Implement connecting coupler mechanism

Abstract

A coupling mechanism is provided for coupling an implement to a prime mover, such as a motor grader, with a fixed bolster plate. The coupling mechanism includes a grader assembly with a bolster plate frame adapted to be fixedly mounted to the bolster plate, a moveable grader coupling frame supported for movement on and with respect to the bolster plate frame, the coupling frame extending in a generally vertical direction and having upper grader coupling means, power means supported on the bolster plate frame and connected to the moveable grader coupling frame, guide means for guiding the upper grader coupling means in two directions, outward from and upward with respect to the bolster plate frame when the implement is being connected and downward with respect to and inward toward the bolster plate frame when the implement is being disconnected and moveable grader latching means carried by the moveable grader coupling frame. The assembly also includes an implement assembly mounted on the implement, and including an implement frame with upper implement coupling means complementary to the upper grader coupling means and implement means complementary to the grader latching means.

Description

RELATED APPLICATION

This application is directed to subject matter related to an application of applicant being filed concurrently herewith, bearing the same title.

BACKGROUND OF THE INVENTION

Implement hitches of various sorts are old and well known. Examples of the patent art include U.S. Pats. to Sorensen, No. 2,888,995, Hess, No. 2,979,137, Todd, No. 3,195,651, and Stuart, No. 3,417,886. Most of the hitches described in the prior art and practically all of the quick hitches known commercially heretofore have been designed for use with prime movers which have vertically moveable arms of some sort, such as front end loaders, or tractors with hydraulically actuated lifting arms or links to which a connecting frame can be mounted. It is believed that no commercially satisfactory quick connecting implement hitch has been offered anywhere for attachment to a prime mover such as a motor grader with a fixed attachment surface, referred to hereinafter as a bolster plate.

This invention is directed to the coupling of heavy implements such as dozer blades, snow plow attachments and heavy buckets to a bolster plate on heavy prime movers such as road graders. The invention is described as applied to motor graders, although the term is used broadly in the claim to indicate any heavy prime mover with a bolster plate.

One of the objects of this invention is to provide a coupling mechanism for motor graders which permits quick and easy connecting and disconnecting of attachments such as buckets, blades and plows, and at the same time mounts the implement firmly, securely, and without slop in the connection.

Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.

SUMMARY OF THE INVENTION

In accordance with this invention, generally stated, a coupling mechanism is provided for connecting a motor grader to and disconnecting it from an implement, comprising a grader assembly including a bolster plate frame and means for fixedly mounting the bolster plate frame on a bolster plate of the motor grader, a moveable grader coupling frame supported on the bolster plate frame, extending in a generally vertical direction and having upper grader coupling means, power means, supported on the bolster plate frame and connected to the moveable grader coupling frame, guide means for guiding the upper grader coupling means part of the coupling frame in two directions, outward from and upward with respect to the bolster plate frame when the implement is being connected and downward with respect to and inward toward the bolster plate frame when the implement is being disconnected, and moveable grader latching means carried by the coupling frame at a position spaced from the upper grader coupling means; and an implement assembly mounted on the implement, the implement assembly including an implement frame having upper implement coupling means complementary to the upper grader coupling means and implement latching means complementary to the grader latching means.

In the preferred embodiment, the bolster plate frame has a back plate, spaced, parallel side rails, and clevis ears on the lower part of the back plate positioned laterally between the side plates. The moveable grader coupling frame is generally rectangular in front elevation, with heavy top and bottom generally horizontal cross beams. The top cross beam has, on its lower side, clevis ears oppositely disposed from the bolster frame clevis ears and carries on its upper side two, spaced, cone-shaped coupling prongs mounted with their smaller ends projecting upwardly. The moveable grader coupling frame is connected to the bolster plate frame by means of upper and lower pairs of links, pivotally mounted at one end on the bolster plate frame side rails and at their other end on the grader coupling frame, the upper of the pairs of links being longer than the lower of the pairs, and the vertical spacing of the pivot points of the links on the coupling frame being greater than the vertical spacing of the pivot points of the links on the bolster plate frame. Hydraulic cylinder-piston assemblies are pivotally connected to and extend between the oppositely disposed clevis ears of the bolster frame and the top beam of the coupling frame. The latch means of the coupling frame is a single latch pin journaled for reciprocating movement. The implement frame has prong receiving sockets with open-ended seats of a diameter larger than the smaller ends of the conical prongs of the grader coupling frame but smaller than the diameter of a projecting conical portion of the prongs closer to the top beam of the grader coupling frame, so that the prongs and sockets are self-tightening. The implement latching means is a latch plate having a hole of a size and position to receive the latch pin of the grader coupling frame. A step or toe plate along a lower part of the implement frame is positioned to project beneath the bottom cross beam of the grader coupling frame when the implement frame is coupled, to cage the grader coupling frame between the toe plate and the sockets. In the preferred embodiment, the implement frame sockets, the latch plate and the toe plate are all adjustable with respect to the implement frame. Preferably, the latch plate is so made as to be capable of mounting to receive a latch pin journaled for either vertical or horizontal movement.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, FIG. 1 is a view in perspective of a grader assembly portion of one illustrative embodiment of this invention, mounted on the front end of a motor grader;

FIG. 2 is a view in perspective of an implement assembly portion of one illustrative coupling mechanism of this invention mounted on a dozer blade;

FIG. 3 is a view in side elevation of the grader assembly of FIG. 1 connected to an implement assembly substantially like the implement assembly of FIG. 2, mounted on a snow plow;

FIG. 4 is a top plan view of another embodiment of a grader coupling frame part of the grader assembly portion of the coupling mechanism of this invention;

FIG. 5 is a view in rear elevation of the grader coupling frame shown in FIG. 4;

FIG. 6 is a view in side elevation of the grader coupling frame shown in FIGS. 4 and 5;

FIG. 7 is a view in side elevation of still another embodiment of implement assembly portion, mounted on a bucket;

FIG. 8 is a view in front elevation of the grader coupling frame shown in FIGS. 1 and 3;

FIG. 9 is a view in side elevation of a bolster plate frame portion of the grader assembly shown in FIGS. 1 and 3;

FIG. 10 is a view in front elevation of the bolster plate frame shown in FIG. 9; and

FIG. 11 is a view in perspective of the front of the implement assembly shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and particularly to FIGS. 1, 2, and 8-11 for one illustrative embodiment of coupling mechanism of this invention, reference numeral 1 indicates a motor grader with a bolster plate 2 rigidly fixed to the chassis at the front end of the grader. Holes, not here shown, are provided in the bolster plate. A grader assembly 10 is rigidly mounted on the bolster plate 2, by means of heavy bolts and nuts 4. The grader assembly includes a bolster plate frame 15, having a back plate 16 with holes 6 corresponding to the bolster plate holes, through which the bolts 4 extend to mount the back plate directly to the bolster plate 2, parallel side rails 17 and 18 welded to the back plate, and clevis ears 20 (best shown in FIGS. 9 and 10) positioned symmetrically between the side rails 17 and 18. The back plate 16 is bent forward below the bolster plate, and the side rails are formed accordingly, as shown in FIGS. 1, 9 and 10. In this embodiment, the side rails 17 and 18 are made up of pairs of spaced plates 19 and 29 one pair at each side of the back plate 16. Each of the side rails 17 and 18 carries an upper bearing pin 21 and a lower bearing pin 22 extending between and journaled in openings, which may be bushed, in the plates 19 and 29 of each side rail. The upper bearing pins 21 of the two side rails are axially aligned, and their common axis is closer in a forward direction to the bolster plate 2 than is the axis of the lower bearing pins 22, which are also axially aligned.

A moveable grader coupling frame 30, includes a top beam 31, a bottom beam 32, and coupling frame side rails 33 and 34, made up of spaced side plates 35 joined by webs 36 and cross plates 37, as shown in FIG. 8. Securely mounted, as by welding, on the upper side of the top beam 31 and projecting upwardly therefrom are coupling prongs 40. In the embodiment shown, the coupling prongs 40 have a cylindrical portion 41 next to the top surface of the top beam 31, and a truncated conical portion 42 projecting upwardly therefrom. In this embodiment, the coupling prongs 40 are located on the top beam 31 by means of shanks 43 integral with the prongs 40 and extending into holes in the upper part of the top beam, as shown particularly in FIG. 5.

Secured to the underside of the top beam 31 are top beam clevis ears 45, aligned with the clevis ears 20 of the back plate 16.

The side rails 33 and 34 carry upper and lower coupling frame bearing pins 47 and 48, the upper coupling frame bearing pins 47 being axially aligned and the lower coupling frame bearing pins 48 being axially aligned and both upper and lower bearing pins being spaced laterally the same distance as the upper and lower bearing pins 21 and 22 of the bolster plate frame.

Pivotally mounted on and extending between upper bearing pins 21 and 47 are upper links 50. Pivotally mounted on and extending between lower bearing pins 22 and 48 are lower links 55. The upper links 50 are longer than the lower links 55.

The vertical spacing of the upper and lower bearing pins 21 and 22 is less than the vertical spacing of the upper and lower coupling frame bearing pins 47 and 48, so that the links 50 and 55 diverge in a direction toward the coupling frame 30. It will be observed that the links 50 and 55 are high in relation to their lateral width, making them rigid in a vertical plane and narrow at their bolster plate end, and that the links of both pairs are short relative to the vertical distance between their pivot axes, an essential feature for a practically operative device.

Hydraulic cylinder-piston assemblies 60 are connected by clevis fittings at one of their ends to a clevis pin 61 in the clevis ears 20 on the bolster frame back plate 16 and at their other end to a clevis pin 62 in the corresponding clevis ears 45 on the top beam 31 on the grader coupling frame 30.

Each of the hydraulic cylinder-piston assemblies 60 includes a cylinder 63 and a piston 64. Top and bottom supply and exhaust ports in the cylinder are conventional, as are the fittings to them and hydraulic lines connected to the fittings and to suitable controls in the cab of the grader, and are not here shown.

A latching mechanism 70, best shown in FIG. 8, is carried by the coupling frame 30 and includes a latch receiver 71 made up of two, spaced, parallel latch walls 72 with aligned latch pin receiving holes in them, and gusset plates 73, all welded to the top surface of the bottom beam 32; a latch pin bearing sleeve 74, welded to the outer side of one of the latch walls 72 concentrically with the opening in the latch wall; a latch pin 75 slidably mounted in the bearing sleeve 74; a piston rod 76 connected at one end to the latch pin 75 and at its other end to a piston in a hydraulic cylinder 77 bolted to the inside surface of a side plate 35. The latch pin 75 is of a length to clear the space between the latch walls 72 when the latch pin is retracted, and to project across the space and into the hole in the opposite latch wall, when extended.

Referring now to FIGS. 2 and 11 for one illustrative embodiment of implement assembly portion of the coupling mechanism, reference numeral 101 indicates an implement, in this illustration, a dozer blade, equipped with an implement assembly 102. In this embodiment, the assembly 102 includes an implement frame 103, having heavy side rails 104 and 105, spaced apart a distance greater than the width of the grader coupling frame 30, and connected top and bottom by an upper cross members 110 and a lower cross member 112. The upper and lower cross members 110 and 112 are also connected by truss bars 118. In the embodiment shown, the upper cross member is in the form of a heavy angle iron with an upper leg substantially horizontal. The lower cross member is in the form of a heavy channel with a center stiffener plate between the forwardly extending flanges of the channel.

Bolted to the upper side of the horizontal leg of the upper cross member 110 are two coupling prong receiving sockets 114, spaced laterally complementarily to the coupling prongs 40. Each of the prong receiving sockets 114 has in it, in exact correspondence with the prongs 40, an open ended seat 115 with a chamfered wall flaring outwardly downwardly at the same angle as the taper of the conical portion 42 of the prongs 40. The diameter of the upper opening in the tapered seats 115 is greater than the diameter of the upper ends of the prongs 40, but substantially less than the diameter of the prongs 40 at the cylindrical portion 41.

A latch plate 120 secured to and projecting from a square base provided with bolt holes, not here shown, is bolted to the web of the lower cross member 112 as indicated at 121 in FIG. 11. The latch plate 120, in this embodiment, extends vertically, parallel to the side rails 104 and 105, and is of a thickness to permit its sliding between the spaced latch walls 72. The latch plate 120 has a latch receiving hole 122 in it, adapted to be aligned with the holes in the latch walls 72 of the latch receiver 71.

Bolted to the underside of the lower cross member 112 is a step or toe plate 125, which projects rearwardly toward the coupling frame, and is positioned to extend closely beneath the bottom beam 32 when the coupling mechanism is fully coupled, to cage the coupling frame 30 between the prong receiving sockets 114 and the toe plate 125.

In the particular embodiment shown in FIG. 2, the implement frame 103 is mounted at its lower end on stanchions 130, and at its upper end on a post 131, by means of a yoke 132. The stanchions 130 and the post 131 are securely fastened to the dozer blade 101. In this embodiment, the stanchions 130 serve both to fasten the implement frame to the dozer blade, and also to serve as a supporting stand for the blade.

In the operation of the coupling mechanism of FIGS. 1 and 2, hydraulic fluid is admitted to the upper ends of the cylinders 62 to cause the pistons 64 to retract to the position shown in FIG. 1. Hydraulic fluid admitted to the left side, as viewed in FIG. 8, of the latch pin cylinder 77 causes the piston rod 76 to retract, bringing the latch pin 75 to the position shown in FIG. 8. Their height from the ground being set by the stanchions 130, the sockets 114 of the implement frame 103 are vertically above the tops of the prongs 40. While the grader coupling frame 30 is always oriented in a generally vertical, as distinguished from horizontal, direction, in the condition shown in FIG. 1, thanks to the fact that the upper links 50 are longer than the lower links 55, the upper part of the grader coupling frame 30 slants forward. The implement frame 103, on the other hand, is mounted to slant rearwardly, which insures that the latch plate 120 does not strike any part of the latching mechanism 70 when the grader coupling frame 30 is maneuvered below the sockets 114. The grader is moved forward until the prongs 40 are aligned with the seats 115 in the sockets 114. Hydraulic fluid is then admitted to the lower end of the cylinders 63, causing the pistons 64 to move upwardly and to rock the grader coupling frame 30 around the pivot points of the links 50 and 55. The links 50 are nearly enough horizontal so that the upward movement of the grader coupling frame 30 does not tend to move the prongs 40 back enough to make seating of the prongs 40 in the seats 115 difficult. Continued upward movement of the grader coupling frame 30 causes the conical section 42 of the prongs 40 to engage tightly the flaring surface of the seats 115, to swing the lower end of the frame 30 forwardly and to raise the implement 101 from the ground, tending to swing the implement toward the grader, and causing the latch plate 120 to enter the space between the latch walls 72. It also causes the toe plate 125 to move beneath the bottom beam 32. Hydraulic fluid is admitted to the right side of the latch pin cylinder 77 as viewed in FIG. 8 causing the latch pin to move through the holes in the latch walls 72 and the hole 122 in the latch plate 120, securely connecting the implement 101 to the grader.

The fact that the sockets 114 are bolted to the cross-member 110, the latch plate 120 is bolted to the lower cross member 112, and the toe plate 125 is bolted to the lower cross member 112 permits for easy and positive adjustment, by means of shims, of the relative positions of the sockets, latch plate and toe plate with respect to one another and with respect to the prongs 40, latch receiver 71 and bottom beam 32 of the moveable grader coupling frame 30. Initially, to compensate for any variation in the taper of the coupling prongs or the size of the seats 115, the implement can be coupled and the vertical position of the latch plate 120 and the toe plate 125 with respect to the latch receiver 71 and the lower beam 32 respectively can be determined. If the latch plate hole 122 is high with respect to the holes in the latch walls 72, the prongs 40 can be withdrawn, the sockets 114 unbolted and an additional shim can be inserted. If the toe plate 125 is high or low with respect to the bottom beam 32, it can be shimmed one way or the other to give a close fit. The adjustment, once made, will insure a tight connection until, after much use, there is wear between the prongs 40 and the sockets 114. The wear can be compensated by reshimming, to lower the sockets 114 or either of them.

Both the operation and the shimming arrangement can be seen clearly in the slightly different embodiment shown in FIG. 3. The grader assembly of this embodiment is substantially the same as the grader assembly shown in FIG. 1, and the same reference numerals are used to indicate the various elements. In this embodiment, tie plates 51 and 52 are welded to and between the upper links 50, and tie plates 56 and 57 are welded to and between the lower links 55 to lend rigidity to the grader assembly.

In the embodiment of coupling mechanism shown in FIG. 3, an implement assembly 302 with an implement frame 103 substantially the same as that shown in FIG. 2, is connected to a snow plow 301 by means of an attachment structure which forms no part of the present invention, but which provides four mounting tongues 305 to which the ends of the side rails 104 and 105 are attached in any suitable way. The reference numerals applied to the implement frame 103 are the same as those applied to the implement frame 103 of FIG. 2. In FIG. 3, socket shims 116 are shown between the upper cross member 110 and the underside of the sockets 114 which in FIG. 3 are shown as being made up of double plates, for the purpose of additional strength and thickness. Latch plate shims 123 are shown between the latch plate 120 and a vertical web 113 of the lower cross member 112. Toe plate shims 126 are shown between a sole plate part 117 of the lower cross member 112 and the toe plate 125.

In the coupled working condition shown in full lines in FIG. 3, the grader coupling frame has moved from the position shown in FIG. 1 at which the upper end of the grader coupling frame leans forward, to one in which it is substantially vertical or tilted slightly rearwardly. As indicated in broken lines, in order to lift the implement from the ground, for transportation or other purposes, the piston 64 is extended further, rocking the grader coupling frame around the pivots of the links 50 and 55 to raise the coupling frame and tilt the upper part of the frame rearwardly. As can be seen in FIG. 3, at the uppermost position, the upper beam 31 rests against a stop 8 secured to the bolster plate 2.

In all of the embodiments, if downward pressure is to be applied to the implement, the piston 64 can be retracted, which tends not only to move the grader coupling frame downwardly but to tilt it forwardly at the top. The latter force is transmitted through the prongs 40, while the downward force is delivered through the latching mechanism and latch plate and particularly through the bottom beam and toe plate.

Referring now to FIGS. 4, 5 and 6, for another embodiment of moveable grader coupling frame, reference numeral 430 indicates the coupling frame. The elements of the frame common to the embodiments shown in FIGS. 1 and 3 are indicated by the same reference numerals. The grader coupling frame 430 is connected to a bolster plate which is the same as the one shown in FIG. 10, except that the clevis ears 20 are separated into two distinct pairs, and spaced to be aligned with clevis ears 445 on the top beam 31.

In this embodiment, a latching mechanism 470 includes a latch receiver 471, with spaced side blocks 472 welded to the top surface of the bottom beam 32 and a top plate 473 spanning between and welded to the upper surface of the side blocks 472. A latch pin bearing sleeve 474 is welded to the top of the top plate 473 concentrically with an opening in the top plate 473. A cylindrical latch pin 475 is slidably mounted in the sleeve 474 and connected at one end to a rod 476, which extends through aligned holes in the upper and lower walls of the top beam 31. A compression spring 477 around the rod 476 is caged between a collar 478 on the rod and the underside of the top beam 31. The upper end of the rod 476, which projects above the upper surface of the top beam 31, is provided with an eye by which it is pivotally connected to a rocker type over-centering cam 480, provided with a handle 481. It can be seen that if the handle is moved clockwise as viewed in FIG. 5, the rod 476 will be pulled up against the bias of the spring 477, pulling the latch pin 475 clear of opening defined by and between the side blocks 472 and the facing surfaces of the top plate 473 and bottom beam 32. The flat on the right side of the cam as viewed in FIG. 5 will hold the cam and rod in retracted position. As is evident, the latch receiver 471 is designed to accommodate a latch plate extending parallel with the upper surface of the bottom beam 32 rather than perpendicular to it.

An implement frame adapted to use with the coupling frame 430 is shown in FIG. 7. Referring to FIG. 7 for another embodiment of implement assembly, an implement assembly 702 is mounted on a bucket 701. In this embodiment, an implement frame 703 is welded directly to a back wall of the bucket. The implement frame includes side rails 704 welded to the bucket and connected to one another by a sole plate 705, an upper cross member 710 and lower cross member 712. The cross members 710 and 712 are in the form of angles. A pair of sockets 714, with seats 715 extending through them are identical with the sockets of the embodiment shown in FIG. 3. They are bolted to the top surface of a leg of the upper cross member 710 with shims 716 between them. A toe plate 725 is bolted to the lower cross member 712, with shims 726 between them. In this embodiment, a latch plate 720 is bolted to an upstanding leg of the lower cross member 712, with shims 723 between them. The latch plate 720 can be identical with the latch plate 120 of the embodiments shown in FIGS. 1 and 3, but it is mounted at right angles to the latch plate 120, so that an opening 722 in the latch plate 720 extends in a direction parallel with the seats 715, rather than at right angles to them. When the implement assembly 702 is picked up by the grader coupling frame 430, the latch plate 720 moves into the opening in the latch receiver, and the handle 481 is then moved counterclockwise as viewed in FIG. 5 to permit the bias of the spring 477 to force the latch pin 475 through the opening 722 in the latch plate 720.

In all of the embodiments, which are substantially the same in general construction and identical in principle of operation, the prongs are preferably made harder than the sockets. The provisions of a heavy back plate on the bolster assembly is important because the bolster plate of most graders is relatively small, on the order of 12 to 24 inches wide, which means that the lateral support against twisting and bending of the bolster plate frame is provided by the back plate. As has been indicated, the back plate 16 is bent, and the side rails 17 and 18 are welded to the back plate, which provides the necessary rigidity and strength. The spacing of the plates 19 and 29 making up the side rails 17 and 18 of the bolster plate frame and of the side rails 33 and 34 of the grader coupling frame is a matter of choice. It is clear that in the embodiment shown in FIGS. 8 and 10, the links 50 and 55 will have relatively narrow bearing areas at their grader coupling frame end. In this embodiment, this permits the internesting of a part of the rails in the uppermost position of the moveable grader coupling frame, but other means can be used for providing desired clearances.

Numerous variations in the construction of the coupling mechanism of this invention, within the scope of the appended claims, will become apparent to those skilled in the art in the light of the foregoing disclosure. Merely by way of example and not of limitation, while the tapered prongs 40 are preferred, because of their self-tightening characteristics, hemispherical type prongs, of the character of the prong illustrated in my application Seer. No. 492,044, being filed concurrently herewith, may be used and sockets, with concave seats to receive the prongs, and with downwardly divergently inclined walls to make their insertion easier, also as shown in my said co-pending application, can be used. While a hydraulically operated latch pin mechanism is shown in the embodiment of FIGS. 1, 3 and 8, a mechanical arrangement such as shown in the embodiment of FIG. 5, or electrical or pneumatic latching mechanisms can be used. Similarly, hydraulic, pneumatic or electrical mechanisms can be used in place of the manual latching mechanism of the embodiment shown in FIG. 5. Pneumatic or electric mechanisms can be substituted for the hydraulic cylinder-piston assemblies 60. Other adjustment means can be employed both in respect of the elements of the implement assembly, and also of the elements of the grader assembly. For example, the prongs can be screwed into or otherwise mounted on the top beam in such a way as to permit their being moved axially when desired, for adjustment. The latch receiver of either the embodiment shown best in FIG. 8 or that shown in FIG. 5 can be mounted by means of bolts, for example, to permit both lateral and lengthwise adjustment to be made. The bolster plate frame itself can be mounted on the bolster plate by means of clamps or by welding or otherwise securing it. The bolster plate frame can be welded or otherwise secured directly to the grader chassis. These variations are merely illustrative.

Claims

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A coupling mechanism for connecting a motor grader to and disconnecting it from an implement, comprising a grader assembly including a bolster plate frame and means for mounting said bolster plate frame to the chassis of said motor grader, a moveable grader coupling frame supported on said bolster plate frame, said grader coupling frame extending in a generally vertical direction and having upper grader coupling means, power means, supported on said bolster plate frame and connected to said moveable grader coupling frame, guide means for guiding said upper grader coupling means part of said moveable grader coupling frame in two directions, outward from and upward with respect to said bolster plate frame when said implement is being connected and downward with respect to and inward toward said bolster plate frame when said implement is being disconnected, and moveable grader latching means carried by said moveable grader coupling frame at a position spaced from said upper grader coupling means, and an implement assembly mounted on said implement, said implement assembly including an implement frame having upper implement coupling means complementary to the upper grader coupling means and implement latching means complementary to the grader latching means.

2. The coupling mechanism of claim 1 wherein the grader assembly is a demountable, self-contained unit, adapted to be mounted on a bolster plate fixedly mounted on the grader chassis.

3. The coupling mechanism of claim 1 wherein the grader coupling frame has a top beam and the upper grader coupling means includes two, spaced prongs mounted on and projecting upwardly from said beam.

4. The coupling mechanism of claim 3 wherein the upper implement coupling means includes sockets and means associated with said sockets for selectively varying the vertical distance of said sockets from said implement latching means.

5. The coupling mechanism of claim 1 wherein the grader coupling frame has a bottom beam and the implement frame includes a toe plate projecting from said implement frame beneath the said bottom beam when the grader coupling frame and implement coupling frame are coupled.

6. The coupling mechanism of claim 5 wherein means are associated with said toe plate for selectively varying the vertical distance of the toe plate with respect to the bottom beam.

7. The coupling mechanism of claim 3 wherein the said power means includes at least one hydraulic cylinder-piston assembly one end of which is pivotally mounted at a lower part of said bolster plate frame and the other end of which is pivotally mounted on said top beam.

8. The coupling mechanism of claim 7 wherein the said guide means comprise two pairs of links, an upper pair and a lower pair, the links of said upper pair being longer than the links of said lower pair, one end of each of said links being pivotally mounted on said bolster plate frame and the other end, on said moveable grader coupling frame, the pivot axes of the links on the coupling frame being spaced apart vertically farther than the axes of the links on the bolster plate frame.

9. The coupling mechanism of claim 8 wherein the pivot axis of the ends of the lower pair of links on the bolster plate frame is forward of the pivot axis of the ends of the upper pair of links on the bolster plate frame.

10. The coupling mechanism of claim 9 wherein the links of the said two pairs of links are high vertically compared with their width laterally.

11. The coupling mechanism of claim 8 wherein the length of the longer of the links is less than the vertical spacing of the pivot axes on the grader coupling frame.

12. A coupling mechanism for connecting a motor grader to and disconnecting it from an implement, comprising a grader assembly including a bolster plate frame and means for fixedly mounting said bolster plate frame on a bolster plate fixedly mounted to the chassis of said motor grader, said bolster plate frame having a back plate, spaced parallel side rails and spaced clevis ears on the lower part of said back plate positioned laterally between the said side plates;

a moveable grader coupling frame supported on said bolster plate frame, said grader coupling frame being generally rectangular in front elevation, having heavy top and bottom generally horizontal cross beams, said grader coupling frame extending in a generally vertical direction;

clevis ears oppositely disposed from the bolster frame clevis ears carried by said top beam;

two, spaced, cone-shaped coupling prongs mounted on said top beam with their smaller ends projecting upwardly therefrom;

hydraulic cylinder-piston assemblies pivotally connected to and extending between said oppositely disposed clevis ears;

upper and lower pairs of links pivotally mounted at one end on the bolster plate frame side rails and at their other end on said grader coupling frame, the upper of said pairs of links being longer than the lower of said pairs and the vertical spacing of the pivot points of said links on the grader coupling frame being greater than the vertical spacing of the pivot points of said links on the said bolster frame side rails, said upper links being shorter than the vertical spacing of the pivot points of the links on the said bolster frame side rails; and

a latching mechanism carried by the grader coupling frame and comprising a latch pin, journaled for reciprocating movement, and means for reciprocating said pin;

and an implement assembly mounted on said implement, said implement assembly including an implement frame having coupling prong receiving sockets with openings of a diameter larger than the smaller ends of the conical prongs of the grader coupling frame but smaller than the diameter of a projecting portion of the conical prongs closer to the top beam of the grader coupling frame, said sockets being positioned vertically and laterally to receive said prongs;

a latch plate having a hole therein of size and position to receive the latch pin of the grader coupling frame and a toe plate along a lower part of the implement frame positioned to project closely beneath the bottom cross beam of the grader coupling frame when the implement and grader frames are coupled.

13. The coupling mechanism of claim 12 wherein the prong receiving sockets are removably mounted on the implement frame and adapted to accomodate shims between the implement frame and prong receiving sockets, and the toe plate is removably mounted on the implement frame and adapted to accomodate shims between the toe plate and the implement frame.

14. The coupling mechanism of claim 12 wherein the said bolster frame side rails are made up of parallel plates secured to said back plate, the grader coupling frame has side rails including spaced parallel side plates, and the bolster plate side rails are narrower than the grader coupling frame side rails.

15. The coupling mechanism of claim 12 wherein the lower part of said bolster frame back plate is bent forwardly and the pivot points of the lower pair of links on the bolster frame side rails are forward of the pivot points of the upper pair of links on the bolster frame side rails.