US3266179A

US3266179A - Digging attachment

Info

Publication number: US3266179A
Application number: US304079A
Authority: US
Inventors: Norman R Golden
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-08-23
Filing date: 1963-08-23
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

g- 16, 1966 N. R. GOLDEN 3,266,179

DIGGING ATTACHMENT 2 Sheets-Sheet 2 Filed Aug. 25, 1965 I 1 If mun III! II me we #4 #0 rss 1 INVENTOR L /lbw) j, A W

ATTORNEY NORMAN R. GOLDEN United States Patent 3,266,179 DEGGENG ATTACHMENT Norman R. Golden, 531 S. Broad, (Iariinville, lili. Filed Aug. 23, 1963, Ser. No. 304,079 2 Claims. (til. 37-456) This application is a continuationdn-part of my prior co-pending application Serial No. 130,865 filed August 11, 1961 and now abandoned.

This invention relates to improvements in trenching apparatus and more particularly, but not by way of limitation, to a digging attachment adapted for utilization with a tractor or the like.

At the present time, many pipe lines, power transmission cables and the like are being laid underground or buried in lieu of the previous overground or above ground installations therefor. As a result, there is an increasing demand for trenches or ditches for burying the lines, and the trenches must normally extend substantially continuously over great distances and through variable or adverse terrain conditions. The digging of these long, uninterrupted trenches, and particularly over rough ground or through mountainous regions, is difiicult with presently available equipment. It is usually necessary to advance or move the digging vehicle substantially continuously during the digging or tranching operation in order to provide a trench of the desired length. Each obstacle encountered by the vehicle normally requires a divergence thereof and results in a crooked path for the ditch being dug. For example, a vehicle moving along a highway or the like for digging a trench adjacent thereto usually must be driven or moved around each culvert or the like, thus interrupting the digging operation, or requiring the digging of an off-set portion in the trench in order to by-pass the culvert. In addition, the digging of long and continuous trenches through hilly or mountainous areas is dimcult in that the vehicle can normally dig only a relatively short distance independently of the movement of the digging vehicle. Thus, the vehicle must be moved through or over the hills and valleys in order to dig the trench, and often the adverse condition of the terrain is extremely difficult to traverse in the vehicle.

The present invention contemplates a novel digging o1 trenching attachment for a vehicle, such as a farm tractor, backhoe, or the like, wherein a long and continuous trench may be dug efiiciently and rapidly through substantially any desired area. The novel digging attachment is particularly designed and constructed for simplicity of operation, and facilitates the digging of a continuous trench 'by enabling the digging operation to be extended through a much greater distance independent of the movement of the vehicle. This is a particular advantage in the digging of long continuous trenches in mountainous terrain in that the vehicle may be disposed at a convenient location and the trench may be dug a considerable length without moving the vehicle. Furthermore, the novel digging attachment is of a universal type construction wherein a trench may be dug continuously with substantially no oil-set portions, regardless of obstacles which the tractor may encounter. The novel digging attachment is simple and efficient in operation and economical and durable in construction.

It is an important object of this invention to provide a novel digging attachment for vehicles for facilitating the digging of long and substantially continuous trenches, regardless of the condition of the terrain.

It is another object of this invention to provide a novel digging attachment for a vehicle wherein a trench may be dug through an extended length independently of the movement of the vehicle.

Another object of this invention is to provide a novel digging attachment for a vehicle wherein a long and continuous trench may be dug regardless of substantially any obstacle encountered by the vehicle.

Still another object of this invention is to provide a novel digging attachment for a vehicle particularly designed and constructed for simplicity of operation.

A further object of this invention is to provide a novel digging attachment for a vehicle having a universal type construction wherein a trench may be dug in substantially any direction with respect to the vehicle.

A still further object of this invention is to provide a novel digging attachment which may be readily adapted for use with substantially any suitable vehicle, such as a farm tractor, backhoe, or the like.

Other objects and advantages of the invention will be evident from the following detail description, read in conjunction with the accompanying drawings, which illustrate my invention.

In the drawings:

FIGURE 1 is a rear elevational view of a backhoe type vehicle provided with a digging attachment constructed in accordance with one embodiment of this invention and showing in dotted lines the main boom of the backhoe vehicle in a somewhat lowered position.

FIGURE 2 is a side elevation of a digging attachment in accordance with the embodiment shown in FIGURE 1.

FIGURE 3 is a fragmentary elevational view of a portion of a digging attachment similar to that shown in FIG- URE 2 and illustrating the drive means for the upper sprocket member and the clearance provided for this sprocket member.

FIGURE 4 is a fragmentary side elevation of a digging attachment constructed in accordance with another embodiment of this invention and showing a modified means for rotating one portion of the digging attachment with respect to the other.

FIGURE 5 is a fragmentary plan view of the embodiment shown in FIGURE 4.

FIGURE 6 is a fragmentary sectional view taken along section line 66 of FIGURE 5.

Referring to the drawings in detail, reference character 19 generally indicates a backhoe vehicle having the usual main boom 12 extending outwardly therefrom. It is to be understood that the invention is not limited to utilization with a backhoe vehicle, but may he used with substantially any tractor type vehicle, such as the well known farm tractor, or the like. The boom 12 is usually carried by an upright member 14 which is pivotally secured to the vehicle 19 by a rotatable shaft 16 having an outwardly extending flange 18 secured to the member 14. The member 14 may thus be rotated horizontally about the shaft 16, the latter constituting a substantially vertical axis. The boom 12 is normally pivotally secured to the member 14 in any well known manner (not shown) for pivotal movement in a vertical plane, and may be pivoted by any suitable control means (not shown) by the operator of the vehicle 10, for example, to the dotted line position shown in FIGURE 1. The outer extremity of the boom 12 is normally adapted for receiving a variety of attachments thereon, as will be hereinafter set forth, and the vehicle It) is usually provided with a hydraulic cylinder 22 having a reciprocal rod 24 extending axially therefrom for operation of the attachment carried by the boom 12.

A digging attachment, generally indicated at 26, com prises a first arm member 28 preferably open or bifurcated at one end portion for receiving the outer extremity 20 of the boom 12 therein. The arm 28 is preferably of a hollow construction, but not limited thereto, and is pivotally secured at 30 to the boom 12 in any suitable manner (not shown). The arm 28 extends upwardly beyond the boom 12 and is pivotally secured at 32 to the outer end of the rod or arm 24, as is well known. It will be readily apparent that reciprocation of the rod 24 will pivot the arm 28 about the pivot connection 30 between the arm 28 and boom 12. A suitable hydraulic cylinder 34 is carried by the arm 28 and is preferably supplied with hydraulic fluid from the usual fluid source (not shown) of the vehicle 10 through the auxiliary conduit or line 36. A reciprocal rod 38 extends axially from the cylinder 34 and the outer extremity of the rod 38 is pivotally secured at 40 to a second arm member 42. The second arm member 42 is preferably sectional and is suitably pivotally secured at 44 to the outer extremity of the first arm 28, and it will be apparent that reciprocation of the rod member 38 will pivot the second arm 42 about the pivot connection 44 for a purpose as will be hereinafter set forth in detail.

The second arm 42 is preferably of a hollow construction and may be of a substantially tubular configuration, but not limited thereto. As hereinbefore set forth, the arm 42 is sectional and comprises an upper connection portion 46 and a lower or outer tubular member 48. The member 48 is rotatably secured to the connection portion 46 by a suitable bearing collar 50 in any well known manner whereby the tube 48 may be rotated independently from the connection member 46. Any suitable type gearing means, or the like, may be provided for rotation of the tube 48, and as depicted herein, the tube 48 is provided with a ring gear mechanism 52 rigidly secured thereto for cooperation with an internal jacking gear 54, the extreme end portion of which is shown in FIGURE 2. The jacking gear 54 may be manually, electrically or hydraulically operated, or the like, as desired. The embodiment shown herein comprises a mechanical or manual operating mechanism wherein the jacking gear 54 is connected with a manual wheel member 56 through a suitable linkage mechanism 58. As clearly shown in FIGURE 2, the linkage mechanism 58 is disposed within the hollow arm 28 and connection member 46, thus providing a casing and protection for the operating mechanism.

The jacking gear 54 and ring gear 52 may be of any suitable type, and preferably function in the manner of such gear arrangements as frequently utilized in traction equalizers in cooperation with vehicle rear wheel axles. Rotation of the jacking gear 54 in one direction by manipulation of the wheel 56 causes the ring gear 52 to rotate in a complementary direction for transmitting rotation to the tube 48. Conversely, rotation of the jacking gear 54 in an opposite direction causes the ring gear 52 to rotate in an opposite direction for reversing the direction of rotation of the tube 48. Of course, when the jacking gear 54 is stationary, the gear 52 does not rotate, and the tube 48 is securely held against rotation.

A hydraulic motor 59 is rigidly secured to the tube 48 in any suitable manner, such as by welding or the like, and is connected with the usual fluid source (not shown) of the vehicle 10 by the

conduits

68 and 62. It is to be noted that the motor 59 may be of any suitable type, and is not limited to a hydraulic motor. A pair of oppositely disposed drive sheaves or pulleys 64 and 66 are driven by the motor shaft 67, and are connected with a pair of oppositely disposed

pulleys

68 and 70 by a pair of

drive belts

72 and 74. The

pulleys

68 and 70 are carried by a transverse shaft 76 which extends through the tube member 48 and is journalled therein in any suitable manner. A drive sprocket member 78 is substantially centrally disposed between the

pulleys

68 and 70 and is suitably keyed or otherwise secured to the shaft 76 for rotation simultaneously therewith. The sprocket 78 extends through cut away portions or

slots

79 and 81 provided in the sides of the tube 48, as clearly shown in FIGURE 3. For the sake of simplicity, FIGURE 3 shows one.driving pulley 66 and one driven pulley 70 which may be entirely adequate for the purpose of rotating the sprocket 78 from the motor 59. The

pulleys

68 and 70 are rotated by the

belts

72 and 74 and drive pulleys 64 and 66, as is well known, and the rotation of the

pulleys

68 and 70 is transmitted to the sprocket 78 through the shaft 76. It will be apparent that a suitable transmission drive may be provided between the motor 59 and the

pulleys

68 and 78 in lieu of the belt drive, if desired. Furthermore, it may be desirable to provide only one pulley 70 (as shown in FIGURE 3) instead of the two

pulleys

68 and 78 to provide the driving power for the sprocket 78, or it may be desirable to provide more than two pulleys.

An idler sprocket is journalled between a pair of spaced bracket members 82, only one of which is shown in FIGURE 2, and the brackets 82 are secured to the outer periphery of the tube 48 in any suitable manner whereby the idler sprocket 80 is spaced from the drive sprocket and in c-o-planar alignment therewith. A third sprocket 84 is journalled at the outer extremity 85 of the tube 48 in alignment with the

sprockets

78 and 88 for receiving a continuous digging chain 86 which extends around the outer circumference of the three

sprockets

78, 8t and 84, as is well known. The outer extremity 85 of the tube 48 may be slotted or bifurcated (not shown), or otherwise open whereby the sprocket 84 may be journalled therein, as clearly shown in FIGURE 2. The digging chain 86 may be of any suitable type and is preferably provided with a plurality of spaced digger blades 88 for scooping or digging away the earth 80 upon movement of the chain 86 around the sprocket 84. Rotation of the drive sprocket 78 by actuation of the motor 58 moves the digging chain 86 around the sprockets 78, 8t) and 84, as is well known. It is preferable that the tube 48 be of a slightly tapered configuration whereby the outer extremity 85 thereof is of a diameter or Width complementary to the blades 88 for facilitating the digging operation. The idler sprocket 88 functions to maintain the chain 86 substantially taut during the digging operation, and the sprocket 84 reverses the direction of the chain 86 and provides the rigidity and downward force on the chain 86 for the digging action of the blades 88 moving therearound.

The distance between the drive sprocket 78 and the sprocket 84 may be selected in accordance with the desired digging results of the apparatus 26. It is to be understood that the tube 48 may be of a telescopic construction (not shown) wherein the distance between the

sprockets

78 and 84 may be adjusted as desired, and a suitable tightening screw 92, cooperating with a slot 94 provided in the tube 48, may be utilized for securely locking the telescopic tube 48 in the desired position for proper spacing between the

sprockets

78 and 84.

FIGURES 4, 5 and 6 show a digging attachment including a right hand ground contacting portion 148 (which can be referred to as the lower or outer member for purpose of comparison with the description of FIG- URES l to 3, inclusive); the outer member 148 is rotatably secured to a left hand member 146 (which for the sake of consistency with FIGURES 1 to 3, inclusive, can be referred to as an inner or upper member). The upper U) member 146 can be secured to the arm 28 (or other suitable and equivalent member) by making a pivotal connection between member 146 and arm 28 at 44, for example, and by connecting the outer end of the rod 38 to the member 146 at 40, for example.

The inner member 146 includes a main cross member 147 of substantial size and strength. At the ends of the cross member 147 are rearwardly extending tongues 151) and 152 having suitable holes therein to provide the pivotal connections 44 referred to above. Intermediate the two tongues 151i and 152 are two additional rearwardly and upwardly extending

tongues

154 and 156 having suitable holes therein to provide the pivotal connections 40 referred to above.

A cylindrical bearing member 158, having a circular end flange 1611 at its right hand end, is suitably secured to the right hand face of the cross member 147 by means of the bolts 162 shown in FIGURES and 6.

The outer or lower member 148 of the digging attachment includes a pair of spaced horizontally extending

plates

164 and 166 which together constitute a yoke means as will hereinafter appear. A cross plate 168 is secured at its ends to the

members

164 and 166, slightly to the right of the ends thereof. A solid circular plate 170 is received between the ends of the

members

164 and 166 is firmly secured to the cross plate 168 by means of the bolts 172 (or by welding, if desired). A bearing ring 174, having an inner diameter substantially equal to the outer diameter of the flange 168, is arranged in abutting relation with the plate 178 and is super-imposed over the flange 160 as shown in FIGURE 6. A circular retaining ring 176, having an inner diameter substantially equal to the outer diameter of the main cylindrical portion of the cylindrical bearing member 158, is arranged in abutting relation with the ring 174 and is received over the main cylindrical portion of the cylindrical bearing member 158 as shown in FIGURE 6. The retaining ring 176 may be split as desired for the purpose of simplifying the assembly of parts to effect the condition shown in FIGURE 6.

A ring gear 178, having an inner diameter substantially equal to the outer diameter of the main cylindrical portion of the cylindrical bearing member 158, is arranged in abutting relation with the retaining ring 176 and is received on the main cylindrical portion of the cylindrical bearing member 158 as shown in FIGURE 6. The ring gear may also be split into two semi'circular segments, for example, to facilitate assembly as mentioned above. A plurality of bolts 186 (only two of which are shown in FIGURE 6 for the sake of simplicity) pass through suitable holes in the

members

170, 174 and 176 and threadedly engage at their left hand ends suitable threaded holes in the ring gear 178 so as to hold together, as a sub stantially integral body, the solid plate 170, the bearing ring 174, the retaining ring 1'76 and the ring gear 178.

A spur gear or pinion 182 disposed in meshing relation with the ring gear 178 is keyed to the end of a shaft 184 suitably mounted for rotation in a journal 186. The journal 186 is suitably secured, for example by welding, to the cross member 147 and the tongue 152. The left hand end of the shaft 184 may be connected to any suitable means to provide rotation for this shaft and the pinion 182. For example, the shaft 184 can be connected to a suitable flexible transmission cable (not shown) leading to a suitable mechanism (not shown) mounted on the tractor which will permit the operator to turn the outer member 148 with respect to the inner member 146 to any rotary position desired. Alternatively, the shaft 184 may connect with the output shaft of a suitable adjacent hydraulic motor (not shown) whose controls would also be within reach of the operator for the same purpose. At any event, it should be apparent that rotation of the pinion 182 will cause the ring gear 178 to rotate on the main cylindrical portion of the cylindrical bearing memher 158, thereby imparting rotary motion to the outer member 148. Proper lubrication of those parts which rotate relative to one another can be effected by the conventional employment of suitable grease fittings, etc. (not shown).

The rotary member 148 has mounted thereon a suitable fiat plate 188 to which the hydraulic motor 59 is fastened in any convenient manner. The output shaft 67 of the motor 59 drives the pulley 66 in the same manner as previously described and the belt 74 couples the output of the pulley 66 with the pulley 70 so as to drive the sprocket 78 in the same manner as previously described. The right hand ends of the

horizontal plates

164 and 166 are suitably bent (through double right angles) as shown in FIGURE 4 so as to be in relatively closely spaced relation, although at the same time, providing sufficient clearance on all sides for the sprocket 78 and the chain 86 which is driven thereby. It should be further understood that sufficient clearance is provided between the

members

164 and 166 and the cross plate 188 to accommodate for the passage of the teeth 88 which may not necessarily be of the same size and shape as shown in the present drawings.

One end of a suitable arm or boom 1% is secured between the right hand ends of the

members

164 and 166 by welding or bolts or any other suitable fastening means. At the extreme right hand end of the boom 191) (which is broken for the sake of convenience in illustration in FIG- URES 4 and 5), there is mounted the sprocket 84 in a slot 192. The idler sprocket is journalled between a pair of spaced bracket members 82 which are secured to the boom 1% as shown in FIGURE 4. The three

sprockets

78, 86 and 84 are all in co-planar alignment to provide for proper movement of the chain 86 therearound. The idler sprocket 80 may be adjustable outwardly or inwardly (in a manner not shown) to provide proper tension for the chain 86 in a substantially conventional manner.

OPERATION When it is desired to dig a trench through an extended distance, the digging apparatus 26 may be secured to the arm 28 on the boom 12 of the backhoe vehicle 10 in lieu of any other attachments (not shown) which may be provided thereon. In addition, the conduit 36 of the hydraulic cylinder 34 and the conduits 6t) and 62 of the hydraulic motor 59 may be suitably connected with the hydraulic fluid source usually provided with the vehicle 10 for actuation or operation by the operator of the ve- =hicle as is well. known. Of course, a separate fluid source (not shown) may be provided for the apparatus 26, if desired.

The boom 12 may be raised and lowered and rotated in a horizontal plane by the vehicle operator in the usual manner. Reciprocation of the rod 24 of the hydraulic cylinder 22 will pivot the arm 28 with respect to the boom 12. Similarly, reciprocation of the rod 38 of the cylinder 34- will pivot the arm 42 with respect to the arm 28. Thus, the disposition of the digging chain 86 may be adjusted to substantially any desired location with respect to the vehicle 10 by the control of the vehicle operator. In the fully extended position of the apparatus 26 and the boom 12, the digging chain 86 may be positioned at a substantial distance from the vehicle 19, and through the manipulation of the hydraulic cylinders 22 and 34 in the well known manner, the digging operation may be performed continuously from the fully extended position of the apparatus 26 to a fully contracted position therefor.

For example, the boom 12 may be lowered or moved to the outermost reaching position therefor. The rod 24 may be receded or withdrawn into the cylinder 22 for pivoting the arm 28 in a clockwise direction about the pivot connection 30, as viewed in FIGURE 1. This tends to straighten the arm 28 out-wardly with respect to the boom 12. The rod 38 may then be moved into the cylinder 34 for pivoting the arm 42 in a clockwise direction about the pivot connection 44, as viewed in. FIGURE 1.

Thus, the digging attachment 26 will be positioned in a substantially straight line with the bottom 12, and will extend outwardly from the vehicle in a substantially perpendicular disposition with respect thereto. As the digging operation progresses, the cylinders 34 and 22 may be actuated in the usual manner by the operator of the vehicle for rotating the

arms

28 and 42 in counterclockwise directions about the

respective pivot connections

30 and 44, with a simultaneous raising of the boom 12, thus moving the arm 42 and digging chain carried thereby in a direction toward the vehicle. The digging operation, as will be hereinafter set forth, may be progressed continuously during the movement of the

arms

28 and 42 and boom 12, thus providing a continuous trench from a position spaced at a considerable distance from the vehicle 10 to a position very close to, or even under the vehicle. Of course, when the trench is being dug off-set or at the side and parallel to the vehicle, the boom 12 may be rotated in the horizontal plane by the upright member 14, and the trench may be continued to a position forwardly of the Vehicle.

In order to provide power for the digging operation, the hydraulic motor 5 is energized or activated in the usual manner by the operator of the vehicle whereby the pulleys 64 and 66 drive the

pulleys

68 and 70 through the

belts

72 and 74, respectively, for rotating the drive sprocket 78. The rotation of the sprocket 78 moves the endless digging chain continuously around the

sprockets

78, 80 and 84, as is well known, and the digging blades 88 function to remove the earth for digging the trench. The chain 86 may be continuously operated as desired for digging the trench in an uninterrupted operation. It will be apparent that the

slots

79 and 81 in the tube 48 are sufficiently Wide to provide clearance for the digging blades 88 as the chain 86 passes over the drive sprocket 78.

When the trench is being dug off-set or at the side of the vehicle 10, it may be desirable to orientate the digging chain with respect to the vehicle in order to provide a continuous trench. Thus, the tube 48 may be rotated for orientating the digging chain properly to provide the desired digging results. Manual operation of the wheel 56, or rotation thereof by the operator of the vehicle for manipulating the mechanical linkage mechanism 58 causes the jacking gear 54 to rotate the ring gear 52 for transmitting rotation to the tube 48. The tube 48 may be rotated about the longitudinal axis thereof throughout any desired angular change for the plane of the digging chain 86, thus permitting the digging of a long and continuous trench which is off-set from the vehicle 10, such as when digging a trench adjacent to a highway or the like.

If it is desired to utilize the digging apparatus 26 with a farm tractor or the like (not shown), it may be preferable to omit the first arm member 28 and use only the second arm 42 and cooperating members therewith. In this instance, the pivot connection 40 may be connected directly with the hydraulic cylinder of the tractor and the pivot connection 44 may be connected directly to the boom of the tractor. Of course, it may be preferred to secure the arm 42 to a suitable simple two-wheeled cart, or the like (not shown), which is connected to the farm tractor by a Winch line, or spring arrangement (not shown) for relatively slow and steady pulling or towing of the trench digging apparatus. It will be apparent that this arrangement will substantially eliminate transmitting of uneven or jerking movements of the tractor to the trenching device. The operation of the digging chain 86 and orientation thereof will be as hereinbefore set forth.

Although the description of the operation of the present invention has been set forth above in particular regard to FIGURES 1 to 3, inclusive, the operation of the embodiment shown in FIGURES 4 to 6, inclusive, is sufficiently similar to the foregoing so as to obviate the necessity of &

reiterating the same principles of operation with regard to the latter embodiment.

From the foregoing, it will be apparent that the present invention provides a novel digging attachment for vehicles which is particularly designed for simplicity of construction and operation. The novel digging attachment provides for the digging of a long and continuous trench with great facility. The digging chain may be operated continuously and the digging operation may progress through a substantially great distance independently of the movement of the vehicle, thus providing for the digging of trenches through adverse terrain. In addition, a trench may be dug off-set or at the side of the vehicle in a continuous and uninterrupted manner regardless of obstacles which the vehicle may encounter. The digging ap aratus may be utilized with substantially any tractor type vehicle, such as a farm tractor, backhoe, or the like, with equal efficiency of results.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

What is claimed is:

1. A digging attachment for a vehicle of the type having a hydraulic pressure system and a piston-cylinder device thereon operated by said system, said digging attachment comprising an inner member, means for pivotally attaching said inner member to said vehicle, means for connecting said inner member to said piston-cylinder device, whereby, when said piston-cylinder device is actuated, said inner member pivots relative to said vehicle about said pivotally attaching means, a longitudinally extending outer member rotatably mounted at one end on said inner member for rotation of said outer member about its longitudinal axis, means interacting between said outer member and said inner member for rotating said outer member relative to said inner member, a first sprocket journalled for rotation in the other end of said outer member, a second sprocket disposed in spaced relation with respect to said first sprocket and journalled in said outer member, said first and second sprockets being rotatable in a substantially co-planar disposition, a continuous digging chain having spaced digger blades thereon extending around said sprockets and being driven thereby, a hydraulic motor mounted on said outer member and having a rotary output connected in driving relation with said second sprocket, and means connecting said hydraulic motor with said hydraulic system for driving said motor.

2. A digging attachment for a vehicle of the type having a hydraulic pressure system and a piston-cylinder device thereon operated by said system, said digging attachment comprising an inner member, means for pivotally attaching said inner member to said vehicle, means for connecting said inner member to said piston-cylinder device, whereby, when said piston-cylinder device is actuated, said inner member pivots relative to said vehicle about said pivotally attaching means, a longitudinally extending outer member rotatably mounted at one end on said inner member for rotation of said outer member about its longitudinal axis, a first gear mounted on said outer member adjacent said inner member and substantially co-axial with the longitudinal axis of said outer member, a second gear rotatably mounted on said inner member and engaging said first gear in driving relation, means for rotating said second gear to rotate said outer member relative to said inner member, a first sprocket journalled for rotation in the other end of said outer member, a second sprocket disposed in spaced relation with respect to said first sprocket and journalled in said outer member, said first and second sprockets being rotatable in a substantially co planar disposition, a continuous digging chain having spaced digger blades thereon extending around said sprockets and being driven thereby, a hydraulic motor mounted on said outer member and having a rotary output connected in driving relation with said second sprocket, and means connecting said hydraulic motor with said hydraulic system for driving said motor.

References Cited by the Examiner UNITED STATES PATENTS Mather 287-91 X Farr.

Osgood 299-72 Stein 299-72 Brant 37-86 Davis 143-4334 X Barber 37-86 Hyster 37-191 Cramer 37-86 Kashergen 214-138 ABRAHAM G. STONE, Primary Examiner.

1o BENJAMIN MERSH, WILLIAM A. SMITH III,

Examiners.

W. B. STONE, Assistant Examiner.