US3276819A

US3276819A - Backing arrangement

Info

Publication number: US3276819A
Authority: US
Publication date: 1966-10-04
Anticipated expiration: 1983-10-04

Description

tive bights extending oppositely to one another in directions from the center of the chair frame toward opposite sides of the latter and with said leg portions of each of said frame members diverging from one another foreand-aft of the chair frame; a resilient back and under-seat frame structure comprising a rear upstanding part and two laterally spaced portions extending forwardly from the bottom of said rear upstanding part and each crossing the two side portions of respective ones of said bights; and second means securing said laterally spaced portions to said bight side portions where said laterally spaced portions cross said bight side portions, the securing by said first means at said single location and the securing by said second means providing the only securing of said resilient leg and under-seat frame members and said resilient back and under-seat frame structure together, whereby said chair frame is resilient, enabling load thereon to be distributed evenly through all four leg portions to a floor.

2. A chair frame construction according to claim 1 in which said second securing means includes spacers interposed between and connecting each of said laterally spaced portions and one of the side portions of the respective bights.

3. A chair frame construction according to claim 2 in which said spacers are respectively interposed between said laterally spaced portions of said back and under-seat frame structure and the two foremost side portions of said leg and under-seat frame member bights.

4. A chair frame construction according to claim 3 in which each of said spacers comprises a U-shaped membed having two spacer legs and a connecting part, said connecting part being dished to form a seat for the associ-ated forwardly extending portion of said back and under-seat frame structure, and the spacer legs of each of said spacers being dished transversely to the dishing of said connecting part to form seats for receiving the associated side portion of one of said leg and under-seat frame members.

51 A chair frame construction according to claim 1 in which said combination leg and under-seat frame members and said back and under-seat frame structure are metallic, and in which said securing means comprises welds.

6. A chair frame construction according to claim 1 in which said back and under-seat frame structure comprises a unitary elongated element including an inverted V- shaped part constituting said upstanding part, said two laterally spaced portions respectively extending forwardly from the bottoms of opposite sides of said V-shaped part.

7. A chair frame construction according to claim 1 in which said bights are inclined from the center of the chair frame towards the opposite sides thereof.

8. A chair frame construction according to claim 1 in which said bights are inclined downwardly from the center of the chair frame towards the opposite sides thereof.

9. In a chair, a frame including two unitary combination leg and under-seat frame members, each comprising an elongated resilient element having intermediate its ends a bight including a central connecting portion and two side portions spaced from each other fore-and-aft of the frame and extending from opposite ends of said central connecting portion, said side portions terminating in continuing downwardly extending mutually divergent leg portions; first means securing the central connecting portions of the bights of said two combination leg and under-seat frame members together at a single location at the center of said chair frame with the side portions of the respective bights extending oppositely to one another in directions from the center of the chair frame toward opposite sides of the latter and with said leg portions of each of said frame members diverging from one another fore-and-aft of the chair frame; a resilient back and underseat frame structure comprising a rear upstanding part and two laterally spaced portions extending forwardly from the bottom of said rear upstanding part and each crossing above the two side portions of respective ones of said bights; second means securing said laterally spaced portions to said bight side portions where said laterally spaced portions cross said bight side portions, the securing by said first means at said single location and the securing by said second means providing the only securing of said resilient leg and under-seat frame members and said resilient back and under-seat frame structure together, whereby said chair frame is resilient, enabling load thereon to be distributed evenly through all four leg portions to a floor; :a back panel secured to said rear upstanding part of said back and under-seat frame struc ture; and a seat p'anel secured on top of and to said forwardly extending portions of said back and underseat frame structure.

10. A chair frame construction according to claim 9 in which said second securing means comprises spacers respectively interposed between and connecting each of said laterally spaced portions of said back and under-seat frame structure and the foremost of the side portions of the respective bights, and in which said seat panel is downwardly dished with its central portion being disposed substantially directly above the secured-together connecting portions of said bights, the side marginal edges of said seat panel being spaced above the junctures of said bight side portions and said downwardly extending mutually divergent leg portions.

11. A chair frame construction according to claim 10 in which said seat panel is yieldable.

12. A chair frame construction according to claim 10 in which said seat panel has a down-turned marginal edge, the portion of said edge extending across the back of the seat panel passing over said laterally spaced forwardly extending portions of said back and under-seat frame structure and being supportable thereby.

13. A chair frame construction according to claim 10 in which said seat panel is concave on its bottom adjacent its front and in which said back and under-seat frame structure is formed of a single piece of tubular material, said two laterally spaced, forwardly extending portions thereof terminating in front end parts which are closed and curved convexly on their upper surfaces to conform to the goncavity of the seat panel bottom adjacent the seat panel 'ront.

References Cited by the Examiner UNITED STATES PATENTS D. 161,177 12/1950 Harrison 297457 X 2,539,919 1/1951 Meek et a1 297451 2,815,801 12/1957 Fingerhut et a1. 297 -451 2,961,037 11/ 1960 Keefer 29745 1 3,000,669 9/ 1961 Silverman 29745 1 3,201,172 8/ 1965 Bliss 297445 FRANK B. SHERRY, Primary Examiner.

CASMIR A. NUNBERG, Examiner.

O t 4 A. LUBBE ETAL ,27 19 BACKING ARRANGEMENT Filed Sept. 6, 1963 INVENTORS ARM/IV 16535 W! HERBERT A'UTI'E/VB/MUCK United States Patent Oifice 3,276,819 Patented Oct. 4, 1966 3,276,819 BACKING ARRANGEMENT Armin Liibbe, Oberaden Post Kamen, and Herbert Hiittenbrauck, Billmerich, Kreis Unna, Germany, assignors to Gewerkschaft Eisenhute Westfalia, Wethmar, near Lunen, Westphalia, Germany, a corporation of Ger- Filed Sept. 6, 1963, Ser. No. 307,244 Claims priority, application Germany, Sept. 7, 1962,

9 Claims. ((11. 299-32 The present invention relates to a backing arrangement for lateral urging abutment against a mining conveyor adapted to extend longitudinally along a mine face to urge such conveyor toward the mine face, especially wherein such conveyor is provided with track means thereon upon which a planer is slidably mounted for back and forth movement of such planer while in extractive engagement with the mine face. More particularly, the present invention relates to such a backing arrangement, preferably hydraulically operated, in which a secondary or auxiliary urging means is provided linkably interconnected with the main urging means through an abutment bar, whereby such bar may be angularly displaced in a vertical plane for changing the resultant direction of force of the backing arrangement when placed against a mining conveyor with the abutment bar in urging contact with the side of the conveyor remote from the mine face.

Where minerals, such as coal, are mined or extracted by scraping methods, as for example using a planer guided on a conveyor for back and iorth movement along the mine face, the harder the mineral, for example coal, becomes the more diflicult it is to guide the planer consistently so that it cuts the coal or other mineral loose from the mine face precisely at the floor level of the mine. Of course, for the desired results to be achieved, the planer must not penetrate, or at least must not penetrate too deeply, into the mine floor, but neither should the planer be permitted to turn out of the coal face, ie be transversely displaced from the coal face, for instance, where the coal being extracted is so hard that the planer backs off.

It is an object of the present invention to overcome the foregoing drawbacks and to provide a backing arrangement for conveyors, especially where the conveyor is equipped with a planer guided for back and forth movement thereon, whereby the conveyor may be satisfactorily urged toward the mine face, with the conveyor and in turn the planer being maintained precisely at the desired level with respect to the mine floor.

Other and further objects of the invention will become apparent from a study of the within specification and accompanying drawing in which:

FIG. 1 is a schematic elevational view of a backing arrangement in accordance with one embodiment of the invention showing the backing arrangement in position against a longitudinally extending mining conveyor, and

FIG. 2 is a schematic elevational view, partially in section, of another embodiment of the backing arrangement in accordance with the present invention, also :shown adjacent a longitudinally extending mining convey-or.

It has been tound in accordance with the present invention that a backing arrangement of versatility and effectiveness may now be provided for lateral urging abutment against a mining conveyor adapted to extend longitudinally along a mine face to urge such conveyor toward the mine face, especially where the mining conveyor is equipped with track means for slidably mounting a planer thereon for back and forth movement of the planer while in extractive engagement with the mine face. The backing arrangement of the invention generally comprises base means for engaging the mine floor and mine ceiling, first urging means and second urging means operatively connected to the base means, each said urging means including a linearly displaceable urging member having a free end remote from said base means, the linear displaceable member of one of said urging means being operatively situated above the displaceable member of the other urging means, and an abutment bar disposed in a substantially vertical plane and pivotally connected by a separate pivot to each of said free ends to linkablywinterconnect said members at their free ends and to permit angular displacement of said bar in said vertical plane in response to linear displacement of at least one of said displaceable members. In this way, during abutment of the bar against the side of the conveyor remote from the mine face, the first and second urging means will urge the conveyor toward the mine face with a resultant direction of force which varies in dependence upon the angular disposition of the abutment .bar with respect to the mine floor.

Conveniently, the urging means in each instance may comprise a piston-cylinder arrangement including a piston part and a cylinder part, one of said parts being the corresponding linearly displaceable urging member and the other of said parts being operatively connected to the base means. The base means more specifically may include a supporting leg for engaging the mine floor 'and prop means mounted on said leg for engaging the "more effectively. Also, one of the piston-cylinder arrangements in this instance is pivotally connected by one of its parts to the supporting leg and by the other of its parts to the abutment bar. ,Resilient means are provided on the supporting leg in this connection tor normally downwardly urging such one piston-cylinder arrangementintermediate the pivotal connections thereof. Moreover, the other of the piston-cylinder arrange ments may be operatively connected to the base means via said other of the parts of said one piston-cylinder arrangement with one of the corresponding parts of said other piston-cylinder arrangement being fixed to said other of the parts of said one piston-cylinder arrangement and with the other of the corresponding parts of said other piston-cylinder arrangement being pivotally connected to the abutment bar.

In accordance with an alternate feature of the present invention, the prop means may take the form of a vertical prop mounted on the supporting leg for engaging the mine ceiling, with a carriage horizontally displaceably mounted on the supporting leg. In this instance, one of the piston cylinder arrangements may be pivotally connected by one of its parts to the supporting leg and by the other of its parts to the abutment bar, said other of its parts being also connected at least along a portion thereof to said carriage. Additionally, the other of said piston-cylinder arrangements may be operatively connected to the base means via said carriage with one of the corresponding parts of said other piston-cylinder arrangements being operatively connected to the carriage and with the other of the corresponding parts of said other piston-cylinder arrangements being pivotally connected to the abutment 3 1 bar.- More specifically, the supporting leg in this regard may be provided with an upper retaining means and a lower retaining means, said retaining means being vertically spaced apart, and the carriage may be provided in turn with an upper slide surface and a lower slide surface, such that a portion of the carriage is displaceably received within the supporting leg with a vertical clearance between the upper slide surface and the upper retaining means and with the lower slide surface in sliding engagement with the lower retaining means. Adjustable shim. means also may be provided effectively in the vertical clearance in question to limit adjustably the upward displacement of the carriage with respect to the supporting leg.

Advantageously, the other piston-cylinder arrangement may be further provided with a damping means operatively connected between said one of the corresponding parts of said other piston-cylinder arrangement and said carriage for absorbing excessive forces exerted on said other piston-cylinder arrangement during abutment of the bar against the conveyor.,

In accordance with one particular embodiment of the invention, hydraulically operated piston-cylinder means are provided in addition to the usual bracing pistoncylinder means, such that pressure components of various magnitude may be exerted on the mining conveyor and/ or planer guide means depending upon the extent to which the adjusting piston-cylinder arrangements are stressed to change the angle of the abutment bar with respect to its normal ,verticalposition. Thus, the resultant components of force may be exerted such that the over-all force is directed diagonally downwardly toward the mine floor or diagonally upward toward the mine ceiling, in addition to the normal horizontal direction toward the mine face, for overcoming an adverse position of the conveyor on the mine floor, so as to prevent the-conveyor from lift ing from its normal position or from digging undersirably downwardly into a soft area in the mine floor. By avoiding such possibilities, through suitable adjustment of the backing arrangement and in turn the planer guide and/ or conveyor, the planer will always be guided along its true longitudinal course, precisely along the horizontal level of the mine floor desired.

Referring to the drawing, in FIG. 1, a backing arrangement is shown in accordance with one embodiment of the invention, including a base means of U-shaped construction, with the free ends of the U downwardly facing,

a pit prop 11 being pivotally mounted by pivot 12 onto the supporting leg 10 at an angle with the mine floor sufficient to brace the base means against any displacement thereof in the direction toward the left as viewed in FIG. 1. A main piston-cylinder arrangement 13 including a piston 14 and a cylinder 15 is provided as well as a secondary piston-cylinder arrangement 16 including the secondary cylinder 17 and the secondary piston 18. The piston-cylinder arrangements 13 and 16 are connected linkably via the normally vertical abutment bar 19. More specifically, main piston 14 is pivotally connected by pivot 20 to supporting leg 10 and main cylinder 15 is pivotally connected to abutment bar 19-=by pivot 21, whereas secondary cylinder 17 is fixedly connected to the upper side 22 of main cylinder 15 while secondary piston 18 is pivotally connected by pivot 23 to abutment bar 19.

A longitudinally extending mining conveyor 27 of con ventional construction is shown having the side members 28 and 29 which are interconnected intermediate their height by trough plate 30. On side member 29 a suitable guiding track 31' in the form of a guiding tube is provided such that a planer of the usual type may be mounted thereon for movement back and forth along the mine face adjacent that side of the conveyor. In this connection, the conveyor in question may be of the usual double chain scraper conveyor type such as that shown in US. Patent 2,810,565, issued October .22, 1957, and US. Patent 2,990,168, issued June 27, 1961. Usually the coal or other mineral, extracted by the planer from the mine face is loaded onto the conveyor and hauled therealong by a scraper .bar mechanism comprising parallel chains interconnected along their common length by scraper bars for conveying the coal from the site of extraction.

In order to ensure a firm grip with the mine floor, the under side of the supporting leg 10, i.e. for example, along the free ends of the U-shaped portion may be provided with downwardly extending projections 24 which sink into the mine floor. Inasmuch as there may be a tendency for the main piston-cylinder arrangement 13 to rotate upwardly about the axis of pivot 20; a loaded spring 25 within a casing 26 is downwardly urged against the upper portionof main cylinder 15 to. oflset any such upward pivotal displacement of the piston-cylinder arrangement As will be appreciated, the secondary or auxiliary piston-cylinder arrangement 16 may be utilized to move the upper pivot 23 farther toward the mine face than the pivot 21 so as to counteract any upward .dsiplacement of the side member'28 of the conveyor 27 which might result in buckling of the arrangement or :the causing of the fcylinder 15 is connected to' the bar .19 such that main cylinder 15 abuts the side member 28 of the conveyor 27 approximately at the height of the trough plate 30. In

this way, main piston-cylinder arrangement 13 .will normally urge the conveyor 27 in the horizontal direction, i.e. at the height of the trough plate 30. By the presence of the secondary piston-cylinder arrangement 16, a higher point of engagement at pivot 23 is provided, such that if secondary piston 18 is urged toward the conveyor 27, -a resultant force is produced via the abutment bar 19 which is directed slantingly downwardly toward the. coal face, such as in the direction of the arrow-32.

While the presence of the secondary piston-cylinder arrangement 16 connected to the main cylinder 15 might otherwise cause a rotation of the arrangement about the pivot 20 on the supporting leg 10, due to the presence of the downwardly urging spring 25, any such tendency is suitably offset. At least, any unilateral lifting of the conveyor in the manner shown in FIG. 1 is minimized by the presence of the spring 25 on the base means.

Where the secondary piston-cylinder arrangement 16 is operated, such that the piston 18 moves away from the conveyor 27, the guiding track 31 might be caused to press against the coal face with a component of force directed slantingly upwardly rather .thanas shown by arrow 32. In such case, the digging 'of the planer. into the mine floor would be prevented, even if the mine floor were soft and friable.

Naturally, the positioning of the main piston-cylinder arrangement and the secondary piston-cylinder arrangement may be reversed, such that the main piston-cylinder arrangement is situated above the secondary piston-cylinder arrangement, yet with the construction permitting the desired angular displacement of the abutment bar 19.. Moreover, it will be appreciated thatthe secondary pis- -ton-cylinder arrangement maybe connected directly or indirectly, and fixedly or pivotally onto the main pistoncylinder arrangement. Furthermore, the angle of pivot of the main piston-cylinder arrangement 13 about the pivot 20 maybe suitably limited by the provision for ad- 'justable stop means on the supporting leg 10, i.e.. above and below the normal horizontal position of the main piston 14 to prevent toohigh or too low a movement of piston 14 w-ithrespect to the normal horizontal disposition thereof. It will be appreciated, from FIG. 1, that by providing the supporting leg 10 as a U-shaped member with the free ends of the U directed downwardly, the main piston-cylinder arrangement 13 will be suitably protected from coal, dirt, dust, etc. which might otherwise clog and damage the operating parts.

As will be appreciated by the artisan, any conventional means may be employed for actuating the piston-cylinder arrangements 13 and 16, as well as the pit prop 11 which may be extended or retracted. Usually, the pit prop takes the form of a hydraulic jack and the piston-cylinder arrangements take the form of hydraulically operated pistons of the double-acting type. More specifically, a reservoir for hydraulic fluid may be connected via separate lines to each end of the particular cylinder in question so that hydraulic fluid may be injected or removed from that portion of the cylinder on the appropriate side of the piston. Such arrangements are Well known and need not be exemplified further herein. The operation to be achieved in any case, of course, is that the piston and cylinder may be actuated to urge the same further into and further out of telescopic engagement with one another, depending on whether the linear displacement desired is to increase the distance between the free end of the piston and the free end of the cylinder or to decrease such distance. This will immediately affect the angular disposition of the abutment bar 19 with respect to the mine floor.

With respect to FIG. 2, an alternate embodiment of the invention is shown including a base means having a supporting leg 33 situated on the mine floor and a vertical prop 34 for engaging the mine ceiling, whereby the base means will be fixed against undesired horizontal displacement thereof. The supporting leg 33 is provided with an upper retaining means 35 and a lower retaining means 36 which are vertically spaced apart from one another such that the carriage 37 which is provided with an upper slide surface 38 and a lower slide surface 39, may be horizontally displaceably received at least along one end portion thereof within the space between the retaining means 35 and 36. In order to prevent undue upward displacement of carriage 37 within the space between the retaining means 35 and 36, adjustable shims are provided in stacked relation between the upper slide surface 38 and the retaining means 35. While the carriage 37 may be displaced in horizontal direction in an undisturbed manner, even though shims 40 are present, this is because the shims are suitably retained against horizontal displacement. If desired, other stop means may be used in place of the shims 40 to limit the upward displacement of the carriage 37.

In the embodiment of FIG. 2, the main piston-cylinder arrangement is disposed above the secondary piston-cylinder arrangement. Thus, main piston 41 slidably received within main cylinder 42 is pivotally connected at its free end to supporting leg 33 by pivot 43, main cylinder 42 being pivotally connected to the abutment bar 45 by the pivot 44. On the other hand, the secondary cylinder 46 is provided with a partition 47 so as to form a separate damping cylinder compartment 48 in which the damping piston 49 is slidably received, the free end of damping piston 49 being pivotally connected to the car-riage 37 at pivot 50. At this point, it should be noted that while damping piston 49 is pivotally connected to the carriage 37, the main cylinder 42 is fixedly connected along at least a portion of its length to the carriage 37 whereby a change in the disposition of main piston 41 within main cylinder 42 will cause the horizontal displacement of carriage 37 with respect to supporting leg 33, while this will not be always true in the case of damping piston 49 and damping cylinder compartment 48. Specifically, secondary piston 51 attached at its free end by pivot 52 to the abutment bar 45 is received within secondary cylinder 46 so as to urge abutment bar 45 against the side member 28 of the conveyor 27. Nevertheless, since cylinder 46 is in fact connected with the damping cylinder compartment 48 due to the presence of the partition Wall 47, and since the damping cylinder compartment 48 is operatively connected with the damping piston 49, undue stresses met by the conveyor upon passage of the planer therealong in engagement with the mine face, will be absorbed by the damping action of piston 49 within chamber 48. This is true since chamber 48 is connected with the reservoir for the hydraulic fluid used for operating the arrangement as noted above in connection with the oper-ation of the pistons and cylinders in FIG. 1. The reservoir pressure will return the damping piston 49 to its normal disposition 49 within the cylinder chamber 48 once the excessive force has been relieved, due to the maintainen-ce of a reference pressure within the reservoir for the hydraulic fluid. However, in the case of cylinders 42 and 46, these cylinders are provided preferably at the ends of the cylinder chambers with hydraulic fluid connections for injecting or withdrawing hydraulic fluid from the .approprate sides of the piston in question. Therefore, the piston-cylinder arrangements may be operated to increase or decrease their length in the usual manner. The same is true with respect to the vertical prop 34 which may take the form of a hydraulic jack similar to the slanting jack 11 of FIG. 1, both such jacks being extensible or retractable as desired.

It will be appreciated that while FIG. 1 is directed to an embodiment in which the main piston-cylinder arrangement is situated below the secondary piston-cylinder arrangement, in FIG. 2 just the opposite construction is achieved. Naturally, the shock absorbing or yielding action provided by the damping piston 49 within the damping cylinder compartment 48 may be utilized in accordance with the embodiment of FIG. 1 as well by merely connecting the piston-cylinder arrangement 16 of FIG. 1 with the piston-cylinder arrangement 13 by a damping piston-cylinder arrangement, etc.

In the case of FIG. 2, the planer guiding track or tube 31 may be pressed against the mine face by the urgence of cylinder 42 under the action of hydraulic pressure against piston 41, such that the point of exertion of the hydraulic force against the side member 28 will be adjacent the pivot 44 of the abutment bar 45. This point is substantially above the intermediately positioned trough plate 30 of the conveyor 27. Thus, if only the main piston-cylinder arrangement is actuated, the track 31 will be urged against the coal face with a downwardly slanting direction of force. In order to prevent the conveyor 27 from lifting from the mine floor at its rear side and in turn the lifting of the main piston-cylinder arrangement about the pivot point 43, the supporting leg 33 is supplied with appropriate stop means, in the embodiment shown such stop means taking the form of adjustable shims 40. Of course, the number of stacked shims 40 and hence the stopping point in upward direction of the carriage 37 and in turn the cylinder 42 can be adapted to the prevailing conditions in each case by adding or subtracting one or more shims from the number then being used.

'Iihe construction of the present invention advantageously permits an accurate and precise urgence of the force of the backing arrange-ment in a particular direction. Thus, in the embodiment of FIG. 2, for instance, if it is desired to urge the conveyor 27 at the side member 28 with a fonce directed approximately parallel to the mine floor, the secondary cylinder 46 may be appropriately actuated to cause the corresponding movement of the secondary piston 51 and in turn the varying of the angular disposition of the abutment bar 45. The presence of the damping piston-cylinder arrangement connected to the hydraulic fluid reservoir or pressure line permits a desired urging pressure to be exerted against the conveyor, not only with the normal force of the cylinder 42 but also with the yieldable force of the cylinder 46, coupled with the damping cylinder compartment 48. By suitable adjustments of the length of extension of piston 51 and cylinder 42, the desired pressure component

Claims

1. BACKING ARRANGEMENT FOR LATERAL URGING ABUTMENT AGAINST A MINING CONVEYOR ADAPTED TO EXTEND LONGITUDINALLY ALONG A MINE FACE TO URGE SUCH CONVEYOR TOWARD THE MINE FACE, WHICH COMPRISES UNITARY BASE MEANS FOR ENGAGING THE MINE FLOOR AND MINE CEILING, FIRST URGING MEANS AND SECOND URGING MEANS, EACH SAID URGING MEANS BEING OPERATIVELY CONNECTED TO SAID BASE MEANS, EACH SAID URGING MEANS INCLUDING A LINEARLY DISPLACEABLE URGING MEMBER HAVING A FREE END REMOTE FROM SAID BASE MEANS, THE LINEAR DISPLACEABLE MEMBER OF ONE OF SAID URGING MEANS BEING OPERATIVELY SITUATED ABOVE THE DISPLACEABLE MEMBER OF THE OTHER URGING MEANS, AN ABUTMENT BAR DISPOSED IN A SUBSTANTIALLY VERTICAL PLANE AND PIVOTALLY CONNECTED BY A SEPARATE RESPECTIVE PIVOT TO EACH OF SAID FREE ENDS TO LINKABLY INTERCONNECT SAID MEMBERS AT THEIR FREE ENDS AND TO PERMIT ANGULAR DISPLACEMENT OF SAID BAR IN SAID VERTICAL PLANE IN RESPONSE TO LINEAR DISPLACEMENT OF AT LEAST ONE OF SAID DISPLACEABLE MEMBERS, WHEREBY DURING ABUTMENT OF SAID BAR AGAINST THE SIDE OF SUCH CONVEYOR REMOTE FROM THE MINE FACE SAID FIRST AND SECOND URGING MEANS WILL URGE SAID CONVEYOR TOWARD THE MINE FACE WITH A RESULTANT DIRECTION OF FORCE WHICH VARIES IN DEPENDENCE UPON THE ANGULAR DISPOSITION OF SAID BAR WITH RESPECT TO THE MINE FLOOR.