing block |23 for communication to the passageways |42, |43 which lead inwardly to the ports |44 and |45 for registry one after another with the ports |46, |46 which lead to the cylinders |29, |29', as shown in Fig. ll. The ports |46 may be bored radially and then closed by means of the screw plugs |28, |28, as shown in Fig. ll. As shown in Fig. ll which is a sectional view taken on the line |-II of Fig. 9 looking in the direction of the arrows, two of the cylinders |29' are in communication with the pipe 12 and two other cylinders |29 are in communication with the other piper 1|, while the lowermost cylinder is not in communication with either pipe 1| or 12, The right-hand end of the cylinder block `|26 is splined at |41 to the shaft 51, the outer end of which is adapted to be pinned at |48 to the universal joint 51 shown in Fig. 2.

An annular shoulder |49 on the shaft 51 fits against the inner race of a ball bearing |50, the outer race of which fits into an annular recess on the inside of the end plate |20. Inasmuch as the chamber |5| inthe casing of the hydraulic motor may be filled with oil, it is desirable to provide an oil seal at |52 in the form of a stuiling box having members spring-pressed between the inner race of the ballbearing |50 and the cap plate |53 in which the shaft 51 is journaled. The cap plate |53 may be secured by means of the-machine screws |54, |54 to the cylindrical extension |55 from the outer side ofthe plate |20. Within the cylinder block |26 is a chamber |56 which communicates with the chamber I5| through the openings |51, |51.

It should be understood that either of the ports |44 or |45 may be the supply port and the other the einem' port. In other werde, either the pipe 1| or the pipe 12 may be the supply line and the other pipe the return line. Due to leakage along the pistons |29 on the supply pressure side of the motor, an undesirable pressure may, be built up in the chamber |5| and'it is highly desirable that such built-up pressure is provided with relief. For this purpose the passageways |42 and |49 are extended -as shown at |58 and |59 in Fig. 10 for connecting the passageways |42 and |43 to the chamber |56. At the right-hand end of the passageways |58 and |59 are mounted ball check valves |60, |6| which lopen from the chamber |56 but close automatically when pressure is exerted in tending to cause a flow from the passageway |56 into the chamber |56. However, `one of the passageways |58 or I 59 is always an exhaust passageway and therefore built-up pressure in the chamber |5| may easily be relieved by the check valve opening from the chamber |56 into the exhaust passageway. For instance, if the passageway |56 is connected to the supply pipe 1|, the check valve |60 will be held closed by the supply pressure. -The built-up pressure in the chamber |5| will open the check valve |6| for flow of oil from the chamber |56 into the exhaust passageway |59 tothe return pipe 12.

The hydraulic motor 56 may be detachably mounted on the plate 55 (Figs. 2 and 4) by means of screws inserted through the plate 55 into screw-threaded openings in the feet |62, |62 shown in Figs. 9 and l2. In a similar manner, the motor 91 may be detachably mounted on its supporting plate |04 by means of screws inserted through openings therein into the screw-threaded openings |63, |63 in the feet |64, |65 shown at the bottom of the casing l66 in Figs. 13, 15 and 16.

'I'he modied motor shown in Figs. 13 to 16, inclusive, is composed of a cylinder block |91 which remains in stationary position during operation of the motor. As shown in Fig. 15, which is a sectional elevation taken on the line |5|5 of Fig. 13 looking in the direction of the arrows, the pistons |68 t in cylinders |69 each of which may be formed by boring and counter-boring and then closing the left-hand ends as viewed in Fig. 13 with screw plugs |10, |10. The radial ports |1|, |1| may be formed by radial boring, with the outer ends closed by the screw plugs |12, |12. The right-hand ends |13 of the pistons |66 each has the shape of a frustum of-a cone in position to engage the thrust plate |14 mounted by means of the thrust ring roller bearing |15 on the tilted thrust block |16 which is keyed at |11 to the shaft |181. The thrust plate |14 is held to an annular seat |19 on the thrust block |16 by means of the ring plate |80 held in place by the cap screw |8| extending through the plate |66 into the screw-threaded opening in the block |16, as shown .in Fig'. 13.

The left-hand end of the block |16 as shown in Fig. 13, ts against an annular shoulder |62 on the shaft |18 while the right-hand end of the thrust block |16 rests against the inner race of a roller thrust bearing |83 surrounding a reduced portion |84 of the shaft |18. A-further reduced portion 96 extends through a liquid seal |85 comprising a spring-pressed stuing box held in place by the cap |86 and the 'screws |81, |81.

An enlarged portion |88 of the shaft |18 has an annular shoulder fitting against the inner race 69 of the ring thrust bearing |90, the outer race |9| of which nts against an annular shoulport block |94 rotates.

assunse inderblock. Itwillthusbeseenthatendwise movement of the shaft |16 relative to the motor frame or casing is resisted by the oppositely arranged thrust bearings |86 and |90.

The inner end of the shaft |18 is keyed at |93 to a reduced extension of the cylindrical" port block |94 which by reason of its connection l t'o the shaft |16 rotates with the latter during operation of the motor.

The pipes 99 and |00 of Fig. 8 are adapted to be connected to the screw-threaded ports 99' and |06 shown in Fig. 14. The port 99' communicates withthe cylindrical port |95 which is located in the cylinder block and completely surrounds the rotating cylindrical port block |94. In a similar manner, .the port |00 communicates with the circular port |96 which is located in tha cylinder block and completely surrounds the cylindrical port block |94.

` In the cylindrical port block are two radial openings |91 and |98 on opposite sides as shown in Fig, 13. The ports |91 and |98 communicate with separate passageways |99 and 200 in the cylindrical port block |94. 'I'he passageways |99 and 200 are parallel to each other and parallel to the axis of rotation of the shaft |18. These passageways lead toward the left as viewed in Fig. 13 and respectively communicate with the ports 20| and 202. Each of the passageways |99 and 200 may be formed by boring and their left-hand abends closed by screw plugs as illustrated at 203 f-"in Fig. 13.

134s shown in Fig. 15, the port |00' is in communication with the ports |96, |91, |99, 20|, and two oftlreylinders |69 at the lower right-hand portion of Fig. 15. The other port 99' communicates with the ports`l95, |98, 200 and 202, thereby communicating with the cylinders |69 at the lower left-hand portion of Fig. 15. The uppermost cylinder is cut oil when the port block |94 is in the position shown in Fig. 15.

As shown in Fig. 13, a cap plate 204 is secured in place by means of the screws 205, 205 to close the cylindrical opening in which the cylindrical A passageway 206 extends axially through the port block |94 so that oil\e scaping into the chamber 201 may ow into the main chamber 208 of the motor. The righthand end of the motor may be provided with an lnspectionopening normally closed by means 0f the screw plug 209.

It is important to note that two separate parallel passageways 2|0 and 2|| lead respectively from the ports 99 and |00' into the chamber 208. The passageways 2 |0 and 2|| are parallel to each other and parallel to the axis of rotation of the shaft ns. The passageway zu leads from the chamber 208 to the port |00' and is therefore seen in full lines in Fig. 16 which is a section taken on the line |6|6 of Fig. 13 looking in the direction of the arrows. The other passageway 2|0 is shorter. as may be seen in the elevational view of Fig..13.

'I'he right-hand ends of the passageways 2|0 and 2|| are each provided with a check valve 2|2, 2|2 which areso arranged as to open from the chamber 208 into the passageways 2|0 and In other words, when either port 99 or |00' is a supply port, the check valve connected thereto remains closed by supply pressure, while the other check valve connected to the exhaust automatically opens to relieve the chamber 206 of built-up pressure therein due to leakage past the pistons or otherwise.

der surrounding the chamber |92 within the cyl- 75' In both the form of` rotary motor shown in Figs. 9 to 12, inclusive, and in the form shown in Figs. 13 to 16, inclusive, the motor mechanism is entirely enclosed and no -return pipes to the supply tank are included aside from those already described in connectio with Fig. 8. The check valves in the motors]-A assure maintaining the chambers I5| and 208 filled with oil for lubricating purposes and the interior pressure is limited by the check valves. In other words, the check valves obtain these advantages which are particularly desirable in road graders because the rotary motors are widely spaced from the operators seat 24 under which the supply tank 66 is located, as shown in dotted lines in Fing. 1.

The hydraulic motor per se herein disclosed is claimed in my divisional application, Serial No. 379,971, led February 2l, 1941, for an improvement in road graders.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as dened by the claims hereto appended, and I therefore wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In a road grader, the combination with a vehicle frame, of a. drawbar flexibly connected at its forward end to the forward end of said frame, a. grader blade carried by said drawbar, means for adjusting said drawbar relative to said frame, a longitudinal shaft mounted' on said frame for rocking movement relatively thereto, and actuating arm on said shaft, a link connecting said arm to said drawbar, a rotary hydraulic motor mounted on said frame and having a rotary shaft,

driving connections between said motor and said first-named shaft comprising two sets of serially arranged worm gearing to enable the shaft of said motor to extend longitudinally of said vehicle frame, and means for controlling said rotary hydraulic motor to effect lateral swinging of said arm to laterally shift the rear end of the drawbar, the worm gearing aforesaid serving to lock the drawbar in adjusted laterally shifted position.

2. In a road grading machine, the combination with a vehicle comprising a supporting frame. of a drawbar flexibly connected at its forward end to said frame, a grader blade carried by said drawbar, spaced-apart rock shafts mounted on said frame to extend longitudinally thereof to the top side of said frame, crank arms on the ends of said rock shafts, upright reciprocating hydraulic motors connected to the rear crank arms, extensible hangers connected between the forward crank arms and the rear end of said drawbar, a third rock shaft extending longitudinally and centrally of said frame below the top thereof, a crank arm on the forward end of said third rock shaft, an extensible link connecting said lastnamed crank arm with one side of the rear end of said drawbar, a rotary hydraulic motor mounted on said supporting frame between the crank arms at the forward ends of said firstnamed rock shafts, a double set of worm gear reductions between the rear end of said rotary hydraulic motor and the rear end of said third rock shaft, and means for controlling said hydraulic motors to secure individual operation thereof to effect adjustment of said grader blade, laterally of the vehicle and in elevation and inclination.

FRANKLIN E. ARNDT.

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