US3433529A

US3433529A - Longwall miner having cutter guided along mine face,curved corner section and side face

Info

Publication number: US3433529A
Application number: US657281A
Authority: US
Inventors: Walter Mueller; Hugo Alfs; Robert Von Der Lippe
Original assignee: MAS FAB MOENNINGHOFF
Current assignee: MAS FAB MOENNINGHOFF
Priority date: 1966-08-01
Filing date: 1967-07-31
Publication date: 1969-03-18
Anticipated expiration: 1986-03-18
Also published as: BE702152A; GB1193662A; DE1284382B

Description

March 18, 1969 w. MUELLER ET AL 3,433,529 LONGWALL MINER HAVING CUTTER GUIDED ALONG MINE FACE, CURVED CORNER SECTION AND SIDE FACE Filed July 31.

Sheet mvsu'roi BY WQM ATTORNEY March 18,1969 WM ELLER Em 3,433,529

LONGWALL MINER HAVING CUTTER GUIDED ALONG MINE FACE. CURVED Filed July 31. 1967 comma SECTION AND SIDE PAGE -Sheet 2 or2 INVENTOR$ United States Patent '0 M 70,418 US. Cl. 299-1 25 Claims Int. Cl. E21c 35/20, 41/04, 29/00 ABSTRACT OF THE DISCLOSURE The L-shaped frame of a coal mining apparatus has a longer leg which is parallel to and extends along the mine face of an underground excavation, a shorter leg which is adjacent to one side face of the excavation, and an arcuate part between the two legs. The cutter which travels back and forth along the frame between the free ends of the legs has a single drum-shaped radial tool whose axis is horizontal and respectively extends at right angles to the mine face and side face when the cutter respectively travels along the longer and shorter legs of the frame. An L-shaped conveyor is supported by the frame to transport material which is removed by the cutter, the material being transported in a direction from the free end of the longer leg toward the free end of the shorter leg. The tool is adjustable vertically and cuts the frame free when it completes one or more cycles be tween the free ends of the legs so that the frame can be shifted forwardly by a system of props and double-acting cylinders.

The frame carries a ramp which steers material resting on the mine floor onto the conveyor in response to forward movement of the frame, and the teeth of the tool are preferably arranged in helical formation to resemble a feed screw which transports fragments of material toward the ramp.

Background of the invention The present invention relates to improvements in apparatus for mining coal or the like in underground excavations. More particularly, the invention relates to improvements in apparatus which are movable stepwise toward the mine face and are equipped with reciprocatory cutters which travel back and forth along and remove layers of material from the mine face.

Heretofore known coal mining apparatus of the above outlined character normally comprise an elongated frame which extends in front of and substantially along the full length of the mine face, and an advancing system which transports the frame sideways along the mine floor and toward the mine face subsequent to removal of a material layer. The frame supports or is coupled with a material collecting conveyor which accepts removed material, and the frame also carries a reciprocatory cutter which is driven to travel back and forth in front of the mine face. As a rule, the frame is straight and is parallel to the mine face. The main difference between various types of conventional apparatus is in the design and mounting of their cutters.

In many presently employed coal mining apparatus, the cutter comprises a set of rotary drum-shaped cutting tools which are rotatable about horizontal or vertical axes and are adjustable up and down between a plurality of levels. Such design of the cutter renders it possible to change the length of the frame so as to allow for use of the apparatus 3,433,529 Patented Mar. 18, 1969 is relatively wide or relatively narrow underground excavations without unduly complicating the construction of the drive which reciprocates the cutter. Vertical adjustability of cutting tools renders it possible to remove material from relatively thin or relatively thick seams of coal.

A serious drawback of cutters with tools which rotate about vertical axes is that, for each adjustment in the level of the tools, the entire frame must be shifted away from the mine face and thereupon returned back sufficiently close to the mine face to place the tools into material removing position. Such shifting of the frame consumes much time and reduces the output of the apparatus. Furthermore, cutters with tools which rotate about vertical axes must employ two tools which are placed adjacent to each other in order to make sure that the tools remove sufficient quantities of material at the ends of the mine face so as to allow for forward movement of the frame. A drawback of such dual tools is that only one thereof removes material during travel along the major part of the mine face, i.e., the one or the other tool is used solely at the respective end of the mine face.

The situation is similar when the tools are arranged to rotate about horizontal axes which are normal to the mine face. Such tools must also be installed in pairs whereby one of the tools removes material at the longitudinal ends of the frame, i.e., in the region of the end turns of the material collecting and removing conveyor, in order to provide ample room for unimpeded stepwise advance of the frame. Frames with cutters having tools which rotate about horizontal axes need not be shifted away from the mine face when it becomes necessary to change the level of the tools; however, such tools must be capable of cutting in two directions, namely, during axial movement toward the mine face and also during sidewise travel along the mine face. In other words, the front face of each tool must be provided with blades or teeth which penetrate into the material when the tools move axially prior to travel along the mine face. The main material removing action is performed by teeth which extend radially of the tools. Since the capacity of tools depends on their diameter, it is desirable to utilize large-diameter tools. This brings about the drawback that axial penetration of relatively large drum-shaped tools into the material of the mine face consumes much time and energy with minimal removal of material. It was found that axial movement of tools into the mine face consumes a very large percentage of the time during which the apparatus is in actual use.

Summary of the invention It is an important object of the present invention to provide a novel and improved coal mining apparatus whose output is much higher than the output of aforedescribed conventional apparatus, which can work effectively with a single cutting tool, and which can remove material with negligible interruptions.

Another object of the invention is to provide an apparatus of the just outlined character with a novel frame, with a novel material collecting and evacuating conveyor system, and with a novel cutter.

A further object of the invention is to provide a coal mining apparatus which automatically removes sufiicient material at the ends of the mine face to permit stepwise advance of the frame and wherein such material removal takes place in the course of normal operation of the cutter.

An additional object of the invention is to provide an apparatus which can be rapidly and conveniently converted for removal of material in relatively narrow, relatively wide, relatively low or relatively high underground excavations.

A concomitant object of the invention is to provide a coal mining apparatus which removes material from the mine face with practically no interruptions at all and whose operation can be regulated automatically or semiautomatically by resorting to a simple and rugged programming system.

Another object of the invention is to provide an apparatus which can be manipulated by a small number of attendants, wherein the conveyor not only gathers but actually transports material away from the mine face, and wherein the cutter is designed in such a way that its tool can promote the movement of material onto the conveyor.

A further object of the invention is to provide an apparatus whose frame automatically transfers material onto the conveyor when it is caused to advance toward the mine face.

Briefly outlined, one feature of the present invention resides in the provision of an apparatus for mining coal or like materials in underground excavations bounded by a mine floor, a mine roof, a mine face, and two side faces. The apparatus comprises a preferably L-shaped frame which is assembled of articulately connected shorter sections and is shiftable along the mine floor toward the mine face, the frame including a relatively long first part extending in parallelism with and in front of the mine face, a shorter second part extending in parallelism with one of the side faces adjacent to one end of the mine face, and an arcuate third part which connects the first and second parts in the corner region between the mine face and the one side face, a cutter arranged to travel along the first, third and second parts and vice versa and having a single driven drum-shaped radial tool which rotates about a horizontal axis that is normal to the mine face when the tool travels along the first part and normal to the one side face when the tool travels along the second part of the frame, the tool forming an arcuate cutout in front of the third part during travel from the first to the second part of the frame or vice versa, means for adjusting the level of the tool at the free end of the first and/or second part, conveyor means preferably built into or supported by the frame and arranged to transport material which is removed by the tool by conveying such material along the mine face and thereupon along the one side face in a direction away from the mine face, and advancing means for shifting the frame toward the mine face when the tool has completed removal of a material layer along such mine face, along the surface bounding the aforementioned arcuate cutout, and along the front portion of the one side face.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved mining apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

Brief description of the drawing FIG. 1 is a side elevational view of a coal mining apparatus which embodies the present invention, the view being taken in the direction of arrows from the line I-I of FIG. 2 and showing the apparatus in front of the mine face in an underground excavation;

FIG. 2 is a top plan view of the apparatus, substantially as seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 is a larger scale end elevational view of the cutter, substantially as seen in the direction of the arrow III in FIG. 2.

Description of the preferred embodiments FIGS. 1 and 2 illustrate the front end of an underground coal mine shaft or excavation 1 which is bounded by a mine roof 2, a mine floor 3, a mine face 4, and two side faces 4a, 4b. The direction in which the improved material removing and collecting apparatus advances or walks in stepwise fashion is indicated by the arrow X.

The apparatus comprises a substantially L-shaped main support or frame 5 which includes a longer part or leg 5a extending in parallelism with the mine face 4, a shorter part or leg 51) which is normal to the leg 5a and extends in parallelism with the side face 4a, and an arcuate intermediate part So which connects the legs 5a, 5b adjacent to the front end of the side face 4a. The length of the leg 5b can be considerably less than that of the leg 5a; as a rule, it suffices if the length of the leg 5b approximates that of a cutting machine 14 (hereinafter called coal cutter or cutter for the sake of brevity). The three parts 5a-5c of the frame 5 are assembled of shorter sections 5A which are arranged end-to-end and are separable from each other to facilitate the assembly of a relatively large or relatively small frame. The removability of sections 5A is of particular importance in connection with the leg So because it enables the operators to assemble the frame with a longer leg 5a whose length equals the desired length of the mine face 4. The sections 5A are articulately coupled in such a way that they are free to move with reference to each other and to follow rather closely the outline of an uneven mine floor 3. Nevertheless, the connections between the sections 5A should be sufficiently rigid to allow for simultaneous transport of all sections in the direction of the arrow X whenever the cutter 14 has completed the removal of a layer along the mine face 4.

The frame 5 supports an endless material collecting and evacuating conveyor 6 which is preferably constituted by a so-called scraper flight conveyor having a single centrally located chain. One end turn 6a of the conveyor 6 is located at the free end of the leg 5a and a median portion of the conveyor 6 makes an are along the connecting part 50. The other end turn 6b of the conveyor 6 at the free end of the shorter leg 5b is raised (see FIG, 1); this end turn 6b carries a prime mover 6b which drives the chain of the conveyor 6 in a sense to advance the material in the direction indicated by arrows Y, i.e., along the mine face 4, rearwardly along the front part of the side face 4a, to a higher level at the end turn 6b, and onto the receiving end of a suitable take-off scraper conveyor 7 which transports the material out of the excavation 1 or to coal wagons, not shown. The take-off conveyor 7 preferably comprises two chains. The prime mover 6b for the conveyor 6 preferably includes an electric motor; however, it is equally possible to employ a relatively slow hydrostatic drive or the like.

The frame 5 further carries a rearwardly and upwardly inclined ramp 8 which extends in front of the leg 5a and part 50 and along the outer side of the leg 5b. The purpose of this ramp is to act not unlike a shovel and to direct material which accumulates directly in front of and below the mine face 4 onto the conveyor 6 while the frame 5 is being shifted toward the mine face. Furthermore, and as will be described hereinafter, the teeth 20a of the material removing tool 20 of the cutter 14 act not unlike a feed screw and cooperate with the ramp 8 to deliver material onto the upper stringer of the conveyor 6.

The means for advancing the frame 5 stepwise toward the mine face 4 comprises two or more suitable hydraulic pit props 10 which rest on the mine floor 3 and can be extended to engage the mine roof 2, and double-acting advancing cylinders 9 which are articulately connected to the props 10 and to the longer leg 5a of the frame. In a manner which is known from the art of so-called walking mine room supports, the props 10 are extended before the frame 5 is to be advanced toward the mine face 4 so that their caps 10a firmly engage the roof 2 and their sole plates 10b engage the mine floor 3. The cylinders 9 are extended in the next step in the direction of the arrow X to advance the frame 5 toward the mine face 4; the props are then contracted to move the caps 10a away from the mine roof 2, and the cylinders 9 are contracted to advance the props 10 toward the mine face.

As best shown in FIG. 3, the sections 5A of the frame 5 define a centrally located channel or trough which accommodates the upper and lower stringers of the conveyor 6. The outer edge of the conveyor 6 is guided by the rear surface 11 of the ramp 8, and the inner edge of this conveyor is guided by the front or outer surface 12 of a multisection upright or bracket 13. The upper side of the inner edge of the conveyor 6 is guided by a plate-like cover member 8a which is welded to the topmost part of the ramp 8 and carries one guide rail 8b for the cutter 14. The other guide rail for the cutter 14 is constituted by the upper part of the bracket 13. The carriage 14A of the cutter 14 bridges the upper stringer of the conveyor 6 and is guided along the rail 8b and bracket 13 for lengthwise movement back and forth along the frame 5 between the free ends of the legs 5a and 5b. The carriage 14A is provided with two roller followers 15, 15a which respectively travel along the inner and outer sides of the bracket 13 so that the latter constitutes a positive guide for the cutter 14. A motion receiving projection or lug 16 of the carriage 14A extends downwardly at the outer side of the bracket 13 (inwardly of the guide rail 8b) and is connected to one link of an endless chain 17 which forms part of the drive for the cutter 14. The chain 17 is located in a horizontal plane and is trained around a first sprocket Wheel 18 installed in the frame 5 close to the free end of the leg 5a and around a second sprocket wheel (not shown) at the rear end of the leg 5b. The second sprocket wheel is rotatable in two directions by a hydrostatic motor 19 mounted on the leg 5b.

The tool 20 of the cutter 14 is a radial tool and comprises a single drumor roller-shaped body which is rotatable about a horizontal axis and is driven by a motor 1411 on the carriage 14A. The shaft 20b (see FIG. 1) of the tool 20 is mounted at the free end of an arm 21 which is secured to the carriage 14A by a pivot pin 22. A hydraulically operated double-acting cylinder unit 23 serves to pivot the arm 21 about the pin 22 and to thereby change the level of the tool 20 so that the latter can remove material along the mine face 4 and along the side face 4a in two or more passes. The material removing elements or teeth 20a of the tool 20 extend radially outwardly from the periphery of the tool. These teeth 20a are preferably arranged in a helical formation (see particularly FIG. 3) so that they automatically advance material toward the ramp 8 and onto the conveyor 6. The shaft 20b of the tool 20 is normal to the mine face 4 or to the side face 4a, depending on the momentary position of the cutter 14. The tool 20 is mounted at the foremost outer end of the carriage 14A and the latter is further provided with a plowshare-like loader 24 which is located directly behind the tool 20 and cooperates with teeth 20a to direct material onto the conveyor 6. The loader 24 comprises two mirror symmetrical portions one of which cooperates with the tool 20 and the other of which cooperates with a similar but stationary loader 25 mounted at the rear end of the leg 5b and serving to prevent displacement of removed material rearwardly and beyond the leg 5b when the cutter 14 travels toward the end position shown in FIG. 2. The motor 14a is an electric motor and drives the tool 20 through the intermediary of a suitable chain drive.

FIG. 2 illustrates the apparatus in a position its parts assume immediately after the cylinder 9 have completed shifting of the frame 5 and of the props 10 toward the mine face 4. The cutter 14 is located in its rear end position at the rear end of the shorter leg 5b and is ready to travel along the part 50, toward the free end of the leg 5a, and back to the end position shown in FIG. 2. The programing system of the apparatus comprises two

valves

26, 26a which can reverse the direction of the motor 19 for the chain 17 which advances the cutter 14. The valve 26 is provided at the rear end of the leg 5b and is tripped by a stud 14B on the carriage 14A when the cutter 14 reaches the end position of FIG. 2. When the cutter 14 reaches the other end position at the free end of the leg 51:, a second stud 14D on the carriage 14A trips the valve 26a which thereupon reverses the motor 19 in order to return the cutter to the position of FIG. 2 by reversing the direction of travel of the chain 17. The programming system preferably further includes suitable automatic starting means for the props 10 and cylinders 9 so that the frame 5 is advanced by a step in automatic response to return movement of the cutter 14 to the end position shown in FIG. 2. For example, the valve 26 can form part of a system of valves which automatically regulate the flow of a hydraulic medium in the props 10 and cylinders '9 when the stud 14B reaches the position of FIG. 2. Furthermore, the valve 26 and/or 26a may automatically admit a fluid medium to the cylinder 23 so that the latter can change the level of the tool 20 by pivoting the arm 21 about the pin 22 when the cutter 14 reaches the respective end position. For example, the valve 26a may initiate raising of the tool 2 0 whenever the cutter 14 reaches the free end of the leg 5a, and the valve 26 may initiate lowering of the tool. These valves can be replaced by solenoid valves or by plunger-type limit switches. All that counts is that the carriage 14A or another moving part of the apparatus can initiate a predetermined sequence of operations to move the cutter 14 back and forth, to advance the frame 5, and/or to change the cutting plane.

A very important advantage of the connecting part 50 between the legs 5a, 5b of the frame 5 is that it steers the cutter 14 in an arcuate path in which the teeth 20a of the tool 20 can remove suflicient quantities of material in the region at the junction of the faces 4 and 4a to permit unimpeded stepwise advance of the frame 5 and conveyor 6 when the cutter 14 reaches the end position of FIG. 2. Also, and since the tool 20 can travel all the way to or even along the shorter leg 5b, it removes material along the front end of the side face 40 to permit forward movement of the cutter 14 together with the frame 5. During travel from the leg 5a to the leg 5b or vice versa, the tool 20 forms a sickle-shaped cutout 4c at the lower end of the mine face 4 (as viewed in FIG. 2) which provides room for penetration of teeth 20a into the material of the mine face 4 when the tool 20 thereupon travels toward the free end of the leg 5a.

As stated before, the length of the shorter leg 5b need not exceed the length of the cutter 14 but it can be made longer even through such lengthening is not necessary at all because it suffices if the cutter 14 can be moved to an end position in which the axis of its tool 20 is normal to the side face 4a. This insures that the cutter 14 removes sufiicient amounts of material to facilitate a forward step in response to actuation of advancing cylinders 9. Of course, and since the tool 20 is located at the forward end of the carriage 14A, its teeth 20a remove sufiicient quantities of material at the upper end of the mine face 4 (as viewed in FIG. 2) to allow for unobstructed transport of the free end of the leg 5a.

When the cutter 14 leaves the end position of FIG. 2, the tool 20 removes an arcuate layer along the surface bounding the sickle-shaped cutout 4c and thereupon penetrates, without any period of transition, into the material along the mine face 4.

The novel design of the frame 5 is based on the recognition that, by properly selecting the path in which the tool 20 of the cutter 14 travels back and forth, the teeth 20a of the tool can remove material in such a way that a single tool will suffice to cut the frame free for stepwise advance toward the mine face 4 upon completed removal of a material layer from the mine face. A substantially L-shaped frame has been found to be ideally suited for such purposes because, at the free end of the leg 5a, the teeth 20a can ,cut free that extremity of the apparatus which is adjacent to the side face 4b and, when operatinga long the shorter leg 5b, the teeth 20a can remove sufficient quantities of material to provide room for forward movement of the respective extremity of the frame 5. Also, during travel along the concave surface bounding the cutout 4c, the teeth 20a remove enough material to permit penetration of the tool 20 into the mine face 4a without necessitating any axial movement of the tool relative to the frame 5, i.e., the tool need not be provided with a second set of teeth which would cut into the material along the mine face during axial movement of the tool, the same as mentioned in connection with the description of conventional coal mining apparatus with tools which rotate about horizontal axes. The teeth 20a of the tool 2 in the apparatus of the present invention are maintained in full material removing contact -with the seam during the major part of the operation, with the single exception of very short intervals required to shift the frame toward the mine face 4. The drive (motor 19) for the chain 17 and carriage 14A of the cutter 14 can be temporarily arrested when the cutter dwells in the end position of FIG. 2, i.e., during shifting of the frame 5 toward the mine face 4. The teeth 20a will remove material at the maximum rate as soon as the motor 19 is started again because they are immediately caused to penetrate into the material bounding the arcuate cut out 40. Since the tool 20 is installed at the foremost end of the carriage 14A, as seen in the direction of travel of the carriage from the end position of FIG. 2 toward the other end position, the teeth 20a can cut the frame free so that a single tool suffices to provide room at both extremities of the frame as well as to remove material during travel along the mine face. Removal of material need not be interrupted at all when the carriage 14A reaches the free end of the leg 5a and while the cylinder 23 causes the tool 20 to move to a different level prior to begin of a return stroke toward the end position of FIG. 2. In other words, a change in the level of the tool 20 necessitates no interruption in removal of material because the radially extending teeth 20a continue to bite into the mine face 4. As stated before, removal of material is interrupted very shortly only at the time when the cutter 14 returns to the end position of FIG. 2 and while the frame 5 is being shifted toward the mine face 4. Due to the fact that a single tool sufiices to remove material at both extremities of the frame 5 as well as along the mine face 4, the design of the cutter 14 is much simpler than in certain presently known mining apparatus with plural tools; moreover, the frame 5 can be shifted by resorting to a very simple and rugged advancing unit, such as that including the props and cylinders 9.

The conveyor 6 can be modified in a number of ways without departing from the spirit of the invention. Though it is presently preferred to use a so-called scraper conveyor with a single centrally located chain, conveyors with a single chain and with scrapers extending from one side of the chain can be used just as well. All that counts is to employ a conveyor which can be readily guided in an arcuate path, i.e., along the connecting part 50 of the frame 5. The conveyor 6 preferably consists of several separable sections so that its length may be changed if it becomes necessary to utilize the apparatus in excavations with longer or shorter mine faces. Thus, not only the parts 5a-5c but also the conveyor 6 may be assembled of separable components so that the length of the conveyor may be changed whenever it becomes necessary to change the length of the leg 5a.

The

valves

26, 26a which effect changes in the direction of travel of the cutter, stepwise transport of the frame 5, and/or changes in the level of the tool should be designed in such a way that their mechanims are properly protected against entry of dust, moisture or other foreign matter. The same applies if such valves are replaced by limit switches, solenoids or other suitable programming elements.

Finally, it is possible to employ two mining apparatus in tandem or to employ three or more such apparatus for removal of material in parallel underground excavations or in a single excavation of considerable width. If it becomes necessary to employ two apparatus, the shorter legs 5b of their frames are preferably placed side-by-side in the middle of the excavation. This will be readily understood by referring to FIG. 2 and by considering that the side face 4a is sufiiciently remote from the leg 5b to provide room for a second apparatus wherein the shorter leg of the frame is adjacent ot the leg 5b. However, it is equally possible to place a second or a third apparatus adjacent to the end turn 6a so that the free end of the longer leg in the frame of such apparatus is adjacent to the free end of the longer leg 5a shown in FIG. 2. Employment of four or more apparatus in a single excavation will necessitate placing additional frames next to the frames of the first three apparatus.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. Apparatus for mining coal or like materials in underground excavations bounded by a mine floor, a mine roof, a mine face and a side face, comprising a frame shiftable along the mine floor toward the mine face, said frame comprising a first part extending in parallelism with the mine face, a second part extending in parallelism with the side face adjacent to the mine face, and an arcuate third part connecting said first and second parts; a cutter arranged to travel along said first, third and second parts and vice versa and having a driven tool arranged to remove material along said faces and to form an arcuate cutout in front of said third part during said travel of the cutter; and conveyor means connected with said frame and arranged to transport material removed by said tool in a direction along said faces and thereupon away from said mine face.

2. Apparatus as defined in claim 1, wherein said frame is L-shaped and comprises a shorter leg constituted by said second part and a longer leg constituted by said first part.

3. Apparatus as defined in claim 1, wherein the length of said second part approximates the length of said cutter.

4. Apparatus as defined in claim 1, wherein said frame comprises at least one guide rail extending along said parts thereof, said cutter comprising a carriage which tracks said rail.

5. Apparatus as defined in claim 4, wherein said frame comprises two parallel guide rails and said carriage extends above and across said rails, said rails defining between themselves a channel for said conveyor means.

6. Apparatus as defined in claim 1, wherein said conveyor means comprises an endless conveyor having a first end turn at that end of said first part which is remote from said third part and a second end turn at that end of said second part which is remote from said third part.

7. Apparatus as defined in claim 6, wherein said second end turn is raised above the mine floor and is arranged to discharge the material, and further comprising take-olf conveyor means arranged to receive material from said raised second end turn.

8. Apparatus as defined in claim 1, wherein said frame further comprises an inclined ramp extending in front of said first and third parts and between said second part and said side face to guide the material removed by said tool onto said conveyor means in response to shifting of said frame toward the mine face.

9. Apparatus as defined in claim 1, further comprising advancing means for shifting said frame stepwise toward the mine face upon removal of a layer of material from said faces and along said cutout.

10. Apparatus as defined in claim 9, wherein said advancing means comprises extensible and contractible pit props operating between said mine roof and said mine floor, and advancing cylinders connected between said props and said first part of said frame.

11. Apparatus as defined in claim 10, wherein said pit props are hydraulically operated and wherein said advancing cylinders are of the double-acting hydraulic yp 12. Apparatus as defined in claim 1, wherein said cutter comprises a carriage movably supported by said frame, an arm connected to said carriage for pivotal movement about a horizontal axis, and means for pivoting said arm, said tool being mounted on said arm at a point remote from said axis and being rotatable with reference to said arm about a second horizontal axis.

13. Apparatus as defined in claim 12, wherein said tool resembles a drum and is provided with radially extending material removing elements.

14. Apparatus as defined in claim 13, wherein said second axis is respectively normal to said mine face and said side face when the cutter respectively travels along the first and second parts of said frame.

15. Apparatus as defined in claim 13, wherein said material removing elements are arranged in helical formation so that they constitute a feed screw which advances material removed from said faces toward said conveyor means.

16. Apparatus as defined in claim 15, wherein said carriage is provided with loader means cooperating with said material removing elements to enhance the transfer of said removed material onto said conveyor means.

17. Apparatus as defined in claim 1, wherein said parts of said frame consist of shorter sections connected to each other end-to-e-nd, said sections being separable from each other.

18. Apparatus as defined in claim 17, wherein said conveyor means comprises a plurality of separable sections.

19. Apparatus as defined in claim 1, further comprising drive means for advancing the cutter along said parts of said frame.

20. Apparatus as defined in claim 19, wherein said drive means comprises an endless chain and said cutter comprises a carriage connected with a portion of said chain.

21. Apparatus as defined in claim 20, wherein said chain is disposed in a horizontal plane and said drive means further comprises sprocket wheels carried by said frame and motor means driving one of said sprocket wheels, said chain bein trained around said sprocket wheels.

22. Apparatus as defined in claim 1, further comprising programming means for reversing the direction of said cutter after the cutter respectively reaches that end of said first part which is remote from said third part and that end of said second part which is remote from said third part.

23. Apparatus as defined in claim 22, wherein said cutter has a tool movable between a plurality of levels intermediate said mine roof and said mine floor and wherein said programming means comprises means for changing the level of said tool simultaneously with a reversal in the direction of travel of said cutter.

24. Apparatus as defined in claim 1, further comprising advancing means operative to shift said frame toward the mine face, and means for operating said advancing means when said cutter reaches the second part of said frame.

25. Apparatus as defined in claim 1, wherein said conveyor means comprises a scraper flight conveyor with a single endless chain.

References Cited UNITED STATES PATENTS 1,864,785 6/1932 Wilhelmi 299 2,935,310 5/ 1960 Davies 29943 FOREIGN PATENTS 1,400,211 4/1965 France. 1,144,217 2/1963 Germany.

717,593 10/1954 Great Britain. 1,005,490 9/1965 Great Britain.

ERNEST R. PURSER, Primary Examiner.

US. Cl. X.R. 299-19, 31, 45