US3591935A

US3591935A - Earth moving equipment

Info

Publication number: US3591935A
Application number: US746594A
Authority: US
Inventors: Mark H Bremmer; Albert R Hiler
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-07-22
Filing date: 1968-07-22
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13

Abstract

A lever gudgeon and connector block between earth-contacting mechanism and the lifting arms of a prime mover permits the earth-contacting mechanism to be pivoted at different angles both horizontally and vertically to such lifting arms for performing various operations without moving the prime mover, which block extends between the lifting arms providing a lever with extensive mechanical advantage and, also, permits horizontal, diagonal, and vertical pivoting of the earth-contacting equipment as attachments to the lifting arms without binding or impingement thereof.

Description

United States Patent [72] Inventors Mark H. Bremmer 145 Garland St.; Albert R. Hiler, 145 Holland St., both of Denver, Colo. 80226 [21] Appl. No. 746,594

[22] Filed July 22, 1968 [45] Patented July 13, 1971 [54] EARTH MOVING EQUIPMENT 3 Claims, 14 Drawing Figs.

[52] US. Cl 37/1l7.5, 37/118,172/805,172/806 [51] Int. Cl E02i 3/85 [50] Field oISearch 37/1175, l18;172/801, 804, 805, 806; 214/768 [56] References Cited UNITED STATES PATENTS 1,195,271 8/1916 Ruth 172/806 X 1,457,878 6/1923 Hopfield 172/806 X 2,402,352 6/1946 Taylor 172/806 2,684,163 7/1954 Boulton 37/1175 X FOREIGN PATENTS 721,011 11/1965 Canada 172/806 873,189 3/1942 France 37/1175 Primary E.raminerRobert E. Pulfrey Assistant ExaminerAlan E. Kopecki Attorney-Richard D. Law

ABSTRACT: A lever gudgeon and connector block between earth-contacting mechanism and the lifting arms of a prime mover permits the earth-contacting mechanism to be pivoted at different angles both horizontally and vertically to such lifting arms for performing various operations without moving the prime mover, which block extends between the lifting arms providing a lever with extensive mechanical advantage and, also, permits horizontal, diagonal, and vertical pivoting of the earth-contacting equipment as attachments to the lifting arms without binding or impingement thereof.

PAIENTEnJuu 3m: 359L935 SHEET 1 [IF 4 INVEN'IURS MARK H. BREMMER BY ALBERT R. H/LER fiat/M03 A T TOR/V5 Y PATENTEnJuualsn 3591.935

' sum u UF 4 INVk/(IHVS MARK H. BREMMER ALBERT R. H/LER EARTH MOVING EQUIPMENT Earthcontacting equipment of various types, and more particularly dozer blades and loader buckets have been used extensively with crawler-type prime movers, and more recently with various types of rubber-tired vehicles as the prime movers. Such equipment usually includes a pair of lifting arms, one end pivotally mounted on each side of the vehicle and extending forwardly thereof for connection with an earth-contacting mechanism, such as a dozer blade, loading bucket, etc. One application of the use of the lifter arms with an earth-contacting mechanism, shown in the Boultens US. Pat. No. 2,684,163, patented July 20, 1954, converged the ends of the lifter arms together. Thence a small cubical gudgeon is mounted on its horizontal axis the space between the end of the arms, and the earth-contacting equipment is mounted on the vertical pivot passing through the gudgeon. Powering the pivotal movements of the earth-contacting equipment by means of hydraulic cylinders, the contacting mechanism was made to pivot horizontally. No powered vertical movement has been available. The arrangement requires that the gudgeon be attached in a linear, parallel relationship to the frame of the vehicle which restricts the vertical and horizontal movement of the earth-contacting equipment.

According to the present invention we have provided improvements which in concept is a system commencing at the attachment points on the vehicle lifter arms, whereby the structure supporting the lever gudgeon is a distinct structural element-supporting stress and torque forces. Attached to supporting structure in a pivotal relation is a lever gudgeon connecting block. In turn attached thereto are two earth-contacting equipment-supporting structures, one specific form being a function within and upon itself, and in another, in similar function, as an integral part of the earth-contacting equipment structure. Additionally the connector device provides lateral stability of the lifter arms in vertical and horizontal movements of the earth-contacting equipment thereby applying an equalized load on the lifting arms and on the prime mover itself.

Included among the objects and advantages of the present invention is the provision of a connector device between the lifting arms of a prime mover and earth-contacting equipment which is arranged to provide variable dimensions for specific work load capabilities.

Another object of the invention is to provide a connecting device between the lifting arms of the prime mover and earthcontacting equipment which provides lateral stability for the lifting arms under torque applications.

A still further object of the invention is to provide a connector device for earth-contacting mechanism which is inclusive of motive power mechanisms for pivotal movements of the earth-contacting mechanism functionally, as well as being an integral part of the structure.

Another object of the invention is to provide arrangement for accurate coordination of the connector device movement and motive power therefor in leveling, rotating, tilting and static support functions of the related segments of the entire mechanism system which are performed without binding or impingement, automatically and/or with command function initiator operators, to related or independent motive devices.

Yet another object of the invention is to provide connector means between lifting arms of a prime mover and earth-contacting equipment which is readily accommodated to the arms of the prime mover and the earth contacting equipment itself.

These and other objects and advantages of the present inention may be readily ascertained by referring to the following description and appended illustrations in which:

FIG. I is an exploded view of the parts of a connector device according to the invention, illustrating attachment means of a clevis portion for a loader bucket assembly;

FIG. 2 is a perspective view, of a dozer blade incorporating a connector means for the lifting arms of a prime mover, according to the invention;

FIG. 3 is a side elevational, partially cut away, view of the ends of lifting arms of a prime mover, according to the invention;

FIG. 4 is a side elevation, detail of a connector clevis yoke for a lever gudgeon for attachment of a loader bucket to lifter arms of a prime mover, according to the invention;

FIG. 5 is a side elevation, detail of a connector clevis yoke for a lever gudgeon for attachment of a dozer blade, according to the invention;

FIG. 6 is a top plan view of one type of connector means between an earth-contacting mechanism and the lifter arms of a prime mover, illustrating the structure of the motive power means for movements of the lever gudgeon, and attached bucket or dozer blade;

FIG. 7 is a top plan view of modified form of a connector means between an earth-contacting mechanism and the lifter arms of a prime mover, illustrating the structure of a motive power means for movements of the lever gudgeon, and an attached bucket or dozer blade;

FIG. 8 is a side elevational view of a quick disconnect, according to the invention, for connections between cylinder pistons and a movable member;

FIG. 9 is a perspective view of one form of connector means, according to the invention, mountable between the lifter arms of a prime mover;

FIG. 10 is a perspective view of a modified form of a connector means mountable between the lifter arms of a prime mover;

FIG. 11 is a fragmentary detail of one form of connector means, with a means for pivoting a lever gudgeon mounted between the ends of the lifter arms of a prime mover;

FIG. 12 is a fragmentary detail of a still further modified form of power means of pivoting a lever gudgeon according to the invention;

FIG. 13 is a fragmentary detail of a hydraulic rotary motor for pivoting a lever gudgeon according to the invention; and

FIG. 14 is a fragmentary detail of pivoting means for lifter arms of a prime mover that extend substantially horizontally outwardly from the prime mover utilizing a connector such as shown in FIG. 9.

The exploded assembly of FIG. 1 illustrates one form of a connector means according to the invention, as applied with the clevis structure to which a loader bucket assembly is attached. A bulldozer blade with attached clevis means, FIG. 2, is applied integrally without a separate clevis structure to the connector means. The entire connector structure is connected to lifter arms which extend at a downwardly angle from a pivot point on a prime mover. The entire connector structure may, also, be connected to lifter arms which extend forwardly in a linear manner from a pivot point on a prime mover, or at any angle from the prime mover.

The connector block for the lifter arms, FIG. 1, includes a generally square tubular section 10 provided with internal reinforcing crossed-ribs 11 preferably extending through the square tube. Attached to one side of the tube is a triangular tubular member 12. Reinforcing plates 14 extend outwardly from the triangular tube 12 supporting a pair of spaced-apart aperture plates 16 and 17 to provide means for permitting a lever gudgeon 20 to be pivotally mounted in the space between the two plates. The plates 16 and 17 extend rearwardly and over the square tube 10 to provide additional reinforcing for support of the lever gudgeon. A pivot pin 21, passing through the apertures in plates 16 and 17 and passage 22 in the lever gudgeon, mounts the lever gudgeon in the connector block and provides for pivotal movement around the pin 21. Upstanding apertured idler arms 24 pivotally mounted on ears 24a fixed to the connector block provide means for attachment of a lever arm with the upstanding ears 25 on the lever gudgeon. The arms 24 are pivotally mounted in ears 24a secured to the block 10. The lever arm, as described below, may be a power cylinder, a manually variable lever or other means arranged to provide pivotal movement of the lever gudgeon around the pivot pin 22.

A clevis member, shown in general by numeral 30, is arranged for pivotal attachment with the lever gudgeon, and provides means for attachment of earth-contacting equipment. The clevis includes an upright frame member 31 to which is attached rearwardly extending, spaced-apart ears 32 and 33 for telescoping over the front of the lever gudgeon, and both being apertured to receive a pivot pin 34 passing through the passage 26 in the lever gudgeon, which permits the clevis to pivot horizontally in relation to the lever gudgeon about the pivot pin 34.

A bucket 70 may be attached to the clevis, shown in FIG. 4 by means of pins 37 passing through holes in the lower portion of

support frame members

35 and 36, each of which includes a pair of spaced-apart plates, and a pair of reinforcing plates 72. This permits vertical pivotal movement of the bucket in relation to the lever gudgeon. This pivotal movement is powered by a pair of cylinders 47 mounted by pivot pins 48 through holes 49 at the upper part of the

support plates

35 and 36, attached to lever arms 39 pivotally mounted at one end to the support plates by pins 45 through holes 46 and to connecting rods 38 at the other end. Each connecting rod 38 is pivotally attached to a reinforcing plate 71 on the bucket 70. The cylinders are activated conjointly for pivoting the bucket.

A dozer blade with an integral clevis arrangement may be substituted for the clevis 30 and the bucket. The cylinders 47 are not needed with a dozer blade, and a pair of cylinders mounted between the lifter arms of a prime mover and the dozer blade permits the blade to be pivoted about a vertical pin.

FIGS. 2 and illustrate such a dozer blade which may be mounted on lever gudgeon 20 in lieu of clevis assembly 30. Primary attachment of the blade to the lever gudgeon is by mating of the clevis-type ears 320 depending from the rear of the blade above and below passage aperture 26 in the lever gudgeon and held in place by pin 34 thereof. The three-dimensional triangular support structures 73, also, attached to the rear of the dozer blade, are attached to piston rods 62 by their ball joints 64a. The cylinders of piston rods are not shown by are secured in conventional manner to the lifter arms or other supporting structure so as to pivot the blade about the vertical pin 34.

The connector block and lever gudgeon are shown attached to prime mover lifter arms in FIG. 3 wherein lifter arms 52 extend downwardly at a steep angle from a pivot point associated with power cylinders on the prime mover. The ends of the lifter arms need not be converged together since the block may be readily made to fit any unit. Connector block is welded or otherwise attached between the two spaced-apart arms with the aperture plates 16 and 17 extending forwardly thereof supporting a lever gudgeon on a pivot pin 21. A power cylinder 55 is attached to the pivot cars 24 and its piston rod 56 is attached to the cars 25. A Y-connector rod 57 connects the lever arms or cars 24 to a pivoted lever arm 58 pivoted at 59 on the lifting arms 52. This arrangement of the connector rod 57 pivotally mounted on pivoted

arms

24 and 58 form with the sidearms 52, in effect, a pantograph for controlling the angular position of the pivoted block 20 and therefore the position of an implement mounted on the pivotally attached clevis assembly 30. The lower end of the lever arm 58 is arranged to be attached to the prime mover, not shown, to provide a pantograph assembly for automatically maintaining the vertical position, or other predetennined position of the lever gudgeon as the lifting arms are raised or lowered. The position of the lever gudgeon as the lifting arms are raised or lowered. The position of the lever gudgeon may be, of changed in relation to the lifter arms by means of the cylinder 55, which on extension pivots the lever gudgeon forwardly and on retraction pivots it rearwardly. An outrigger power cylinder 60 on each side of the assembly is attached by means of a quick disconnect 61 to the top of the lever arm 58 and the piston rods 62 are attached by means of quick disconnects 63 to balls 64 on the clevis 30, or balls 64a on the dozer blade when attached to the lever gudgeon. The connection of the clevis 30 to the bucket 70 is shown in FIGS. 4 and 6, wherein the bucket is provided with the pair of vertical flanges 7 I apertured to accommodate a pivot pin for the end of the push-pull rod 38. Actuation of the cylinders 47 provides a dumping action or change of position of the bucket in relation to the lever gudgeon.

The connection between a dozer blade and the lever gudgeon according to the invention, is shown in FIGS. 2, 5, and 7 as explained above. Of course, the clevis must be removed, and the configuration of the connector block on the ends of lifter arms permits the bucket and/or dozer blade to be placed on the ground with the pressure taken off all the joints, so that the connecting pins, particularly the pivot pin 34, may be easily moved and the various earth contacting member removed or easily attached. The quick disconnects on the outrigger booms provide fast removal of the outrigger cylinders from the

balls

64 or 640. When the dozer blade is replaced by the clevis the quick disconnects are arranged to fit on the balls 64. When the dozer blade is in place on the lever gudgeon, the quick disconnects are attached to the ball coupling 64a mounted on rearwardly extending triangular structures 73 providing supports for the coupling balls 64a to the outrigger cylinders.

A bulldozer connection is illustrated in FIG. 7, which, also, shows a T-connector rod, replacing the Y-connector of FIG. 6. The T-connector is valuable where clearance is needed to accommodate some portion of the prime mover between the lifter arms. The Y-connector is useful where such clearance is not necessary.

The T-connector of FIG. 7 is mounted on lifter arms 52a, in cluding a connecting rod 65 on each side mounted by a ball joint 61a on upper idlers 58a and to lower idlers 240. A T-bar 67 is mounted across the end of the lifter arms secured in lower idlers 24a. A cylinder piston assembly 66 is mounted between the T-bar and the lever gudgeon 20 which is pivotally mounted in a main frame or connector block 10. The T-bar and connector provides a pantograph arrangement for maintaining the lever gudgeon and a carried earth contacting device at a predetermined angle from vertical, a type of leveling mechanism for the earth-contacting device.

As the lifter arms of various types of prime movers extend forwardly from the prime mover at different configurations and angles in relation to the prime mover, the connector block between the two lifter arms must be varied to accommodate such configuration angle. As shown in FIG. 9 one form of the connector block is made with a square tube 76 provided with crossed reinforcing members 77 extending therein, and reinforcing triangular members 78 are mounted on the ends of the tube extending forwardly supporting

apertured plates

79 and 80. The

plates

79 and 80 extend rearwardly and over the tube 7 6, to provide additional reinforcing for the tube. Such a connector block is useful where the arms extend essentially horizontally forwardly of the prime mover. As shown in FIG. 14 the arms 120 extend forwardly and, in lowered position, substantially horizontal. The connector block is welded or otherwise attached between the pair of arms extending forwardly of the prime mover, and a lever gudgeon is mounted on a pivot pin 21 in the space between the

plates

79 and 80. A cylinder 12] and its piston rod 124 provides means for pivoting the lever gudgeon 30 about the pivot pin 21 mounted on the connector block.

A modified fonn of the connector block is shown in FIG. 10, wherein a square tube 83, having crossed reinforcing members 84, is provided with a triangular tube welded to one side thereof, and reinforcing triangular-shaped plates 86 extend forwardly thereof supporting apertured plates 87 into which a lever gudgeon is pivoted. The plates 87 extend rearwardly providing additional support for the tubes. The reinforced tubular construction provides a very lightweight, strong and rigid connector block which is arranged to withstand the forces transmitted to earth-contacting equipment by the prime mover and the various motive power means moving the earthmoving equipment.

In the modification shown in FIG. 11 a prime mover (not shown) is provided with lifter arms 90 extending downwardly at an angle to the ground. The lower part of the lifter arms rest on the ground and a connector block 83 is welded or otherwise secured across the ends of the lever arms with the pivot plates 87 extending forwardly thereof supporting a lever gudgeon by means of pivot pin 21. A clevis yoke 32 is mounted by means of a pivot pin 34 to the lever gudgeon providing means for supporting either the clevis or the dozer blade 40. A power cylinder 91 has its piston 92 connected to pivoted S-bar which is attached by means of a push-pull rod 94 to the ears of the lever gudgeon. Actuation of the cylinder 91 provides means for pivoting the lever gudgeon in relation to the lifter arms.

A slightly modified form of pivotal means for the lever gudgeon as shown in FIG. 12, where lifter anns 100 with attached connector block 83 extending downwardly from a prime mover are provided with a support frame 102 which pivotally supports a power cylinder 101 generally centrally thereof in a pivot saddle 103, so that the piston rod 104 may be attached to the ears 25 of the lever gudgeon by means of a pivot pin 105 for pivoting the lever gudgeon in relation to the lifter arms.

A further modified form for pivoting a lever gudgeon mounted on a connector block between the ends oflifter arms is illustrated in FIG. 13, wherein lifter arms 111 each having a toe 112 is provided with a connector block attached therebetween. A rotary hydraulic motor 113 is mounted on a support plate 114 secured between the two arms. The motor 113 turns a worm 115, which in turn turns a worm wheel 116 pivotally attached to a lever gudgeon 117. This provides pivotal relationship between the gudgeon 117 and the prime mover arms 11].

In the form as shown in FIG. 14, lifter arms 120 extend forwardly from a lower point of attachment on a prime mover and are secured together by means of the connector block 77 welded or otherwise secured to the ends of the lifter arms. The apertured plate 79 and its mate 80 extends forwardly so that a lever gudgeon may be secured thereto by means of the pivot pin 21. A power cylinder 121 is pivotally secured to a pivoted lever arm 122, mounted by means of a pivot pin 123 to the connector block 76 which provides means for changing the angular position of the lever gudgeon 30 in relation to the lifter arms 120. This arrangement, also, provides means for attaching the same to a Y-lever arrangement such as 57 in FIG. 6 to provide a pantograph for leveling arrangement for the earth-contacting device, as by the arm 122 pivotally connected to a connector rod such as rod 57, providing a configuration such as shown in FIG. 3. A piston rod 124 is pivotally connected to the cars 25 on the lever gudgeon, and the cylinder provides means for changing the angle of the lever gudgeon.

A form of a quick disconnect means between the piston rods of a cylinder and a movable member of the connector means is illustrated in FIG. 8 wherein a piston rod 140, which may be the piston rod of any of the cylinders connected to various movable members, and which may be desired to be disconnected from the unit. The quick disconnect is a bolt held connector means to a ball 142 mounted on a rod mount 143 which may be attached to a movable unit or member. The rod 140 is attached to a head member 141 by means of bolts 150 passing through holes in a pair ofsleeves 147 passing over an irregular joint line 148. The double sleeve arrangement is for strength, however, a single sleeve may be used. Thisjoint is easily taken apart by removing the bolts 150, sliding the sleeves 147 along the shaft 140 and then lifting the irregular joint apart. The head 141 has a semicircular recess 144 therein and bottom casting 145 has a portion of a hemispherical opening therein arranged to be bolted by means of bolts 149 to the head 141 for containing the ball 142 in the head. Thus by attaching the ball-holding head on the ball members of either the clevis or the dozer blade, the cylinders may be quickly disconnected or connected by means of the two bolts 1150 holding the irregular joint. This quick disconnect and removal of the vertical pin 34 provides a sim le and easy means of changing the earth-contacting equipment on the connector block and lever gudgeon. Furthermore, as pointed out above the connector block is so arranged that when the lever arms are in down position with the earth-contacting equipment resting on the ground all the weight is removed from the vertical pivot pin 34 so that it may be easily removed from the earth-contacting equipment.

The geometry of the connector block or main frame which is secured to the ends of the lifter arms permits the lever gudgeon to pivot through a substantial vertical angle about the pivot pin 21. Additionally, the frame or connector block permits substantial horizontal pivoting of the earth-contacting equipment about the vertical pivot pin 34, and this is approximately 45 to each side of the main frame. This wide angle of turning permits the loading of a truck without turning the prime mover and permits unloading of the bucket at an angle, depending upon the relative position of the lever gudgeon. Since different types of prime movers have different types of lifter arms the connector block of the present invention is readily adaptable to the lifter arms, with the lever gudgeon providing the same function.

While the invention has been illustrated by reference to particular devices, there is no intent to limit the spirit or scope of the invention so set forth, except as defined in the following claims.

We claim:

1. An assembly with a comprising:

a. connector block means includes a reinforced rectangular tube having its ends rigidly secured adjacent the ends of said lifter arms;

b. a triangular tube rigidly secured to an outward facing side of said rectangular tube inclusive of depending horizontal pivot means for a lever gudgeon extending forwardly of said triangular tube to mate with said lever gudgeon and arranged with said horizontal pivot means in a substantially parallel position to the ground when said lifter arms are resting on or near the ground;

c. a lever gudgeon mounted on said horizontal pivot means, said lever gudgeon including vertical pivot means for supporting earth-contacting means;

(I. first actuator means pivotally connected between said lever gudgeon and said lifter arms for pivoting said lever gudgeon about said horizontal pivot means thereby pivoting said vertical pivot means and a carried earth-contacting means through a vertically disposed are;

e. second actuating means mounted between said earthcontacting means and said lifter arms for moving carried earth-contacting means through a horizontal arc; and

f. earth-contacting means carried by said lever gudgeon.

2. An assembly according to claim 1 wherein said horizontal pivot means is a pair of spaced-apart apertured plates.

3. An assembly with a pair of lifter arms of a prime mover comprising:

a. connector block means rigidly secured adjacent the ends of said lifter arms inclusive of horizontal pivot means for a lever gudgeon extending forwardly of said connector block means, said connector block means arranged with said horizontal pivot means in a substantially parallel position to the ground when said lifter arms are resting on or near the ground;

. a lever gudgeon mounted on said horizontal pivot means, said lever gudgeon including vertical pivot means for supporting earth-contacting means for pivotal movement about said vertical pivot means;

c. idler arms pivotally mounted on said connector block;

d. a pair of pivot levers pivotally mounted on said lifter arms;

e. a connecting rod assembly connected between said idler arms on said connector block and said pivot levers;

pair of lifter arms of a prime mover horizontal arc; and

h. earth-contacting means carried by said lever gudgeon on said vertical pivot means so that said earth-contacting means swings through a generally horizontal arc and so that the connected combination of pivot levers, lifter arms, idler arms and connecting rod provide a pantograph for leveling said lever gudgeon and carried earthcontacting means on raising and lowering said lifter arms.

Claims

1. An assembly with a pair of lifter arms of a prime mover comprising: a. connector block means includes a reinforced rectangular tube having its ends rigidly secured adjacent the ends of said lifter arms; b. a triangular tube rigidly secured to an outward facing side of said rectangular tube inclusive of depending horizontal pivot means for a lever gudgeon extending forwardly of said triangular tube to mate with said lever gudgeon And arranged with said horizontal pivot means in a substantially parallel position to the ground when said lifter arms are resting on or near the ground; c. a lever gudgeon mounted on said horizontal pivot means, said lever gudgeon including vertical pivot means for supporting earth-contacting means; d. first actuator means pivotally connected between said lever gudgeon and said lifter arms for pivoting said lever gudgeon about said horizontal pivot means thereby pivoting said vertical pivot means and a carried earth-contacting means through a vertically disposed arc; e. second actuating means mounted between said earth-contacting means and said lifter arms for moving carried earth-contacting means through a horizontal arc; and f. earth-contacting means carried by said lever gudgeon.

3. An assembly with a pair of lifter arms of a prime mover comprising: a. connector block means rigidly secured adjacent the ends of said lifter arms inclusive of horizontal pivot means for a lever gudgeon extending forwardly of said connector block means, said connector block means arranged with said horizontal pivot means in a substantially parallel position to the ground when said lifter arms are resting on or near the ground; b. a lever gudgeon mounted on said horizontal pivot means, said lever gudgeon including vertical pivot means for supporting earth-contacting means for pivotal movement about said vertical pivot means; c. idler arms pivotally mounted on said connector block; d. a pair of pivot levers pivotally mounted on said lifter arms; e. a connecting rod assembly connected between said idler arms on said connector block and said pivot levers; f. first actuator means pivotally connected between said lever gudgeon and said idler arms on said connector block for pivoting said lever gudgeon about said horizontal pivot means thereby pivoting said vertical pivot means and carried earth contacting means through a vertical arc; g. second actuating means mounted between said earth-contacting means and said prime mover lifter arms for moving carried earth-contacting means through a horizontal arc; and h. earth-contacting means carried by said lever gudgeon on said vertical pivot means so that said earth-contacting means swings through a generally horizontal arc and so that the connected combination of pivot levers, lifter arms, idler arms and connecting rod provide a pantograph for leveling said lever gudgeon and carried earth-contacting means on raising and lowering said lifter arms.