US3871538A

US3871538A - Rotary extendable dipperstick

Info

Publication number: US3871538A
Application number: US211879A
Authority: US
Inventors: Laurence B Miller; James D Crook
Original assignee: Individual
Current assignee: MILLER LAURENCE B
Priority date: 1971-12-27
Filing date: 1971-12-27
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18

Abstract

An earth excavating device commonly known as a backhoe, said backhoe having an extendable dipper-stick thereon which is also adapted to rotate in a substantial manner about its longitudinal axis.

Description

United States Patent Miller et a1.

ROTARY EXTENDABLE DIPPERSTICK Inventors: Laurence B. Miller; James D.

Crook, both of 354 Tennessee, Redlands, Calif.

Filed: Dec. 27, 1971 Appl. No.: 211,879

U.S. C1. 214/141, 214/1465 Int. Cl E021 3/28 Field of Search 214/141, 146.5, 138 R,

References Cited UNITED STATES PATENTS 6/1964 Przybylski 214/141 Mar. 18, 1975 3,232,451 2/1966 Andren 214/1 BB 3,445,015 5/1909 Sampo .7 214/138 R 3,624,785 12/1970 Wilson 214/141 3,700,126 10/1972 Beaton 214/141 Primary E.\'aminer-Albert J. Makay Assistant Examiner-George F. Abraham Attorney, Agent, or Firm-Bernard M. Smukler [57] ABSTRACT An earth excavating device commonly known as a backhoe, said backhoe having an extendable dipperstick thereon which is also adapted to rotate in a substantial manner about its longitudinal axis.

10 Claims, 5 Drawing Figures F'MENTED 3.871.538

' sum 2 0F 2 Fig. 4.

ROTARY EXTENDABLE DIPPERSTICK This invention relates in general to earth excavating devices and more particularly to hydraulically maneuverable and operable backhoe equipment having an extendable and rotable dipper-stick thereon, for use in conjunction with conventional mechanized transport means. In operation, the said equipment, among other things, excavates or scoops up in a conventional .type bucket various earth materials, removes same from the trench created thereby, and discharges or dumps said materials from said bucket into a selected area or container.

In the rapidly expanding land development and construction industries of today, it is often required to quickly and easily excavate various materials from the earth or form tunnels in the earth so that utility pipes or other such improvements may be placed therein. Further, there are many times when it is desired or considered better engineering practice to form a tunnel or trench in the earth having sides or walls which are not perpendicular to the surface plane of the earth. Of course, various excavating devices, including both manual skills and various attachments to vehicular or transport means, have been employed in the past for digging, lifting, swinging and dumping work. However, utilization of manual devices has resulted in a poor quality of trenching, in addition to being a slow and tedious work. Apparently, this follows from the general physical limitations inherent in a human being whenever required to directly perform heavy construction work.

When excavating devices have been attached to various vehicular or transport means, including conventional construction tractors, a good quality of trenching results with a considerable saving of time and human energy. The devices include a maneuverable boom member which is ordinarily attached to the transport means and carries a dipper-stick (digging device) that supports at one end an open-mouth backhoe digging bucket. However, several disadvantages are apparent from such use which limit greater utilization of the equipment as well as its depth capabilities. A short time prior to the present invention, the length of the combined dipper-stick and bucket was restricted so as not to exceed the length of the boom member. Otherwise, a portion of the combination of dipper-stick and bucket would of necessity trail upon the ground causing severe damage to the equipment. If greater digging depth was required, the length of the dipper-stick could be increased provided the length of the boom member was correspondingly increased. As is obvious, this physical limitation resulted in extremely cumbersome equipment. Several attempts have now been made to increase the length of the dipper-stick without increasing the standard length of the boom member, but such efforts have resulted in an extendable dipper-stick member which can excavate in a vertical plane only. Further, several attempts have been made to cause the dipper-stick to excavate at a non-perpendicular angle relative to the plane of the earth, but shch efforts have re sulted in a device which is not extendable at all and which has less than adequate torque capability thereto so that the attendant digging bucket cannot be filled to its maximum volume. Such prior devices have therefore caused substantial damage to the dipper-stick and boom member without accomplishing the primary purpose of substantially increasing the depth capacity of mechanized backhoe equipment, with the same being adapted to rotate about the longitudinal axis of the dipper-stick so as to excavate materials in either a perpendicular plane or a non-perpendicular plane relative to the surface of the earth.

It is therefore the primary purpose and object of this invention to provide a continuous action hydraulically operated backhoe, for use with conventional vehicular or transport means, which is capable of digging at greater depths than heretofore accomplished while the same is adapted to rotate about the longitudinal axis of its dipper-stick so as to excavate materials in either a perpendicular plane or a non-perpendicular plane relative to the surface of the earth.

A further object of this invention is to provide an extendable and rotable dipper-stick adapted for use with and attached to all conventional backhoe equipment without the necessity of increasing the length of the boom member, without causing any portion of the extendable dipper-stick or bucket to trail upon the ground and without causing any structural defect in the device.

Another object of this invention is to provide a backhoe adapted for attachment to conventional vehicular or transport means which can be easily moved into the desired position and speedily excavate either vertically or at various angles relative to the plane of the earths surface.

A further object of this invention is to provide a backhoe adapted for attachment to conventional vehicular or transport means which can be easily moved into the desired position and speedily excavate more feet of trench than heretofore known and efficiently swing and dump earth material from the trench or excavation created thereby.

An additional object of this invention is to provide backhoe equipment which can be easily placed within or withdrawn from narrowly dimensioned trenches or excavations.

Other and additional objectives and advantages of this present invention are to provide a durable extendable and rotable dipper-stick of maximum simplicity and efficiency combined with safety, economy of manufacture and ease of operation; to provide such a device which is adapted to excavate a tunnel or trench with the angles of the walls thereof relative to the plane of the earth being varied according to the desires of the operator of such equipment; and such objectives, advantages and capabilities will be readily apparent and better understood by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a perspective view of a backhoe device in cluding the present invention, together with an ordinary backhoe bucket, secured to conventional tractor means (not fully shown);

FIG. 2 is a perspective view of the dipper-stick means of the present invention;

FIG. 3 is a horizontal cross-sectional view taken along line 3--3 of FIG. 2 of the dipper-stick means;

FIG. 4 is a partial cross-sectional view of another portion of the said dipper-stick means of the invention, which view is taken along line 4-4 of FIG. 2; and

FIG. 5 is a horizontal cross-sectional view taken along line 55 of FIG. 2 of the drawing.

Referring to the drawing in detail, a maneuverable steel boom member 11 is shown in FIG. 1 pivotly connected at one end thereof to mechanized transport means 13, which usually is a tracked or a rubber tire vehicle of a type conventionally used in the construction industry. Maneuverable and extendable dipper-stick means are pivotly connected at one of its ends to the other end of boom member 11 by means of a conventional shaft 15, as more fully described hereinbelow. An excavating tool such as a conventional steel backhoe bucket 29 is pivotly connected by linkage means 29c to the other end of the said dipper-stick means 10. The said shaft connecting boom 11 to dipper-stick means 10 permits said dipper-stick means 10 to rotate in a plane substantially perpendicular to the surface of the earth. Further, the pivot connection (not shown) between boom member 11 and the transport means 13 permits movement in both horizontal and vertical planes relative to the surface of the earth.

As may be seen by viewing FIG. 2 of the drawing, the said dipper-stick means 10 is fixedly attached to a support frame shown as 16, which frame 16 consists of two irregularly shaped metal side plates, 16b and 160, weldably affixed to the undersurface of a horizonal base plate 16a. Said support frame 16, is adapted to support thereon a hydraulic rotory motor 17 and various bearing members (hereinafter described) adapted to hold and retain the said dipper-stick means 10 in position I relative to said support frame 16. Of course, said horizontal base plate 16a may consist of several of such plates stacked in a vertical manner so as to provide additional support for the dipper-stick means 10 or for the mounting brackets (hereinafter described) depending on the particular model and type of backhoe machine. In any event, a plurality of hole means 14 are provided on said side plates, 16b and 16c, and are adapted to retain therein a plurality of pin means or

shafts

14a or 15 for purposes hereinafter discussed.

As is now evident, the shaft 15 connects the support frame 16 to the bottom member 11, and said dipperstick means 10 are supported on said frame 16. Further, said dipper-stick means 10 are maneuverable in a vertical plane relative to the surface of the earth by means of a hydraulically operated cylinder and its associated dipper-stick actuating rod 12 which are mounted and pivotly connected at one end to boom member 11 and pivotly attached at its other end to shaft 14a fixedly engaged between said

side plates

16b and 16c. The said boom member 11 is maneuverable in its vertical plane relative to the surface of the earth by means of a hydraulically operated cylinder (not shown) and its associated boom actuating rod (also not shown).

The said dipper-stick means 10 comprise a hollow steel shaft 20 and a hollow steel extension member 23 adapted to partially and slideably fit without said shaft 20. The shapes of said shaft 20 and extension member 23 are not particularly important, except that they should be similar in design so as to insure a tight fit between the same particularly when they are in slideable engagement with each other. Two relatively thin metal bracket members 27 are weldably attached to opposite vertical faces of said extension member 23 as shown in FIG. 2 of the drawing, and are disposed to accommodate therebetween pin means 27a for purposes hereinafter discussed.

A hydraulically operated cylinder 28 and its associated bucket actuating rod 28a are pivotly connected at one end by said pin means 27a to said bracket members 27, and pivotly attached at their other end to said bucket 29 by means of connecting the end of said actuating rod 28a to horizontal pin 29a which in turn is connected to links 29b. As may seen in FIG. 1 of the drawing, two of said links 29b are fixedly attached to said bucket 29. Further, the said extension member 23 is likewise attached to said bucket 29 by means of said linkage 290. In any event, a hydraulically operated cylinder 30 and its associated extension member actuating rod 30a are pivotly connected to one end of the said dipper-stick shaft 20 by means of a pin 31 rigidly supported within the inner vertical sides of the said shaft 20 as shown in FIG. 2 of the drawing. The other end of the said cylinder 30 and rod 30a is supportably attached to a clevis 32, which in turn is fixedly attached to the corresponding vertical inner sides of the said extension member 23 by the associated trunnion supports 32a.

The rotary motor or actuating device 17 is well known to those skilled in the art and is capable of rotating

shaft members

20 and 23, respectively, about their coincident longitudinal axes up to a maximum of approximately in either a clockwise or counterclockwise direction, all as hereinafter disclosed. A cylindrically shaped power shaft member 22 is adapted to cooperate at one end thereof with the said rotary motor or actuator 17, and is axially and fixedly mounted at its other end to a metal plug 21. Said plug 21 is adapted to fit partially, by means of a standard slip fitting operation, within one end of said shaft 20, which shaft 20 in turn is supported at such end thereof by

bearings

18 and 19, respectively. As a result, the end of said shaft 20 adjacent to motor 17 is essentially closed. Further, and as hereinafter discussed, when said motor 17 causes shaft member 22 to rotate about its longitudinal axis, thus causing the said plug 21 to likewise rotate, the force thereof will cause a portion of said

bearings

18 and 19 and the shaft 20 to similarly rotate about their longitudinal axes.

Said

bearings

18 and 19 are mounted on said support plate 16a, and they are set so that their longitudinal axes are coincident with each other and form a line parallel to the plane of said plate 16a. Said

bearings

18 and 19 consist of substantially rigid inner races, 35 and 36, respectively, and substantially rigid outer races, 33 and 34 respectively, which are adapted to fit together by means of appropriate pressure being applied thereto. Said inner races, 35 and 36,, are adapted to revolve within outer races, 33 and 34, respectively. As may be seen in FIG. 4 and FIG. 5 of the drawing, said

bearings

18 and 19 are similar in size and construction and are adapted to eliminate longitudinal or torque movement of said shaft 20 interposed between said

bearings

18 and 19. Thus, the said inner races, 35 and 36, are hollowed at their respective axes, with the shape thereof conforming to that of the said dipper-stick shaft 20. From a review of FIG. 5 of the drawing, it is noted that the end of said shaft 20 is inserted by appropriate pressure means into the hollow portion of said inner race 35 of bearing 18, and the plug 21 is snugly inserted into the said end of shaft 20. In any event, between said outer race and inner race of each of said

bearings

18 and 19, are interposed nylon or other type of bearing material 37 which is adapted to substantially reduce friction between said inner races, 35 and 36, and outer races, 33 and 34, respectively, when same revolve relative to each other. Further, and as may be appreciated, the design of said outer races, 33 and 34, and the placement therein of said inner races, 35 and 36, respectively, prevents longitudinal displacement of said shaft 20. In other words, regardless of the load on, or position of the dipper-stick means 10, said shaft remains stationary along its longitudinal axis. Of course, the design of said outer races, 33 and 34, and said inner races, 35 and 36, may vary without departing from the spirit or scope of the present invention. For example, the circumferential surface between outer and inner races, 33 and 35, may slope downwardly towards the said closed end of said shaft 20 and the circumferential surface between outer and inner races, 34 and 36, may slope upwardly towards the said closed end of said shaft 20 so as to similarly prevent longitudinal movement of said shaft 20 relative to plate 16a.

At one end of the said extension member 23, where it is adapted to receive the non-closed end of said shaft 20, are four flat wear or

bearing plates

24a, 24b, 24c and 24d, rigidly attached to the inner sides of said ex tension member 23 by screw means, and said

plates

24a, 24b, 24c, and 24d, are in slideable engagement with the outer surfaces of the said shaft 20. At the nonclosed end of said shaft 20 are four'flat wear or bearing plates a, 25b, 25c (not shown) and 25d (not shown), rigidly attached to the outer surfaces of the said shaft 20 by screw means, and said

plates

25a, 25b, 25c and 25d, are in slideable engagement with the inner sides of said extension member 23.

As a result, the combination of said shaft 20 and extension member 23 forms a telescopable arm capable of being extended and retracted along their longitudinal axes. Of course, only the extension member 23 extends or retracts along its axis. Further, if the said inner races, and 36, are circular in shape so as to permit rotable motion within the outer races, 33 and 34 respectively, as aforesaid, then upon actuation of the power shaft 22 causing rotation in the plug 21, the said combination will likewise rotate about its longitudinal axis. As may also be appreciated, the combination of said

wear plates

24a, 24b, 24c and 24d with the said

wear plates

25a, 25b, 25c and 25d prevents disengagement between said extension member 23 and said hollow shaft 20. In other words, when the said extension member 23 is fully extended relative to said shaft 20, contact between the edges of said

plates

24a, 24b, 24c and 24d and the edges of said

plates

25a, 25b, 25c and 25d keeps said member 23 and shaft 20 in slideable engagement. Finally, as seen in FIG. 2 of the drawing, a reinforcing collar 26 is mounted about bearing

plates

24a, 24b, 24c, and 24d outside of said member 23. The construction of the dipper-stick means 10 as hereinabove described permits the bucket 29 to articulate in a normal fashion and also permits the rotation of said bucket 29 about the longitudinal axis of said dipperstick means 10 without using mechanisms other than those found to be an integral part of said dipper-stick means 10.

Once the backhoe equipment, including the present invention, is maneuvered into working position by the operator of the mechanized transport means 13, the necessary hydraulic power to operate the various components and elements of the said backhoe as aforesaid is provided by oil pressure from an external source through various input and output oil lines, some of which 38 are completely or partially shown in the drawmg.

In operation, the transport means 13 is moved to and positioned over the region to be excavated or tunneled, and the operator thereof then approximately sets the boom member 11 over the designated area. If the required depth is within the capability of the dipper-stick means 10 alone, without any extension of same, the operator simply excavates or tunnels the earth by means of manipulating the boom member 11 by its actuating hydraulic cylinder and associated rod (not shown), the dipper-stick means 10 by its hydraulic cylinder and associated rod 12 and the bucket 29 by its hydraulic cylinder and associated rod, 28 and 28a respectively. If a greater depth to the excavation or tunnel is necessary, or if the same must be extended in length without moving the transport means 13 to the new location, the operator would utilize the extension member 23 as hereinabove described. Thus, the dipper-stick means 10, together with the extension member 23, provide a source of substantial additional length for ordinary backhoe equipment, and they are capable of replacing existing dipper-sticks on such equipment. Further, if the excavation or tunnel must have walls thereto which are not to the surface of the earth, the operator would utilize the rotary motor 17 of the invention so as to cause the said dipper-stick means 10 to rotate about its axis until a proper degree of angle is obtained. As indicated above, the bucket 29 is likewise rotated so that its angle of scoop" will conform with the angle of rotation of said dipper-stick means 10. Its use results in a substantial increase of the effective excavating depth of such equipment and in the ability to trench out from a tunnel by means of excavating the sides thereof. Of course, the bucket 29 is operable by the hydraulic cylinder and actuating rod regardless of whether or not the extension member 23 or rotary motor 17 is being utilized.

Although the present invention has been described and illustrated with a certain degree of particularity, it is to be expressly understood that the present disclosure was made by way of example only and that many variations are possible. In any event, the said present invention is not intended to be restricted to any particular construction or arrangement, or to any specific embodiment disclosed herein, or any specific method of operation or use, since the same may be modified in various particulars or relations without departing from the spirit or scope of the claimed invention hereinabove shown and described of which the embodiments are intended only for illustration and for disclosure of at least one operative embodiment, and not to show all of the various forms and modifications in which the invention might be embodied.

We claim:

1. An excavating device adapted to be attached to transport means, said device comprising: a boom member attached at one of its ends to transport means; a support frame connected to the other end of said boom member; motor means attached to said support frame; a non-extendable shaft connected at one of its ends to said motor means; said motor means being adapted to revolve said shaft about its longitudinal axis; a hollow member having one of its ends adapted to slideably and telescopically receive therein the other end of said shaft; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attached at one end to said shaft and at the other end to said hollow member so as to be able to extend or retract the effective combined length of said hollow member and shaft by causing movement of said member along its longitudinal axis relative to said shaft; an excavating tool such as a backhoe bucket connected to the other end of said hollow member; said hollow member and shaft being adapted to cooperate with each other so that when said shaft revolves about its axis, as aforesaid, the said hollow member and tool will likewise revolve about the longitudinal axis of said hollow member; and means carried by said hollow member and adapted to actuate said tool.

2. An excavating device as described in claim 1 above, whereby means are provided on the receiving end of said hollow member and the said other end of said shaft, which means cooperate with each other so as to prevent disengagement of said shaft and member.

3. An excavating device adapted to be attached to transport means, said device comprising: a boom member attached at one of its ends to transport means; a support frame pivotly connected to the other end of said boom member; motor means attached to said support frame; a non-extendable shaft connected at one of its ends to said motor means; said motor means being adapted to revolve said shaft about its longitudinal axis upon actuation thereof; bearing members provided on said support frame and adapted to revolveably support said shaft; a hollow member having one of its ends adapted to slideably and telescopically receive therein the other end of said shaft; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attached at one end to said shaft and at the other end to said hollow member so as to be able to extend or reduce the effective combined length of said hollow member and shaft by causing movement of said member along its longitudinal axis relative to said shaft; an excavating tool such as a backhoe bucket connected to the other end of said hollow member; said hollow member and shaft being adapted to cooperate with each other so that when said shaftrevolves about its axis, as aforesaid, the said hollow member and tool will likewise revolve about the longitudinal axis of said hollow member; and means carried by said hollow member and adapted to actuate said tool.

4. An excavating device as described in claim 3 above, whereby said bearing members comprise: first and second outer races attached to said support frame; each of said outer races having centrally disposed hollow portions; first and second inner races adapted to be revolvably supported within said hollow portions by said first and second outer races, respectively; rectangularly shaped and centrally disposed hollow portions provided within said inner races and adapted to accommodate therein said nonextendable shaft; and the adjacent surfaces of said outer races and inner races sloping in such a manner that movement of the said shaft is prevented along its longitudinal axis.

5. An excavating device adapted to be attached to transport means, said device comprising: a boom member pivotally attached one end thereof to said transport means; a support frame pivotally connected to the other end of said boom member; motor means rigidly attached to, and supported by, said support frame; a hollow non-extendable shaft connected at one of its ends to said motor means; said motor means being adapted to revolve said shaft about its longitudinal axis upon actuation thereof; bearing members rigidly provided on said support frame and adapted to revolveably support said shaft; a hollow extension member having one of its ends adapted to telescopically and slideably receive therein the other end of said shaft so that the longitudinal axes of said shaft and extension member are essentially coincident; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attached at one end to said shaft and at the other end to said hollow member so as to be able to extend or reduce the effective combined length of said extension member and shaft by causing movement of said extension member along its longitudinal axis relative to the said shaft; means provided on the receiving end of said extension member and the said other end of said shaft, which means cooperate with each other so as to prevent disengagement of said shaft and member; an excavating tool such as a backhoe bucket connected to the other end of said extension member; and means carried by said extension member and adapted to actuate said tool.

6. An excavating device as described in claim 5 above, whereby said bearing members comprise: first and second outer races attached to said support frame; each of said outer races having centrally disposed hollow portions; first and second inner races adapted to be revolvably supported within said hollow portions by said first and second outer races, respectively; rectangularly shaped and centrally disposed hollow portions provided within said inner races and adapted to accommodate therein said non-extendable shaft; and the ad jacent surfaces of said outer races and inner races sloping in such a manner that movement of the said shaft is prevented along its longitudinal axis.

7. An excavating device adapted to be attached to transport means, said device comprising: a boom member pivotally attached at one end thereof to said transport means; a support frame pivotally connected to the other end of said boom member; motor means rigidly attached to, and supported by, said support frame; a hollow non-extendable shaft; bearing means provided on said support frame and adapted to revolvably support said shaft; means connecting one end of said shaft to said motor means so that upon actuation thereof, said shaft may revolve about its longitudinal axis; a hollow extension member having one of its ends adapted to telescopically and slideably receive therein the other end of said shaft so that said extension member is supported thereby; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attached at one end to said shaft and at the other end to said hollow member so as to be able to extend or reduce the effective combined length of said extension member and shaft by causing movement of said extension member along its longitudinal axis relative to said shaft; an excavating tool such as a backhoe bucket connected to the other end of said extension member; said extension member and shaft being adapted to cooperate with each other so that when said shaft revolves aboutits axis, as aforesaid, the said extension member and tool will likewise revolve about the longitudinal axis of said extension member; and means carried by said extension member and adapted to actuate said tool.

8. An excavating device as described in claim 7 above, whereby means are carried by said boom member and adapted to actuate said support frame.

9. An excavating device as described in claim 7 above, whereby said bearing members comprise: first and second outer races attached to said support frame; each of said outer races having centrally disposed hollow portions; first and second inner races adapted to be revolvably supported within said hollow portions by said first and second outer races, respectively; rectangularly shaped and centrally disposed hollow portions provided within said inner races and adapted to accommodate therein said non-extendable shaft; and the adjacent surfaces of said outer races and inner races sloping in such a manner that movement of the said shaft is prevented along its longitudinal axis.

10. An excavating device as described in claim 8 above, whereby said bearing members comprise: first and second outer races attached to said support frame; each of said outer races having centrally disposed hollow portions; first and second inner races adapted to be revolvably supported within said hollow portions by said first and second outer races, respectively; rectangularly shaped and centrally disposed hollow portions provided within said inner races and adapted to accommodate therein said non-extendable shaft; and the adjacent surfaces of said outer races and inner races sloping in such a manner that movement of the said shaft is prevented along its longitudinal axis.

Claims

3. An excavating device adapted to be attached to transport means, said device comprising: a boom member attached at one of its ends to transport means; a support frame pivotly connected to the other end of said boom member; motor means attached to said support frame; a non-extendable shaft connected at one of its ends to said motor means; said motor means being adapted to revolve said shaft about its longitudinal axis upon actuation thereof; bearing members provided on said support frame and adapted to revolveably support said shaft; a hollow member having one of its ends adapted to slideably and telescopically receive therein the other end of said shaft; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attached at one end to said shaft and at the other end to said hollow member so as to be able to extend or reduce the effective combined length of said hollow member and shaft by causing movement of said member along its longitudinal axis relative to said shaft; an excavating tool such as a backhoe bucket connected to the other end of said hollow member; said hollow member and shaft being adapted to cooperate with each other so that when said shaft revolves about its axis, aS aforesaid, the said hollow member and tool will likewise revolve about the longitudinal axis of said hollow member; and means carried by said hollow member and adapted to actuate said tool.

6. An excavating device as described in claim 5 above, whereby said bearing members comprise: first and second outer races attached to said support frame; each of said outer races having centrally disposed hollow portions; first and second inner races adapted to be revolvably supported within said hollow portions by said first and second outer races, respectively; rectangularly shaped and centrally disposed hollow portions provided within said inner races and adapted to accommodate therein said non-extendable shaft; and the adjacent surfaces of said outer races and inner races sloping in such a manner that movement of the said shaft is prevented along its longitudinal axis.

7. An excavating device adapted to be attached to transport means, said device comprising: a boom member pivotally attached at one end thereof to said transport means; a support frame pivotally connected to the other end of said boom member; motor means rigidly attached to, and supported by, said support frame; a hollow non-extendable shaft; bearing means provided on said support frame and adapted to revolvably support said shaft; means connecting one end of said shaft to said motor means so that upon actuation thereof, said shaft may revolve about its longitudinal axis; a hollow extension member having one of its ends adapted to telescopically and slideably receive therein the other end of said shaft so that said extension member is supported thereby; said hollow member being entirely supported by said shaft; means comprising a piston and cylinder assembly which is attacheD at one end to said shaft and at the other end to said hollow member so as to be able to extend or reduce the effective combined length of said extension member and shaft by causing movement of said extension member along its longitudinal axis relative to said shaft; an excavating tool such as a backhoe bucket connected to the other end of said extension member; said extension member and shaft being adapted to cooperate with each other so that when said shaft revolves about its axis, as aforesaid, the said extension member and tool will likewise revolve about the longitudinal axis of said extension member; and means carried by said extension member and adapted to actuate said tool.