US3785704A

US3785704A - Planer mining installation

Info

Publication number: US3785704A
Application number: US00244168A
Authority: US
Inventors: C Rassmann; B Ostrop; A Hauschopp
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1971-04-17
Filing date: 1972-04-14
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15
Also published as: ZA722548B; FR2133570B1; GB1384592A; DE2118713B2; DE2118713A1; JPS5428803B1; DE2118713C3; FR2133570A1; CS183657B2

Abstract

A mineral mining installation composed of a plough movable along a multi-section conveyor. The plough is constructed from an elongate beam supported in parallelism with and above the mineral face side of the conveyor. The beam is supported at its ends by means of a combination of rigid columns and cutter bit carriers pivotably attached to the beam. The cutter bit carriers engage a guide rail at the mineral face side of the conveyor and the columns are in turn supported on the carriers. The beam and carriers form a parallelogram-type linkage with the guide rail and the carriers pivot to a limited extent as the plough is moved along the conveyor. A further support means extends from the beam over the conveyor and is guided at the goaf side of the conveyor where a drive chain is provided. Sets of cutter bits are attached to the columns and the beam as well as to the cutter bit carriers.

Description

United States Patent [191 Ostrop et al.

' PLANER MINING INSTALLATION [75] Inventors? Berthold Ostrop, Selm; Christoph Rassmann, Lunen; Alois Hauscliopp, Werne an der Lippe, all of Germany [73] Assignee: Gewerkschaft Eisenhutte Westfalia,

Westfalia, Germany [22] Filed: Apr. 14, 1972 [21] Appl. No.: 244,168

[30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 1,103,765 2/1968 Great Britain 299/34 [4 1 Jan. 15, 1974 Primary Examiner-Ernst R. Purser Attorney-Richard C. Sughrue et al.

[57] ABSTRACT A mineral mining installation composed of a plough movable along a multi-section conveyor. The plough is constructed from an elongate beam supported in parallelism with and above the mineral face side of the conveyor. The beam is supported at its ends by means of a combination of rigid columns and cutter bit carriers pivotably attached to the beam. The cutter bit carriers engage a guide rail at the mineral face side of the conveyor and the columns are in turn supported on the carriers. The beam and carriers form a parallelogram-type linkage with the guide rail and the carriers pivot to a limited extent as the plough is moved along the conveyor. A further support means extends from the beam over the conveyor and is guided at the goaf side of the conveyor where a drive chain is provided. Sets of cutter bits are attached to the columns and the beam as well as to the cutter bit carriers.

21 Claims, 4 Drawing Figures PATENTEU JAN 1 5'31,

SHEET 2 OF 3 lPLANER MINING INSTALLATION BACKGROUND TO THE INVENTION The present invention relates to a mineral mining installation.

In mining, various forms of mineral winning appliances or ploughs are known which are moved back and forth along a conveyor. Usually such ploughs have a 'main body provided with sets of cutter bits directed SUMMARY OF THE INVENTION According to the inventionthere is provided a mineral mining installation comprising amineral winning appliance adapted for movement along a conveyor, the appliance being composed of an elongate member disposed generally parallel to the longitudinal axis of the conveyor and in a position vertically offset from the conveyor and means for supporting the elongate member so that a space is formed between said support means, the conveyor and the elongate member with the elongate member and the support means effectively forming a parallelogram-type linkage.

The winning appliance or v plough is preferably adapted for use with longwall mineral seams with a thickness from 1.3 to 2.5'metres.

The aforesaid supportmeans preferably supports the elongate member at the mineral face side of the conveyor and includes cutter bit carriers pivotable in relation to said elongate members. Stop members can be provided to limit the pivoting of the carriers. The support means preferably also comprises upstanding columns rigidly connected to the ends of the elongate member. It is particularly significant that the appliance is supported by pivotable carriers and that the engagement and disengagement of the cutter bits can be controlled by the pivotal movement of the carriers effected when the appliance reverses its direction of movement. The columns can be provided with cut-limiting devices.

According to a further feature of the invention there is provided additional support means for supporting the elongate member at the goaf side of the conveyor. This additional support means preferably comprises a plate attached to said elongate member and extending over the conveyor and a support member connected to the drive chain and guided at the goaf side of the conveyor, the support member being pivotably connected to the plate.

The cutter bit carriers can have lower portions which extend downwardly over the mineral face side of the conveyor with clearance therefrom to project towards the floor of the mine working. The sets of cutter bits provided on the lower portions of the carriers face out wardly from the appliance and the portions preferably have inclined loading faces directed inwardly of the appliance.

Sets of cutter bits are preferably pivotably connected to the columns in such manner that only the cutter bits attached to the rearmost column relative to the direction of movement of the appliance are effective in cutting the mineral face.

A drive chain for propelling the appliance along the conveyor is conveniently provided at the goaf side of the conveyor and the support member of the additional support means can be connected to the chain. It is desirable for the plate of the additional support means to be connectible to the central region of the elongate member at various vertically offset positions.

Preferably the lower portions of the carriers engage a guide rail disposed at the mineral face side of the conveyor. Sliding skids and/or rollers can be provided between the guide rail and the carriers. The columns can likewise engage the lower portions of the carriers. During operation the carriers tend to pivot in relation to the elongate member as a result of the frictional force between the carrier and the guide rail and the reactive forces produced by the cutting action of the appliance. This pivotal movement of the carriers occurs in the manner of a parallelogram-type linkage. Preferably the lower portions of each of the carriers engages the guide rail over a first bearing surface and the lower end of the associated column engages the lower portion of the carriers over a second bearing surface, the first and second bearing surfaces lying on a common circle concentric with the axis of pivotal movement of the carrier. Additional sets of cutter bits can be pivotably attached to the ends of the elongate member in such 7 manner that only the set of cutter bits at the forward end of the elongate member relative to the direction of movement of the appliance is effective in cutting the mineral face.

The cutter bits attached to the columns preferably effect a deeper cut than the other cutters so as to produce a preliminary cut at about the centre of the mineral seam. This cut terminates at some distance from the longwall when the appliance is reversing its direction of motion but the sets of cutter bits on the column nearest the end of the longwall become effective when the appliance is moved back to remove the mineral left by the preliminary cut. These newly-effective cutter bits then serve to produce a preliminary cut for the next cutting cycle. In this way stable zones at the ends of the longwall become unnecessary.

A further advantage of the invention can be realized by making the point of attack of the chain on the appliance longitudinally adjustable, so that the appliance is able, at least over part of its length, to overrun the chain reversal point. This characteristic of the invention is based on the realization that with an appliance of relatively great length it is less advantageous to utilize the so-called tearing hook effect, which is usually obtained by giving the chain a point of attack in advance of the cutter bits. An automatic displacement device can be provided to move the support member to a limited extent so that the appliance is moved on when the drive chain cannot effect any further movement of the appliance at one end of the longwall.

According to a further feature of the invention, the cutting contour effected at the floor zone of the seam by the set of bits provided on pivotable carriers is inclined in res pect of the mineral face in such a way that the mineral face and the conveyor side wall or the guide rail provided on the latter converge V-wise towards the floor. In this way an acute-angle gap is formed so that, during the pivoting operation which the carriers perform in a vertical plane parallel to the mineral face, the cutter bits provided on one of the carriers can disengage from the mineral face prior to a fresh cutting cycle. The lower portion of each carrier is preferably of wedge-shaped configuration, the width of its end face nearer to the floor being largely equal to that of the cutting surface of the lowermost cutter bits. It is advisable for at least one of the two floor cutter bits to be vertically displaceable in relation to the carrier, and these bits are preferably extensible and retractable by hydraulic means. Guide means which is preferably Cardanic, can be associated with these displaceable floor bits and this guide means can be constructed in such a way that by angular movements in a vertical plane parallel to the mineral face the cutting angle towards the floor is adjustable, while by pivoting movements in a likewise vertical plane, which is nevertheless perpendicular to the mineral face, the angle of the floor bits towards the floor is adjustable. In addition, by a vertical longitudinal displacement of the bits, the cutting depth in respect of the floor can be adjusted.

The aforesaid guide rail with which the carriers are in engagement may be L-shaped with a top wall projecting over the upper flange of the conveyor to form a groove which is open towards the conveyor. The carriers can have hook-shaped projections which are received in the groove, with a certain amount of clearance, in such a way that when the conveyor and the appliance are in the normal position the projections do not come to rest against any surface. On the goat side of the installation guide channels for the chain can be provided. An upper channel can accommodate the traction run of the chain and a lower channel can accommodate the return run in the manner known per se. These channels are preferably so positioned in relation to one another that they align with the take'up-point and the run-off point of the chain on the reversing wheels.

The appliance can be exceptionally heavy and designed in particular for cutting through the entire thickness of a mineral seam with most of the tractive force acting on the appliance can be converted into cutting work. The appliance of the invention only requires a very narrow passage, as the parts extending beyond the mineral face of the conveyor can be made relatively short.

The point of attack for the chain, on the one hand, and the resulting over-all cutting-power of the bits on the mineral face, on the other, are situated opposite each other, at approximately the same level, and thus turning forces can be equalized. The point of attack can moreover be positioned approximately in the centre of gravity for the over-all mass of the appliance and this ensures very smooth operation of the appliance.

The guide parts of the drive chain are preferably so arranged that when the conveyor is moved forwards no fine coal can find its way into thepath of the chain and particularly, of course, into the return run. This enables the chain to be lubricated, hitherto impossible in mining, owing to the serious fouling of the tracks, and the chain guiding system can be made of materials which produce little noise. This in turn means that the chain speeds can be increased without exceeding the permis sible noise level. Furthermore, it is now possible to incorporate in the drive run of the chain travel limiting devices and control switches which would not be possible in the guide channels contaminated by dirt and extraneous matter. The provision of these control switches, in its turn, enables the entire installation to be automated.

The invention may be understood more readily and various other features of the invention may become more apparent from consideration of the following description.

BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of part of a mineral mining installation made in accordance with the invention;

DESCRIPTION OF PREFERRED EMBODIMENTS Referring initially to FIGS. 1 to 3, there is shown a mineral mining installation which has a winning appliance or plough 1 guided for movement along a multisection conveyor l9. The conveyor 19 is, in known manner, constructed from channel sections joined endto-end, each channel section being composed of two generally sigma-shaped side walls adjoined by a horizontal wall forming a conveying surface. A scraper chain assembly serves to transport mineral along the conveyor 19. The plough 1 has an elongate member in the form of a rigid beam 6 extending parallel to the longitudinal axis of the conveyor 19 and supported on (inter alia)

vertical columns

4, 5. The

columns

4, 5 are indirectly supported for movement along an L-shaped guide rail 3 connected to the mineral-face side wall 2 of the conveyor 19. As shown, the rail 3 has a top bearing wall 29 which projects over the upper flange of the side wall 2.

The space defined between the guide rail 3, the beam 6 and the columns 4, S has a length at least equal to one of the channel sections of the conveyor ,19.

The plough l is provided with

cutter bit carriers

9, 10 disposed at ends of the beam 6 adjacent the

columns

4, 5. The

carriers

9,10 also support the beam 6 and the

carriers

9,10 are pivotable to a limited extent about spindles 8 carried by the beam 6 and extending generally perpendicularly to the mineral face denoted 7. As shown in FIG. 1, the cutter bit carriers 9, l0 slidably engage the top wall 29 of the guide rail 3.

There is provided additional support means in the form of a shaped plate 11 connected to a verticallydeepened central region 40 of the beam 6 and projecting rearwardly from the face 7 and over the conveyor 19. The central region 40 of the beam 6 is provided with two pairs of apertures 41 each pair of apertures 41 being disposed one above another. The plate 11 has corresponding projections or plugs 42 which fitinto the upper or lower sets of apertures 41. The beam 6 is also provided with bores which extend downwardly from the uppermost edge thereof to penetrate the apertures 41. The plugs 42 of the plate II are also provided with bores extending vertically downwards so that the plugs 42 can be inserted into one or other set of apertures 4i and secured therein with pins 44 received by the aligned bores in the beam 6 and the plugs 42. The plate II can thus be secured to the beam 6 in one of two selectible positions. The plate Ill which has a somewhat vaulted-shaped cross-section parallel to the conveyor is hinged, by means of a shaft 29, to a downwardlyextending support member I2 guided at the stowage or goaf side of. the installation. The shaft Ztl extends substantially parallel to the longitudinal axis of the conveyor I9. The support member I2 is provided with a guide element 21 at its lower extremity and this element 2ll engages in the upper channel 23 of three channels provided by a profiled plate member 50 attached to the goat side wall of the conveyor I9. The upper and

lower channels

23, 24 respectively, of the profiled plate 50 receive a drive chain 22 which is guided for movement within the

channels

23, 24. The guide element 21, which is received in the channel 23, is connected to the chain 22 so as to effect movement of the plough 1 along the conveyor I9 when the chain 22 is driven. A further guard plate 5i. is disposed at the outer side of the

channels

23, 24 and the chain 22.

It may be convenient at this stage to refer to the modified construction depicted in FIG. 4 where for convenience like reference numerals denote like parts to the construction of FIGS. I to 3. In contrast to the beam 6 of the FIG. I construction, the plough ll of FIG. 4 has a composite structure constituting the elongate member. This structure is composed of a central holder 62 which serves to receive

end parts

60, 61 each of which is resiliently torsionable about the longitudinal axis of the holder 62. The end parts 69, 61 are clamped within the holder 62.

Referring now collectively to FIGS. I to 4, the cutter bit carriers 9, M) are each essentially composed of three portions. More particularly, each carrier 9, I9 has a lower portion, which bears a set of cutter bits, I3, I4, an intermediate portion and an upper portion. The lower portions of the carriers 9, III are each of an irregular hexagonal shape in side view and triangular shape in end view. These lower portions each have a hooklike projection which extends over the top wall 29 of the rail 3 and has an extremity received in a channel 5ll formed between the underside of the wall 29 and the upper face of the upper flange of the conveyor side wall 2. There is sufficient clearance horizontally and vertically, as designated by the

numerals

52, 53 in FIG. 4, to enable the projection of each lower portion of the carriers 9, III to cope with any unevenness of the floor of the working even when the plough I is relatively long. Between the projection and the main forward body of each lower portion of the carriers 9, It there is a recess which has a curved surface 28 which seats on the top wall 29 of the guide rail 3. The lower portions of the carriers 9, I also each have a curved surface 27 which extends beneath and abuts the lower ends of the associated column 4, The surfaces 27, 2 9

of each lower carrier portion lie on a common circle 3. Rollers or the like can also be provided at one or both the

surfaces

27, 28.

The intermediate portions of the carriers 9, I0 project upwardly behind the

columns

4, 5 relative to the mineral face 7. The upper portions of the carriers 9, It) are formed as projections 25 which engage adjustable stop members 26 provided on the elongate members 6, (FIGS. I-3) or -62 (FIG. 4).

The cutter bits I3, I4 are disposed to face towards the ends of the plough I and the inclined inner sides of the lower portions of the carriers 9, I9 act as loading faces. This arrangement provides a cutting contour of V-shaped configuration converging towards the floor of the working, and the engagement and disengagement of the cutter bits I3, I4 with the face 7 is controlled by the movement of the carriers 9, Id. The overall arrangement of the elongate member 6, 60-62 and the carriers 9, I0 provide a parallelogram-type linkage whereby during operation displacement of the

carriers

9, 10 produced as a result of the frictional force encountered between the rail 3 and the carriers 9, It) and as a reaction to cutting friction experienced by the cutter bits 13, I4, occurs.

Two further sets of cutter bits I5, I6 are pivotably connected with hinges pivotable about axes 30 to the inner sides of the

columns

4, 5. Stop members 3I, 32 are attached to the bits I5, I6 and disposed between the cutter bits I5, I6 and the

respective columns

4, 5. As shown in FIG. 2, during operation the rearmost set of cutter bits 14, IS in relation to the direction of movement of the'plough I is moved outwardly by engagement with the mineral face 7 to become rigidly held in a cutting position by the associated

stop membet

31, 32. The foremost set of cutter bits I3, 14, relative to the direction of movement of the plough I, is in contrast moved inwardly by engagement with the face 7 to an inoperative position.

Upper sets of cutter bits I7, I8 are similarly pivotably connected with hinges pivotable about axes 35 to the ends of the elongate member b, oil-62.

Stop members 90, 9i are attached to the cutter bits I7, 18 and disposed between the cutter bits I7, I8 and the elongate member 6, 60-62. As shown in FIG. 2,

,during operation, the foremost set of cutter bits I7, 18

in relation to the direction of movement of the plough I is moved outwardly by its engagement with the face 7 to become rigidly held in a cutting position by virtue of the stop member 99, 91 thereof. The rearmost set of cutter bits I8, I7 relative to the direction of the plough movement is moved inwardly to an inoperative position by its engagement with the face 7. The

cutter bits

15, 16 are designed to cut more deeply than the cutter bits 13, I4, 17, I8 so at the central region of the face 7 a preliminary cut is made which loosens the mineral and makes the cutting of the mineral from the upper and lower regions of the face 7 more easy. Devices 34 which limit the overall depth of cut produced by the plough I and more particularly by the sets of cutter bits 13, I4, 17, I8, are provided on the mineral face side of the

columns

4, 5 These devices 34 have detachable wear plates 33.

Since the arrangement composed of the support member I2 and the plate II is attached to the central region of the beam 6 the point of attack of the chain 22 is centralized and tends to follow up the foremost sets of cutter bits I3, I4, 17, I8 and precedes the sets of cutter bits I5, I6 so that these latter cutting tools effeet a tearing hook action on the mineral face 7 which produce a cut which is effective as a preliminary cut for the succeeding cutting cycle. in addition, the centralized point of attack and the length of the plough l ensures that the plough 1 can travel to the end of a longwall face. No stable hole is required since the reversal zone for the chain 22 and the end of the longwall face are generally closer together than the distance between the point of attack and each of the

cutter bit carriers

9, 10. v The operation of the plough installations described above is as follows: Tractive force applied to the chain 22 is transmitted via the

assembly

11, 12 to the elongate member 6, 60-62, and thence to the

carriers

9, 10 to move the plough 1 in one direction along the conveyor 19. Since the majority of the weight of the plough 1 is transmitted to the guide rail 3 from the

carriers

9, 10, frictional forces occur between the lower portions of the latter and the guide rail 3. These forces in conjunction with the cutting resistance encountered by the foremost set of

cutter bits

13, 14 engaging the mineral face 7 cause the associated foremost carriers 9, l topivot about the spindle 8 and assume an inclined position in relation to the beam 6, 60-62, as limited by the stop member 26. The rearmost set of cutter bits l4, 13 is, in contrast, inoperate for cutting and the associated rearmost carrierll), 9 pivots in the same sense as the

formost carriers

9, 10 so that the loading face of the

carrier

10, 9 is directed towards the floor to cause detached mineral to be loaded in the conveyor 19. As described hereinbefore, the sets of bits l7, 18 facing forwardly of ,-the direction of movement of the plough l is brought into a cutting position set by the stop member 90. 91 f and the set of

bits

15, 16 which is located rearwardly j' of the direction of movement of the plough l is brought into a cutting position set by the

stop member

31, 32. j. The set of cutter bits l5, l6 serve to produce a prelimil nary cut prior to the reversal of the direction of movement of the plough 1, i.e., in. the preceding cutting I cycle to that for which it is effective. When the plough 1 reaches the end of the longwall the tractive force is applied to the chain in a reverse direction to hitherto with the result that the plough 1 moves back along the l face 7. In this case the carriers 9, l0 pivot in an oppol site sense to that hitherto produced and the setof cutmember and means for supporting the member in a position generally disposed parallel to and vertically above the conveyor, said support means including spaced-apart cutter bit carriers which are pivotably connected to said elongate member to provide a space between the support means and the elongate member.

3. An installation according to claim 2, wherein said support means supports the elongate member at the mineral face side of the conveyor.

4. An installation according to claim 2, wherein there is provided additional support means for supporting the elongate member at the goaf side of the conveyor.

5. An installation according to claim 4, wherein a drive chain is provided on the goaf side of the installation for moving the appliance along the conveyor and said additional support means is connected to said drive chain.

6. An installation according to claim 5, wherein the additional support means comprises a plate attached to l ter

bits

13, 14 formerly employed for cutting, move away from the face and the now-forwardly directed cutter bits l4, [3 become operative for cutting. Similarly the sets of

cutter bits

15, 16 and l7, l8 pivot and reverse their roles so that the now forwardly directed

cutter bits

17, 18 and the now rea rwardly located

cutter bits

15, 16 are operative for cutting. The cut produced by the set of cutter bits l5, l6 terminates some distance from the .end of the longwall but when the plough movement is reversed the set of

bits

15, 16 forj merly inoperative serve to cut the mineral left by the E l l ance comprises:

said elongate member and extending over the conveyor and a support member connected to the drive chain and guided at the goaf side of the conveyor, the support member being pivotably connected to the plate.

7. An installation according to claim 6, wherein the plate of the additional support means is attachable to a central region of the elongate member in one of several pre-determined vertically offset positions.

8. An installation according to claim 2, wherein there ,is provided stop members to limit the pivotal movement of the carriers. I

9. An installation according to claim 2, wherein the support means also comprises upstanding columns rigidly connected to the ends of the elongate member.

10. An installation according to claim 9, wherein the lower ends of the columns are in frictional engagement with the cutter bit carriers.

11. An installation according to claim 10, wherein sets of cutter bits are pivotably attached to the columns in such manner that only the cutter bits attached to the rearmost column relative to the direction of movement of the appliance are effective in cutting the mineral face.

12. An installation according to claim 11, wherein additional sets of cutter bits are pivotably attached to the ends of the elongate member in such manner that only the set of cutter bits at the forward end of the elongate member relative to the direction of movement of the appliance is effective in cu tting the mineral face.

l3.'An installation according to claim 12, wherein the stop members are provided for the sets of cutter bits attached to the columns and to the elongate member.

the lower portions of thec agiers project utwa 14. An installation according to claim 10, wherein the carriers are slidably guided on a guide rail attached to the mineral face side of the conveyor and during operation the carriers tend to pivot in relation to the elongate member as a result of the frictional force between the carriers and the guide rail and the reactive forces produced by the cutting action of the appliance.

15. Aninstallation according to claim 14, wherein the lower portions of each of the carriers engages the guide rail over a first bearing surface and the lower end of the associated column engages the lower portion of the carrier over a second bearing surface, the first and second bearing surfaces lying on a common circle concentric with the axis of pivotal movement of the carrier.

16. An installation according to claim 2, wherein the cutter bit carriers are disposed at the ends of the elongate member, said carriers each having a lower portion which extends over the mineral face side of the conveyor to face towards the floor of the working, cutter bits being attached to said lower portion so as to face outwardly from the elongate member and each carrier also has an upper projected portion engageable with a stop member to limit the pivoting movement of the carrier.

17. An installation according to claim 16, wherein rdly beyond the columns relative to the mineral fac e and the columns are provided wtih devices for limiting the depth of cut of the appliance.

18. An installation according to claim 2, wherein the carriers are slidably guided on a guide rail attached to the mineral face side of the conveyor and during operation the carriers tend to pivot in relation to the elongate member as a result of the frictional force between the carriers and the guide rail and the reactive forces produced by the cutting action of the appliance.

19. An installation according to claim 18, wherein the guide rail is L-shaped with a top wall extending over the mineral face side wall of the conveyor so that a groove is formed between the top wall and the upper flange of the conveyor side wall, the lower portions of the carriers each being formed with a hook-like projection which freely engages in said groove with a degree of clearance sufficient to preclude jamming.

20. An installation according to claim 2, wherein the lower portions of the carriers have inwardly directed inclined faces which serve as loading faces for transferring detached mineral into the conveyor.

21. An installation according to claim 2, wherein the conveyor is composed of channel sections joined endto-end and the space between the carriers has a length equal to or greater than the length of one of the con-

Claims

1. In a mineral mining installation comprising in combination: a conveyor and a mineral winning appliance guided for movement along guide means on said conveyor, the improvement wherein said mineral winning appliance comprises: an elongated member disposed generally parallel to said conveyor and support members supporting said elongated member vertically above said conveyor, said support members being spaced apart to provide a space between said support members and said elongated member, being pivoted to said elongated member, and being in sliding engagement with the guide means on said conveyor, whereby said support members and said elongated member effectively constitute a parallelogram-type linkage.

2. A mineral mining installation comprising a conveyor, a mineral winning appliance guided on the conveyor, the appliance being composed of an elongate member and means for supporting the member in a position generally disposed parallel to and vertically above the conveyor, said support means including spaced-apart cutter bit carriers which are pivotably connected to said elongate member to provide a space between the support means and the elongate member.

6. An installation according to claim 5, wherein the additional support means comprises a plate attached to said elongate member and extending over the conveyor and a support member connected to the drive chain and guided at the goaf side of the conveyor, the support member being pivotably connected to the plate.

8. An installation according to claim 2, wherein there is provided stop members to limit the pivotal movement of the carriers.

12. An installation according to claim 11, wherein additional sets of cutter bits are pivotably attached to the ends of the elongate member in such manneR that only the set of cutter bits at the forward end of the elongate member relative to the direction of movement of the appliance is effective in cutting the mineral face.

13. An installation according to claim 12, wherein the stop members are provided for the sets of cutter bits attached to the columns and to the elongate member.

14. An installation according to claim 10, wherein the carriers are slidably guided on a guide rail attached to the mineral face side of the conveyor and during operation the carriers tend to pivot in relation to the elongate member as a result of the frictional force between the carriers and the guide rail and the reactive forces produced by the cutting action of the appliance.

15. An installation according to claim 14, wherein the lower portions of each of the carriers engages the guide rail over a first bearing surface and the lower end of the associated column engages the lower portion of the carrier over a second bearing surface, the first and second bearing surfaces lying on a common circle concentric with the axis of pivotal movement of the carrier.

17. An installation according to claim 16, wherein the lower portions of the carriers project outwardly beyond the columns relative to the mineral face and the columns are provided wtih devices for limiting the depth of cut of the appliance.

21. An installation according to claim 2, wherein the conveyor is composed of channel sections joined end-to-end and the space between the carriers has a length equal to or greater than the length of one of the conveyor channel sections.