US3858940A

US3858940A - Method of advancing a continuous mining machine and apparatus therefor

Info

Publication number: US3858940A
Application number: US365061A
Authority: US
Inventors: Joseph V Lagowski
Original assignee: WILCOX Manufacturing CO Inc
Current assignee: WILCOX Manufacturing CO Inc
Priority date: 1973-05-30
Filing date: 1973-05-30
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07

Abstract

A continuous miner having improvements therein for enabling the same to be advanced in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof in a cycle which includes positioning the continuous miner adjacent one end of the arcuate face of the coal seam, effecting a pivotal movement of the continuous miner across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement and then effecting a pivotal movement of the continuous miner across the advanced face from said other end to a position adjacent said one end about an axis spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement.

Description

Tlnite ttes atent 1191 lsagowslti 1 .llan.7,1975

[ METHOD OF ADVANCING A CUNTHNUOUS MINING MACHINE AND APPARATUS THEREFOR [75] Inventor: Joseph V. Lagowski, Madscott, W.

[73] Assignee: Wilcox Manufacturing Co. Inc,

Raleigh, W. Va.

[22] Filed: May 30, 1973 [21] Appl. No.: 365,061

Primary Examir1erErnest R. Purser Attorney, Agent, or FirmCushman, Darby & Cushman [57] ABSTRACT A continuous miner having improvements therein for enabling the same to be advanced in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof in a cycle which includes positioning the continuous miner adjacent one end of the arcuate face of the coal seam, effecting a pivotal movement of the continuous miner across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement and then effecting a pivotal movement of the continuous miner across the advanced face from said other end to a position adjacent said one end about an axis spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement.

13 Claims, 13 Drawing Figures PATEHTEDJAN N975 3 858 94 sum 20! s [IOU FIG.2D

METHOD OF ADVANCING A CONTINUOUS MINING MACHINE AND APPARATUS THEREFOR This invention relates to coal mining and more particularly to improvements in the method and apparatus for advancing continuous mining machines in a coal seam.

While the principles of the present invention have applicability to continuous mining machines embodying other types of cutters, the invention has been particularly developed for applicability with continuous mining machines of the dual auger type. Machines of this type are commercially manufactured and sold under the trademark Wilcox MARK 20 by the Wilcox Manufacturing Co. of Beckley, West Virginia. A similar machine, designated the 100L, is manufactured by Jeffrey Manufacturing Company of Columbus, Ohio. The basic construction and mode of operation of these machines is disclosed in Wilcox US. Pat. No. 3,026,098. (See also related U.S. Pat. Nos. 3,282,403; 3,305,268; and 3,306,667.)

Machines of the dual auger type, as the name implies, employ two augers as the means for removing the coal from the seam. The augers are oppositely pitched with respect to each other and are mounted on the frame of the machine in forwardly disposed relation with their axes extending generally horizontally forwardly in horizontally spaced parallel relation. The augers are mounted for power driven rotation in opposite directions and for independent vertical movement, as by a pivotal action about an axis parallel to the axis of rotation. Each auger includes a pair of helical blades having a series of cutting teeth atthe forward end thereof and a series of teeth extending outwardly of the periphery thereof in longitudinally spaced relation therealong.

The means provided for advancing the auger cutters into the coal seam is similar to that provided in the old undercutting machines, namely, a power driven winch or drum on each side of the frame and a length of cable wound up on each drum. Continuous mining during advancement is accomplished by providing a conveyor on the frame which serves to move the coal removed from the seam by the auger cutters to the rear end of the frame where it can then be conveyed out of the mine by an appropriate conveyor system mounted therein.

Dual auger continuous mining machines of the construction noted above have been advanced into the coal seam by sequentially performing two separate operations, the first of which is referred to as a sumping operation in which the auger cutters are moved generally longitudinally into the seam at one side of the face. The second operation is to move the cutters transversely across the face after sumping has been accomplished. As previously indicated, these movements are accomplished with the use of the cable and drum assemblies on opposite sides of the frame by anchoring the free ends of the cables at appropriate positions within the mine by conventional jacks or the like extendible into engagement between the mine roof and floor and retractable out of such engagement. Thus each sumping movement as well as each lateral movement required a new cable jack setting. Normal advancement required that the crew include two jack setters operating quite close to the face and, quite often, close to the cutters themselves.

An object of the present invention is to provide an improved method of advancing a continuous miner of the type described into the coal seam which eliminates the aforesaid sumping operation and so simplifies the overall operation as to eliminate the need for the two jack setters heretofore employed.

Another object of the present invention is to provide a machine of the type described with the capability of advancing in accordance with this improved procedure by a simple modification of the existing structure thereof thereby making it possible to achieve the afore said operational advantages without substantial increases in manufacturing costs in terms of new equipment and to modify existing machines without substantial retrofit costs.

In accordance with the principles of the present invention these objectives are obtained by the simple provision of a pair of jack assemblies on opposite sides of the rear end portion of the continuous miner frame which are extendible into engagement between the mine roof and floor and retractable out of engagement therewith. The provision of such jack assemblies provides the operator with the capability of restricting the movement of the frame to a pivotal movement within the mine about an axis substantially coincident with an extended one of the jack assemblies and to thereby effect such pivotal movement with the use of a single cable and drum assembly. By mounting the jack assemblies on opposite sides of the frame, this pivotal movement can be alternately performed about automatically properly spaced axes which provide for advancement in the following manner in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof. A complete cycle of operation beginning in such a seam with the continuous miner positioned adjacent one end of the arcuate face can be performed in essentially two steps. The first step is to effect a pivotal movement of the continuous miner across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in adirection toward the other end thereof to progressively remove a section of coal from the'seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about the spaced axis of pivotal move ment. The second step is to effect a pivotal movement of the continuous miner across the advanced face from the other end to a position adjacent the one end about an axis spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward the one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement.

By this procedure, not only is it possible to'obtain a substantial saving in the time required to complete an operating cycle, but the 'cycle can be completed in a simple fashion without the necessity of the two jack setters. With the present procedure, no one works forward of the pull ropes or cables and the entire crew is able to stay further from the face and the cutting augers. Furthermore, the cutting cycle provides for a more rapid movement with a more thorough clean-up and more uniform conveyor loading throughout the cycle resulting in greater tonage. The semi-circular coal face offers better roof support and ventilation. The restricted pivotal movement of the continuous mining machine presents a much more favorable situation within the mine, since only the front of the machine has substantial movement. This permits permanent roof supports to be set closer to the face and the use of fewer temporary supports during operation.

The procedure can be further simplified from a manual labor standpoint by mounting the anchor jacks for the ends of the cables on mobile power driven vehicular frames. With this arrangement not only is the normal operating cycle facilitated, but a greater degree of mobility of the machine is provided when it becomes necessary to move the machine within the mine from one operating face to a remote operating face or the like.

These and other objects of the present invention will become more apparent during thecourse of the following detailed description and appended claims. The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.

In the drawings:

FIGS. 1A, 1B and 1C are a series of top plan views showing a mining machine embodying the principles of the present. invention'progressively advancing within a coal mine by the procedures according to the present invention;

FIGS. 2A, 2B, 2C, 2D and 2E are views similar to those of FIG. 1 illustrating the prior art procedures for advancing a known dual auger continuous mining machine within a coal. mine;

FIG. 3 is a fragmentary top plan view of the frame of the mining machine illustrating the modifications thereto in accordance with the improvements of the present invention;

FIG. 4 is a side elevational view of the structure illustrated in FIG. 3;

FIG. 5 is an enlarged fragmentary sectional view taken along the line 5-5 of FIG. 3;

FIG. 6 is a top plan view of a power driven mobile vehicular frame and anchorjack assembly embodying the principles of the present invention; and

FIG. 7 is a side elevational view of the assembly shown in FIG. 6.

Referring now more particularly to FIG. 1' of the drawings, there is shown therein a continuous mining machine, generally indicated at 10, of the dual auger type to which the improvements of the present invention have been applied. It will be understood that the principles of the present invention have applicability to other types of continuous mining machines, nevertheless particularly advantageous results are achieved in conjunction with known dual auger type continuous machines, which include the Wilcox MARK and the Jeffrey IOOL, as aforesaid.

The construction and mode of operation of the known Wilcox continuous mining machine is illustrated in FIG. 2, the machine being generally designated by the reference character 10'. Since the present invention involves modification of the known machine 10', it is appropriate to first describe the basic components of the known machine 10' which areretained within the machine 10 of the present invention. For present purposes corresponding components of the machine 10 of the present invention will be indicated by numerals corresponding to primed numerals of the known machine 10'.

The machine 10 includes a main frame 12' providing a lower surface of generally planar configuration which engages the mine floor so as to support the machine thereon. Disposed forwardly of the frame 12' is a coal cutting and conveying mechanism in the form of two auger cutters 14'. The auger cutters 14' are oppositely pitched with respect to each other and are mounted on the frame 12 in forwardly disposed relation with their axes of rotation extending generally horizontally forwardly in horizontally spaced parallel relation. The auger cutters 14' are mounted for power driven rotation abouttheir axes in opposite directions and for independent vertical movement, as by a pivotal action about an axis parallel to the respective axis of rotation. Each auger cutter 14' includes a pair of helical blades having a series of cutting teeth at the forward end thereof and a series of cutting teeth extending outwardly of the periphery thereof in longitudinally spaced relation therealong. It will be understood that the machine 10 includes a suitable source of power such as an electric motor which serves to effect the rotational movement of the augers and that the machine is provided with hydraulic rams or the like for effecting the independent vertical movement of each auger cutter.

The machine 10' is also provided with means for advancing the auger cutters into a coal seam so that the coal engaged by the auger cutters is loosened from the vein and conveyed outwardly of the face. The advancing means, as shown, includes a power driven winch or drum 16 on each side of the frame 12' and a cable 18' woundaround each drum 16' so that a free end portion extending from the associated drum and selectively around appropriate forwardly and rearwardly mounted pulleys can be suitably anchored at its extremity, as by anchor jacks 20'. Each anchor jack 20 is of conventional construction operable to be extendible into engagement between the mine roof and floor and retractable out of such engagement.

The mining machine 10' also includes suitable conveyor means 22' on the main frame 12' for moving the coal removed from the vein by the auger cutters M to a position rearwardly of the frame. The coal issuing from the rear end of the conveyor means 22' is preferably handled in a continuous fashion. As shown in FIG. 2, a bridge conveyor assembly, generally indicated at 24', is articulately connected at its forward end to the rearward end of the conveyor means 22' and has its rearward end connected to a second conveyor assembly 26' which, in the case of the Wilcox equipment, is referred to as a Universal Advance Conveyor". This conveyor is, in turn, mounted on an extendible floor conveyor assembly, generally indicated at 28 (e.'g. the Wilcox Low-Lo Belt Conveyor). The construction and mode of operation of the overall equipment is disclosed in the aforesaid Wilcox US. Pat. Nos. 3,026,098; 3,282,403; 3,305,268 and 3,306,667, all of which are hereby incorporated by reference into the present specification.

For purposes of the present application it is important to'note the mode of operation of the known machine in order to fully understand and appreciate the improvements thereover which are accomplished by practicing the principles of the present invention. As

by the use of posts and roof bolts with installation of the latter being facilitated by the use of a power driven mobile roof bolting mechanism or assembly 30', which, as shown, is of the type manufactured and sold by the Wilcox Manufacturing Co. under the trade name Wilcox Compact Roof Bolter. In the drawings, a roof bolt support is indicated by a square symbol, a post support is indicated by a circle within a rectangle, and appropriate temporary support is indicated by a dot within a circle.

For the sake of convenience, the operating cycle may be considered to commence with the machine It) at a position adjacent one end of the face-as, for example, the left-hand end as shown in FIG. 1A. With the machine in this position, the anchor jacks are set in the position shown with the cables 18' extending around the rear pulleys. The sumping operation is accomplished by actuating the drums 16' to wind up the cables thereon, which has the effect of moving the machine longitudinally forwardly so that the auger cutters 14' move into the vein with a sumping action. It should be noted that during this operation, the auger cutters are each engaging coal throughout the full diameter dimension thereof so that there is a relatively high amount of coal being moved outwardly of the face during the sumping operation.

After the sumping operation has been completed, the roof bolting mechanism 30' is utilized to install the first roof bolt, as can be clearly seen from FIG. 2B. The next operation is to set the anchor jacks 20 in the position substantially as shown in FIG. 2C, which will enable actuation of the drums in opposite directions to effect lateral movement of the machine across the face. The initial lateral movement is performed in conjunction with an appropriate raising and lowering of the augers for the purpose of cutting out the full height of the seam at the position of sumping. This operation is necessary since, during the sumping operation, only two substantially cylindrical cores are removed from the vein. This squaring off of the corner" can be accomplished in any desired fashion and normally will entail lateral movement of the entire machine both to the right and then to the left for purposes of insuring the best cleanup action. At the end of this operation, the second roof bolt is installed as indicated by the position of the roof bolting assembly 30' in FIG. 2C.

In order to complete the lateral movement of the machine across the face, the left hand anchor jack 20' must again be re-set in the position as shown in FIG. 2D. Prior to the completion of this operation, the third roof bolt is installed, as indicated by the position of the roof bolting assembly 30' in FIG. 2D. Finally, after moving the assembly 30' back out of the way, the lateral movement of the machine to the right is completed and here again, it will be noted that the auger cutters must be moved vertically to insure that this corner of the vein is squared off.

At the completion of the movement of the machine laterally across the face to the right, the same procedure is then undertaken in the reverse direction to the left across the face to complete a full cycle. It should be noted that in the normal operation of the cycle as described above, the setting of the roof jacks is accomplished by a worker on each side of the machine. In almost every instance, the position at which the anchor 5 jacks must be set within the mine is close to the face,

thus subjecting these workers to the hazards of concentrated coal. dust and unsupported roof conditions. Moreover, since the coal which is moved outwardly of the face by the auger cutters during the sumping operation is conveyed outwardly by full peripheral confinement, whereas the coal moved outwardly of the face during the movement of the machine across the face is conveyed outwardly without such confinement, the outwardly conveyed load which must be handled by the conveying means 22 of the machine can vary to a considerable extent during the overall operation depending upon the rate of movement across the face. Moreover, as this movement increases an increasing amount of coal is left on the floor inwardly of the face to be picked up by the clean-up scrolls or the next pass. However, the clean-up scrolls cannot get all of the coal left be cause of their shorter longitudinal reach. This uneven and incomplete flow of coal to the conveyor means 22 makes it desirable to utilize the anchor jack operators to assist in clean-up by the use of manual shovels.

The apparatus 10 as shown in FIG. lembodies all of the components of the machine 10' as described above. The modifications which are required in accordance with the principles of the present invention are essentially additional components which can be added to the basic machine. These added components are best shown in FIGS. 3-51 I In FIG. 3, the rear end portion of the frame 12 of the machine 10 is shown. The rear end portion includes a bottom plate 32 which is shown'in unshaded lines in FIG. 3. This known frame construction 32 is modified in accordance with the principles of the present invention by the provision of an extension bottom plate 34, the forward edge of which is shaped to conform with the rear edge of the plate 32 and rigidly attached thereto as by welding or the like. In order to reduce weight without sacrificing strength where needed, the extension plate 34 is provided with a pairof circular openings 36 in the central portion thereof. Fixed to the rear end of the plate 34 on opposite sides thereof is a pair of vertically extending rigid sleeves 38. As shown, each of the sleeves 38 is suitably welded along its lower edge with the conformingly-shaped rear edge of the plate 34 and extends upwardly therefrom. The mounting of each sleeve 38 is suitably reinforced as by an inverted U-shaped strengthening plate construction at) welded at its rearward end with the associated sleeve and at its forward end with the upper surface of the plate 32. Each reinforcing plate construction is likewise welded to the upper surface of the extension plate 34.

Each sleeve 38- serves to pivotally support a pivot unit, generally indicated at 42 which is extensible into engagement between the mine roof and floor and retractable from such engagement. As best shown in FIG. 5, each pivot unit 42 includes a hydraulic ram, generally indicated at 44, which includes the usual cylinder 46, piston 48 and piston rod 5t]. In the embodiment shown, the cylinder 46 includes a longitudinally extending lug 52 on the exterior periphery thereof within which the inlet and outlet hydraulic passages to the op posite ends of the cylinder pressure chamber are provided. As shown in FIG. 5, the hydraulic ram M is positioned so that the piston rod 50 extends downwardly through the cylinder. The lower end of the piston rod 50 is connected with a floor-engaging member 54 which is loosely disposed within an associated sleeve 38. As shown, each floor-engaging member 54 is of a generally cup-shaped configuration, having a circular bottom wall 56 and a cylindrical peripheral wall which is longitudinally slotted, as indicated at 58, to slidably receive the cylinder lug 52. Rigidly secured to the upper surface of the bottom wall 56 is a sleeve or collar 60 of a size to receive the lower end of the piston rod 50. The piston rod is connected with the sleeve as by a pin 62 which extends through registering openings formed transversely through the sleeve and the rod. The cylindrical wall of the floor-engaging member 54 is suitably apertured to permit installation of the pin.

Each pivot unit 42 also includes a roof-engaging member 64 which, as shown, includes a slotted socket portion 66 on its lower end for engagement over the upper end of the cylinder 46 and an upper portion defining an upwardly facing roof-engaging conical surface 68.

It will be understood that a source of hydraulic fluid under pressure carried by the machine frame is communicated with each hydraulic ram 44 so as to be controlled by the operator. This entails extending a pair of

hydraulic lines

70 and 72 to each hydraulic ram. In order to prevent an unlimited relative rotational movement of each pivot unit 42 with respect to the associated mounting sleeve 38 thereof, which might result in the entanglement or fouling of the

hydraulic lines

70 and 72, suitable rotational stop means is provided. in the embodiment shown, it will be noted that the engagement of the cylinder lug 52 within the slots of the

members

54 and 64 serves to prevent relative rotational movement between the hydraulic ram 44 and the

members

54 and 64 while permitting relative vertical movement therebetween. Since the

members

54 and 64 are effectively rotationally keyed to the hydraulic ram 44, provision of suitable stop means on either of the

members

54 or 64 with respect to the associated sleeve 38 or frame part 34 will serve to effectively limit the rotational movement of each pivot unit 42. In the embodiment shown, the stop means for each pivot unit 42 comprises a post 74 rigidly secured to the exterior periphery of each sleeve 38 and extending upwardly therefrom. Formed on the upper exterior periphery of each floor engaging member 54 is an arcuate stop element 76, having radial ends 78 adapted to engage the associated post 74.

It will be understood that the pivot units 42 thus provided on opposite sides of the rear end portion of the frame of the machine 10 cooperatively function with the drums and

cables

16 and 18 on each side of the frame as the advancing means for the machine. This ad vancing means enables the machine to be operated in accordance with the method of the present invention in a manner which eliminates the sumping action heretofore required and permits a complete cycle of operation with a simple two-step procedure. The first step is to effect a pivotal movement of the continuous miner across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward the other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about the spaced axis of pivotal movement. The second step is to effect a pivotal movement of the continuous miner across the advanced face from the other end to a position adjacent the one end about an axis spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward the'one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement.

A specific example of the cycle of operation embodied in the above-identified method utilizing the machine 10 of the present invention is illustrated in FIG. 1. It will be understood that the components which comprise the advancingmeans as previously indicated areutilized with anchor jacks of the type described with respect to the known machine 10'. However, the

apparatus and procedure illustrated in FIG. 1 includes the provision of a pair of power driven mobile jack assemblies, generally indicated at 80, which are utilized in lieu of the known anchor jacks described in connection with the structure and operation of the known machine 10. Consequently, before proceeding with the description of the operation as illustrated in FIG. 1 it is first appropriate to obtain an understanding of the construction and operation of the assemblies 80, a preferred embodiment of which is illustrated in FIGS. 6 and 7.

ln general, it can be stated that each power driven mobile jack assembly is constructed in a manner similar to the Wilcox Compact Roof Bolter previously described and indicated in FIG. 2 by the numeral 30'. Thus, as shown, each assembly 80 includes a main frame, generally indicated at 82, which has mounted on opposite sides of the central portion thereof a pair of gear case assemblies 84, each of which is drivinglyconnected with apair of longitudinally aligned front and

rear wheels

86 and 88. Each gear case assembly 84 is adapted to be driven by a hydraulic motor, generally indicated at 90, and each hydraulic motor is, in turn, driven by a hydraulic pump, generally indicated at 92 (see FIG. 6). The hydraulic pump 92 is, in turn, driven by an electrical motor 94 in accordance with conventional practice.

Mounted on the frame 82 toward the rear end thereof are suitable control valve actuators 96 which can be manually moved by the operator for the purpose of controlling the forward and rearward movement of the frame through desired movement of the

wheels

86 and 88 by the gearcase assemblies 84 and hydraulic motors 90. The arrangement as shown is a four wheel drive assembly in which turning of the vehicle frame is accomplished by actuation of the controls 86 in generally conventional fashion.

The vehicle frame 82 includes a pair of transversely spaced forwardly extending anchor jack mounting plates 98. The mounting plates 98 serve to operatively receive and support an anchor jack assembly, generally indicated at 100, which is constructed in a manner similar to the pivot units 42 previously described. Thus, each assembly 100 includes a hydraulic ram 102, a floor-engaging member 104 and a roof-engaging memher 106. The arrangement differs from that previously described in that the unit is mounted on the plates 98 by a collar 108 which engages over the central portion of the cylinder of the hydraulic ram 102 and has a pair of trunions 110 extending radially outwardly therefrom at diametrically opposed positions for engagement within upwardly extending openings 112 formed in the upper surface of the mounting plates 98. In addition, a collar 114 is swivelly mounted on the lower exterior periphery of the floor engaging member 104-. The swivel collar 114 is provided with a hook 116 for receiving the end of the cable 18 associated therewith.

Referring now more particularly to FIG. 1, the cycle of operation will be conveniently begun with the machine 10 positioned adjacent one end of a previously formed face, indicated at F1 in FIG. 1A. It will be noted that the face F1 is generally arcuate in configuration about an axis indicated at A1 which is coincident with the axis of the left-hand pivot unit 4-2 with the machine in the position as shown in FIG. 1A. It will be under-- stood that the position as shown in FIG. 1A is the position the machine assumes at the end of a preceding cycle. The free ends of the respective cables 18 are connected with the respective swivel hooks 116 of the respective assemblies 80. The left-hand auger cutter 14 is normally disposed in a raised position at the end of this cycle and the right-hand auger cutter 14 is disposed in a lowered position adjacent the floor. Thus, there is a ledge of coal which extends from the inner periphery of the right-hand auger cutter to the side wall of the entry being formed below the periphery of the lefthand auger cutter.

Operation is commenced by disengaging the drive to the right-hand drum 16 and moving the assembly 80 adjacent the right-hand side wall to the position as shown in FIG. 1A and then actuating the anchor jack assembly 100 thereof to extend the same into engagement between the mine roof and floor. Next, the operator of the machine actuates the appropriate controls to disengage the left-hand drum 16 and to engage the right-hand drum 16. Either after this operation has been completed, or before, the operator of the machine actuates the appropriate controls to extend the righthand pivot unit $2 and retract the left-hand pivot unit 42.

It will be noted that the extension of the right-hand pivot unit 42 now restricts the movement of the entire machine about a pivotal axis A2 coincident with the axis of the right-hand pivot unit, which is spaced from the axis All of the face F1 both in a direction laterally toward the right-hand side wall of the entry being formed and in a direction toward the face Fl. Prior to the actuation of the right-hand drum 16 to commence the pivotal movement of the machine, the right-hand auger cutter 14 which was previously in a lowered position is raised so as to engage the roof of the mine seam and the left-hand auger is lowered to a position adjacent the floor. Actuation of the right-hand drum 16 to wind up the cable will now effect a pivotal movement of the entire machine about the axis A2 in a clockwise direction as viewed in FIG. 1, or toward the right, during which movement the left-hand cable 18 is allowed to pay out from the disengaged left-hand drum 16. It will be noted that during the initial portion of this movement the left-hand auger cutter 141 will cut the ledge of coal adjacent the left-hand side wall and the loose coal beyond the ledge which was previously left during the latter cycle of operation. As the machine is moved arcuately across the face F1, the cutters move inwardly of the face a distance which progressively increases as the arcuate movement progresses. When the machine has reached the opposite side wall, as shown in FIG. 18, a section of coal has been removed from the seam outwardly of the face F1 which is substantially arcuately wedge-shaped in configuration and a new face F2 is defined which is generally arcuate about the axis A2. Here again, a ledge of coal is left below the righthand auger cutter extending from the right-hand side wall to the righthand periphery of the left-hand auger cutter.

When the machine 10 reaches the position as shown in FIG. 1B, the first step of the cycle is completed and the jack assembly of the left-hand assembly 8h is retracted so that the latter can be moved into the position shown in FIG. 1C, at which position, the jack as sembly 100 thereof is again extended into engagement between the mine roof and floor. The operator of the machine then actuates the hydraulic controls to retract the right-hand pivot unit 42 and to extend the left-hand pivot unit 42 into engagement between the mine roof and floor. This movement establishes an axis A3 of pivotal movement of the machine during the second step which is spaced laterally and toward the face F2 from the axis A2. As before, the vertical position of the auger cutters 14 is reversed, that is, the left-hand auger is moved from a lowered position to a raised position and the right-hand auger cutter is moved from a raised position to a lowered position. The left-hand drum 16 is then engaged and actuated to commence movement of the machine in a counter-clockwise direction as viewed in FIG. 1B, or the left, during which movement the right-hand cable 18 is allowed to pay out from the disengaged right-hand drum 16. Here again, during the initial movement, the'lowered right-hand auger M removes the coal in the ledge which has been previously left and as the machine 10 proceeds across the face a section of coal is removed from the seam which extends inwardly of the face F2 a distance which progressively increases as the arcuate movement to the left proceeds. As soon as the machine reaches the left-hand end wall, the cycle of operation is completed and here again, it will be noted that movement of the machine across the face to the left has removed asection of coal which is of generally arcuate wedge-shaped configuration and defines a new arcuate face, F3, which is arcuate about the axis A3.

There are many significant advantages which are achieved by advancing the machine 10 in accordance with the principles of the present method utilizing the modified structure of the present apparatus as previously described in comparison with the known method of advancing the known machine 111. At the outset, it will be recognized that the procedure and apparatus for advancingin accordance with the present invention has the effect of creating an arcuate face in the coal seam. It is known that such a face configuration provides a more favorable roof support than is the case with relatively straight faces. Moreover, as can be clearly seen from the illustrations contained in FIG. 1, no personnel are required to work in close proximity to the face or the cutting mechanism of the machine, as is the case with the known procedure. This enables operation without the necessity of providing roof support near the face and, of course, provides the further advantage of eliminating the need to subject workers to the inherent dangers which exist close to the face, such as concentrated coal dust and falling rock from the roof. Moreover, the arcuate configuration of the face is advantageous from the standpoint of air circulation in comparison with straight faces.

All of these advantages make it possible to advance the machine without the need of providing two separate anchor jack workers, such as was previously required in the operation of the machine 10. The roof bolting operation can be carried on at a. position outwardly of the face toward the rear end of the machine and this worker can also operate the assemblies 80. Moreover, the operation of the machine is greatly simplified since the elimination of the sumping operation eliminates the necessity of the operator to square off the corners which was previously required. This operation is automatically accomplished during the present operating cycle in a manner described above. More over, this arrangement makes the flow of coal to the conveyor 22 of the machine much more uniform than was the case during the operating cycle of the known machine 10'. Finally, it will be noted that the rear end of the machine frame 12 does not have the same degree of movement as is the case with the machine 10. In this regard, however, it will be noted that the machine 10 is still fully capable of being operated in the same fashion as the known machine 10'. In summary, it can be stated that by utilizing the principles of the present invention a much more rapid recovery of coal can be obtained with less labor than heretofore required with a much more uniform flow of coal during the operation and with less clean-up required. Indeed, by utilizing the principles of the present invention the clean-up problem is sufficiently alleviated as to eliminate the need for any manual clean-up in the face area.

It will be understood that the position of the pivot units 42 on the machine frame 12 serve to automatically establish both the axis of pivotal movement across the face and the next axis of movement upon the completion of the first movement. The cable and drum arrangement for effecting the pivotal movement is preferred but other means may be utilized. Moreover, with the use of the cable and drum assemblies it is possible to effect a plurality of operating cycles without advancing the anchor settings, as indicated above.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodimenthas been shown and described for the purpose of illustrating the functional and structural principles of this invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is:

1. A continuous mining machine for removing coal from a coal seam having a shortwall face extending concavely arcuate from a side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof, said machine comprising:

a. an elongated frame,

b. power driven cutting and conveying means carried by said frame in forwardly disposed relation thereto and operable during relative movement of said frame with respect to said face to cut a room section in the coal seam inwardly of the face thereof while continuously conveying the cut coal outwardly of the face,

0. conveyor means operatively associated with said frame for continuously moving the coal rearwardly away from the mine face which is cut and conveyed outwardly of the mine face during the formation of said room section by said cutting and conveying means,

d. first means for effecting a pivotal movement of said frame and said cutting and conveying means from a position adjacent one end of said face across the face to a position adjacent the other end thereof about an axis adjacent the rear portion of the frame spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively'in the direction of movement across the face and to progressively define an adv anced face which extends concavely arcuate about said spaced axis of pivotal movement, and

e. second means for effecting a pivotal movement of said frame and said cutting and conveying means acrossthe advanced face from said other end to a position adjacent said one end about an axis adjacent the rear portion of the frame spaced from the axis of said advanced face both in a direction toward the advanced face and in a-direction toward said one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement,

said first pivotal movement effecting means including a first vertically extensible and retractable pivot unit carried by the rear end portion of said frame at the side thereof adjacent the other end of said face for extensible engagement between the mine roof and floor and retractable disengagement between the mine roof and floor, said second pivotal movement effecting means including a second vertically extensible and retractable pivot unit carried by the rear end portion of said frame at the side thereof adjacentthe one end of said face for extensible engagement between the mine roof and floor and retractable disengagement between the mine roof and floor.

2. A continuous mining machine as defined in claim 1 wherein each of said pivot units includes a hydraulic ram.

3. A continuous mining machine as defined in claim 2 wherein each of said pivot units includes an annular floor engaging member, a vertically extending sleeve fixed to said frame receiving said floor engaging member for limited vertical movement and limited pivotal movement with respect thereto, and a roof engaging member, said hydraulic ram including a piston rod connected at its lower end to said floor engaging member and a cylinder mounted for non-rotating vertical movement with respect to said floor engaging member and connected at its upper end to said roof engaging member.

cludes a second power driven drum on the side of the frame adjacent said second pivot unit, and a second length of cable wound around said second drum and having an end portion extending therefrom adapted to be anchored adjacent the other end of said face.

5. A continuous mining machine as defined in claim 4 wherein said first pivotal movement effecting means further includes a first anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and means connecting the end portion of said first cable with said first anchoring unit and wherein said second pivotal movement effecting means further includes a second anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and means connecting said second cable with said second anchoring unit.

6. A continuous mining machine as defined in claim S-Wherein each of said anchoring units is mounted on a mobile power driven vehicle.

7. A continuous mining machine as defined in claim 6 wherein said cutting and conveying means comprises a pair of oppositely pitched auger cutters, each including a pair of longitudinally spaced helical blades having cutting means disposed adjacent the forward end thereof and cutting teeth extending outwardly of the longitudinal periphery of said blades in longitudinally spaced relation, and means mounting said auger cutters for rotational movement in opposite directions about transversely spaced generally horizontally extending axes and for independent vertical movement.

8. Method of advancing a continuous miner of the type including a pair of horizontally spaced vertically movable oppositely pitched and oppositely rotatable auger cutters in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly "thereof which comprises the steps of positioning the continuous miner adjacent one and of the arcuate face of the coal seam with the auger cutters adjacent said one end in a lowered position and the other auger cutter in a raised position, effecting a pivotal movement of the continuous miner with said auger cutters maintained substantially in said positions across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof, while continuously rotating said auger cutters in opposite directions to establish-cutting actions of the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to said direction of pivotal movement and outwardly and in the direction of pivotal movement to thereby (l) progressively remove a section of coal from the seam which extends inwardly of the face a distance which in creases progressively in the direction of movement across the face except for a bottom ledge adjacent said other side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (2) progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement except for the portion of the face defined by said bottom ledge,-

effecting vertical movements of said auger cutters such that the raised auger cutter is in a lowered position and the lowered auger cutter is in a raised position,

effecting a pivotal movement of the continuous -miner with the auger cutters maintained substantially in their positions of vertical movement, as aforesaid, across the advanced face from said other end to a position adjacent said one end about an axis spaced by the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof while continuously rotating said auger cutters in opposite directions to establish cutting actions by the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to the direction of the last mentioned pivotal movement and outwardly and in a direction of the last mentioned pivotal movement to thereby (l) progressively remove said bottom ledge by the cutting and conveying action of said lowered auger cutter, (2) progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the ad vanced face except for a bottom ledge adjacent said one side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (3') progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement except for the face portion defined by said bottom ledge.

9. A continuous mining machine for removing coal from a coal seam having a shozrtwall face extending concavely arcuate from a side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof, said machine comprising:

a. an elongated frame, I

b. a pair of oppositely pitched auger cutters, each including a pair of longitudinally spaced helical blades having cutting means disposed adjacent the forward end thereof and cutting teeth extending outwardly of the longitudinal periphery of said blades in longitudinally spaced relation,

c. means mounting said auger cutters on said frame in forwardly disposed relation thereto for rotational movement in opposite directions about transversely spaced generally horizontally extending axes and for independent vertical movement,

d. means carried by said frame for rotating said auger cutters in said opposite directions,

e. means carried by said frame for effecting vertical movement of each of said auger cutters between raised and lowered positions,

f. first means for effecting a pivotal movement of said frame with said auger cutters maintained substantially in said positions across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof with said auger cutters rotating in opposite directions to establish cutting actions of the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to said direction of pivotal movement and outwardly and in the direction of pivotal movement to thereby (l) progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face except for a bottom ledge adjacent said other side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (2) progressively define an advanced face which extends concavely arcuate about said'spaced axis of pivotal movement except for the portion of the face defined by said bottom ledge,

g. second means for effecting a pivotal movement of the continuous miner with said auger cutters maintained substantially in reversed. raised and lowered positions across the advanced face from said other end to a position adjacent said one end about an axis spaced by the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof with said auger cutters rotating in opposite directions to establish cutting actions by the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to the direction of the last mentioned pivotal movement and outwardly and in the direction of the last mentioned pivotal movement to thereby (l) progressively remove said bottom ledge by the cutting and conveying action of said lowered auger cutter, (2) progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face except for a bottom ledge adjacent said one side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (3) progressively define includes a first mobile power driven vehicle having a first anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and wherein said second pivotal movement effective means includes a second mobile power driven vehicle having a second anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor.

11. A continuous mining machine as defined in claim 9 wherein said first pivotal movement effecting means further includes a first power driven drum on the side of the frame adjacent said first pivot unit, and a first length of cable wound around said first drum and having an end portion extending therefrom adapted to be anchored adjacent the one end of said face and said second pivotal movement effecting means further includes a second power driven drum on the side of the frame adjacent said second pivot unit, and a second length of cable wound around said second drum and having an end portion extending therefrom adapted to be anchored adjacent the other end of said face.

12. A continuous mining machine as defined in claim 11 wherein said first pivotal movement effecting means further includes a first anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor means connecting the end portion of said first cable with said first anchoring unit and wherein said second pivotal movement effecting means further includes a second anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and means connecting said second cable with said second 7 anchoring unit.

13. A continuous mining machine as defined in claim

Claims

1. A continuous mining machine for removing coal from a coal seam having a shortwall face extending concavely arcuate from a side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof, said machine comprising: a. an elongated frame, b. power driven cutting and conveying means carried by said frame in forwardly disposed relation thereto and operable during relative movement of said frame with respect to said face to cut a room section in the coal seam inwardly of the face thereof while continuously conveying the cut coal outwardly of the face, c. conveyor means operatively associated with said frame for continuously moving the coal rearwardly away from the mine face which is cut and conveyed outwardly of the mine face during the formation of said room section by said cutting and conveying means, d. first means for effecting a pivotal movement of said frame and said cutting and conveying means from a position adjacent one end of said face across the face to a position adjacent the other end thereof about an axis adjacent the rear portion of the frame spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement, and e. second means for effecting a pivotal movement of said frame and said cutting and conveying means across the advanced face from said other end to a position adjacent said one end about an axis adjacent the rear portion of the frame spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement, said first pivotal movement effecting means including a first vertically extensible and retractable pivot unit carried by the rear end portion of said frame at the side thereof adjacent the other end of said face for extensible engagement between the mine roof and floor and retractable disengagement between the mine roof and floor, said second pivotal movement effecting means including a second vertically extensible and retractable pivot unit carried by the rear end portion of said frame at the side thereof adjacent the one end of said face for extensible engagement between the mine roof and floor and retractable disengagement between the mine roof and floor.

4. A continuous mining machine as defined in claim 3 wherein said first pivotal movement effecting means further includes a first power driven drum on the side of the frame adjaCent said first pivot unit, and a first length of cable wound around said first drum and having an end portion extending therefrom adapted to be anchored adjacent the one end of said face and said second pivotal movement effecting means further includes a second power driven drum on the side of the frame adjacent said second pivot unit, and a second length of cable wound around said second drum and having an end portion extending therefrom adapted to be anchored adjacent the other end of said face.

6. A continuous mining machine as defined in claim 5 wherein each of said anchoring units is mounted on a mobile power driven vehicle.

8. Method of advancing a continuous miner of the type including a pair of horizontally spaced vertically movable oppositely pitched and oppositely rotatable auger cutters in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof which comprises the steps of positioning the continuous miner adjacent one and of the arcuate face of the coal seam with the auger cutters adjacent said one end in a lowered position and the other auger cutter in a raised position, effecting a pivotal movement of the continuous miner with said auger cutters maintained substantially in said positions across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof, while continuously rotating said auger cutters in opposite directions to establish cutting actions of the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to said direction of pivotal movement and outwardly and in the direction of pivotal movement to thereby (1) progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face except for a bottom ledge adjacent said other side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (2) progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement except for the portion of the face defined by said bottom ledge, effecting vertical movements of said auger cutters such that the raised auger cutter is in a lowered position and the lowered auger cutter is in a raised position, effecting a pivotal movement of the continuous miner with the auger cutters maintained substantially in their positions of verTical movement, as aforesaid, across the advanced face from said other end to a position adjacent said one end about an axis spaced by the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof while continuously rotating said auger cutters in opposite directions to establish cutting actions by the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to the direction of the last mentioned pivotal movement and outwardly and in a direction of the last mentioned pivotal movement to thereby (1) progressively remove said bottom ledge by the cutting and conveying action of said lowered auger cutter, (2) progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face except for a bottom ledge adjacent said one side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (3) progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement except for the face portion defined by said bottom ledge.

9. A continuous mining machine for removing coal from a coal seam having a shortwall face extending concavely arcuate from a side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof, said machine comprising: a. an elongated frame, b. a pair of oppositely pitched auger cutters, each including a pair of longitudinally spaced helical blades having cutting means disposed adjacent the forward end thereof and cutting teeth extending outwardly of the longitudinal periphery of said blades in longitudinally spaced relation, c. means mounting said auger cutters on said frame in forwardly disposed relation thereto for rotational movement in opposite directions about transversely spaced generally horizontally extending axes and for independent vertical movement, d. means carried by said frame for rotating said auger cutters in said opposite directions, e. means carried by said frame for effecting vertical movement of each of said auger cutters between raised and lowered positions, f. first means for effecting a pivotal movement of said frame with said auger cutters maintained substantially in said positions across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof with said auger cutters rotating in opposite directions to establish cutting actions of the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to said direction of pivotal movement and outwardly and in the direction of pivotal movement to thereby (1) progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face except for a bottom ledge adjacent said other side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (2) progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement except for the portion of the face defined by said bottom ledge, g. second means for effecting a pivotal movement of the continuous miner with said auger cutters maintained substantially in reversed raised and lowered positions across the advanced face from said other end to a position adjacent said one end about an axis spaced by the axis of said advanced face both in a direction toward the advanced face And in a direction toward said one end thereof with said auger cutters rotating in opposite directions to establish cutting actions by the raised and lowered auger cutters directed respectively downwardly and upwardly and conveying actions directed respectively outwardly and in a direction opposed to the direction of the last mentioned pivotal movement and outwardly and in the direction of the last mentioned pivotal movement to thereby (1) progressively remove said bottom ledge by the cutting and conveying action of said lowered auger cutter, (2) progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face except for a bottom ledge adjacent said one side wall which is left by virtue of the leading relationship of the raised auger and the trailing relationship of the lowered auger cutter and (3) progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement except for the face portion defined by said bottom ledge, and h. conveyor means operatively associated with said frame for continuously moving the coal rearwardly away from the mine face which is removed from the mine face during the formation of said room sections by said auger cutters.

10. A continuous mining machine as defined in claim 9 wherein said first pivotal movement effecting means includes a first mobile power driven vehicle having a first anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and wherein said second pivotal movement effective means includes a second mobile power driven vehicle having a second anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor.

12. A continuous mining machine as defined in claim 11 wherein said first pivotal movement effecting means further includes a first anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor means connecting the end portion of said first cable with said first anchoring unit and wherein said second pivotal movement effecting means further includes a second anchoring unit extensible for engagement between the mine roof and floor and retractable for disengagement between the mine roof and floor and means connecting said second cable with said second anchoring unit.

13. A continuous mining machine as defined in claim 12 wherein each of said anchoring units is mounted on a mobile power driven vehicle.