US3372792A

US3372792A - Apparatus for bracing a longitudinal mining conveyor

Info

Publication number: US3372792A
Application number: US436397A
Authority: US
Inventors: Lobbe Armin
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1964-02-28
Filing date: 1965-03-01
Publication date: 1968-03-12
Anticipated expiration: 1985-03-12
Also published as: DE1219429B

Description

March 12, 1968 APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Filed March 1, 1965 5 Sheets-Sheet 1 /NVEN T 0R ARM/N LOBBE A. LOBBE 3,372,792

March 12, 1968 V A. LCBBE 3,372,792

APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Filed March 1, 1965 3 Sheets-Sheet 2 H YD. PRESSURE RETURN f HYD. PRESSURE INVENTQR ARM/N LOBBE March 12, 1968 A. LGBBE 3,372,792

APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Filed March 1, 1965 3 Sheets-Sheet 5 I 43 REruR/v HYD.

34 RREssuRE HYD. PRESSURE Q/NVENTOR ARM/Iv LO'BBE United States Patent Ofilice 3,372,792 Patented Mar. 12, 1968 3,372,792 APPARATUS FOR BRACING A LONGITUDINAL MINING CONVEYOR Armin Liibbe, Oberaden Post Kamen, Germany, assignor to Gewerkschaft Eisenhutte Westfalia, Wethrnar, near Lunen, Westphalia, Germany, a corporation Filed Mar. '1, 1965, Ser. No. 436,397 Claims priority, application Germany, Feb. 28, 1964, G 39,974 12 Claims. (Cl. 198126) ABSTRACT OF THE DISCLOSURE This specification discloses a novel prop means adapted to brace a mining conveyor against the floor and roof of a mine, so constructed that the mining conveyor is capable of moving toward and away from the mine seam plane without disturbing the propping action. This apparatus consists of a mining conveyor having an elastically extensible prop member pivotally connected to the side thereof away from the mine face, which prop mem ber has a cap pivotally connected therewith which impinges upon the mine roof as the mining conveyor proceeds towards or away from the mine face, the prop member extends or retracts elastically without altering the contact thereof with the roof.

This invention relates in general to an apparatus for bracing a longitudinal mining conveyor and more particularly to such an apparatus having one or more extensible propping members connected to the conveyor for engagement with a roof of a mining seam, and which exert load forces to brace the conveyor against the floor of the mining seam.

Generally, in the mining of coal and other mineral material, a planing device is often used to extract coal from the mine seam face. In this regard, the planing device is moved against the coal face whereby a layer of coal is scraped from the adjacent mine wall. In order to conveniently remove the extracted coal from the site of mining operations, a longitudinal conveyor is provided adjacent to the mine face along the path of travel of the planing device.

Accordingly, as the planing device extracts coal, by reason of the positioning of the conveyor, the coal falls thereon and is conducted from the site of mining operations.

in particular, double chain scraper conveyors are used wherein a pair of parallel endless chains are provided mounted for movement in the same direction so as to carry the coal by means of the attendant chain scraper bars along the surface of the conveyor to a distant point of recovery. The planing device may be conveniently supported in a track disposed along the conveyor and afilxed thereto on the side adjacent to the mine face being extracted.

As each layer of coal is scraped from the mine face, the planing device is moved forward in a transverse direction so that it may engage the next layer of coal. Simi larly, the conveyor is advanced to accommodate the newly extracted coal.

One of the problems encountered in such mining operation is that of maintaining the coal plane track, which is usually mounted laterally on the conveyor, in a fixed position with respect to the mining seam floor such that the coal plane cuts the mining face flush with the floor. Where coal is to be out along an inclined coal bed, it has been found that the coal plane guide track frequently rises above the floor as the result of the high tensions in the conveyor coal chain and the coal plane drive chains, thereby causing said plane to climb upward as it cuts, leaving an uncut layer of coal on the floor.

To remedy this problem it has been proposed to press the conveyor tightly against the floor by means of props braced against the roof. However, this proposed solution is not satisfactory in the case of conveyors and coal planers that are automatically advanced as the coal mining progresses, since the props have to be removed and reset with each advancement step, an operation which is troublesome and time-consuming whether the props be wooden props cut to length, or extensible props, such as those that are pneumatically or hydraulically operated.

The apparatus of the instant invention eliminates this disadvantage of prop setting, and yet provides for positive bracing of the conveyor against the floor, by using one or more extensible propping members pivotally connected to the conveyor, or to a rigid support member such as a foot member which is affixed to the conveyor, and a cap member for each propping member which is pivotally connected thereto for hearing engagement with the roof of the mining seam.

The extension length and load force exerted by such a propping member can be selectively adjusted to maintain the cap member in bearing engagement with the roof and to brace the conveyor against the floor, with said bracing being maintained when the propping member is articulated to permit the conveyor to be displaced in a direction transverse to the mining seam face, by providing means which permit the propping member to yield elastically. In the case of propping members which are hydraulically operated, and are in effect extensible linear actuators, this elastic yielding can be accomplished by means of a hydraulic expansion reservoir, which is flow connected to the fluid pressure chamber of the propping member during articulation, so that as the length of said propping member is reduced or increased during its articulation, the expansion reservoir acts as a hydraulic spring to allow fluid to flow from the propping member into the reservoir when said propping member is shortened, and to force fluid back into the propping member when it is lengthened.

Thus, for example, when the propping member is to be articulated from an initial position which is inclined away from the mining face to a final position which is inclined toward said face, with the cap member being maintained in sliding bearing engagement during the articulating movement, the length of the propping member must first necessarily decrease to a minimum in travelling from the initial background inclined position to a. position perpendicular to the roof, and the increase in length as the propping member is swung to the forward inclined position. Accordingly, by reason of the spring effect provided by the expansion reservoir, the cap member is always urged with some force against the roof, even when the propping member is articulated, and although this force is not necessarily the same as is exerted when the propping member is connected directly to its normal hydr-aulic pressure source, the elastic force provided by the expansion reservoir can be made sufiicient to brace the conveyor against the floor. As can be readily appreciated by those skilled in the art, it is necessary to remove hydraulic fluid from the propping member in order to shorten it, and to add fluid thereto in order to lengthen it, due to the substantial incompressibility of liquid hydraulic fluids.

In the typical operation of the apparatus according to the invention, the bracing of the conveyor can be accomplished with the propping members inclined up to a certain limit angle about the perpendicular to the roof from their pivot connections to the conveyor. This arrangement permits the propping members to be advanced stepwise by articulation as the conveyor is advanced. For example, assuming that a propping member is initially inclined at the limit angle toward the mining face, said propping member can be elastically relieved to permit the conveyor to be advanced toward the mining face by a distance corresponding to an articulation which inclines the propping member at a backward limit angle, with its cap member remaining in a fixed position against the roof. Then, with the conveyor remaining stationary, and the propping member still elastically relieved, said propping member can be swung forward about its pivot connection to the conveyor, with the cap member sliding forward along the roof, to bring said propping member into its forward limit angle inclination position, thus placing it in an appropriate configuration for a successive advancement step for the conveyor. At the end of each articulation of the propping member, its pressure chamber can be disconnected from the expansion reservoir and connected to the hydraulic pressure source to increase the bracing force. It should be noted that when a propping member is initially inclined toward the coal face, the conveyor can be advanced for a maximum step distance before the propping member and its cap member must be swung forward. This distance corresponds to the path length on the roof swept by the cap member as the propping member is swung from its backward to its forward limit angle positions.

This shifting of the cap members ordinarily will not be necessary until after several cutting passes of the coal plane, the exact number of passes per cap member shift depending upon the depth of cut per pass, and the height of the roof above the propping member pivot axis.

The advancement of the conveyor and its associated coal plane track can be accomplished by means independent of the propping apparatus, such as for example, by advancing actuators connected to separate advanceable propping systems, or by a linear actuator which can be used for both articulating the conveyor propping members and advancing said conveyor, as provided by another embodiment of the invention.

According to the instant invention, the propping members used for bracing the conveyor are pivotally connected to its side members, with the pivot axes in each case being substantially parallel to the longitudinal axis of said conveyor.

Similarly, the cap member is pivotally connected to the extensible upper portion of the propping member with its pivot axis being parallel to that of the lower portion of said propping member which is connected to the conveyor. The cap member is so constructed as to have a plate-like portion which is adapted to engage the roof surface, which can be somewhat irregular.

It has been found advantageous to provide the conveyor with a foot member affixed thereto on the waste side of the conveyor, said foot member being provided with runners which rest upon the floor, and to pivotally connect the propping members to such a foot member rather than to the conveyor directly. With this arrangement the propping members do not interfere with the clearance profile of the conveyor. Also, by using such foot members, it is thus possible to provide propping members for bracing the conveyor at any point along the length of its sides as may be required for improved bracing action, since such foot member and propping member arrangements can be conveniently and quickly fastened to the conveyor such as for example, by bolting.

As long as such a propping member is urged with sufficient force against the roof, it will remain in its more or less inclined or perpendicular position without any further securing. However, a spring such as for example, a laminated leaf spring, can be provided for the purpose of maintaining such a propping member in a raised, inclined position. if desired, a hydraulic actuator can be substituted for this purpose. in either case, the spring or hydraulic actuator are preferably arranged and attached so that they urge the prop member into its forward position in the direction of the coal face. Such an arrangement renders the shifting of the propping member more convenient since, as soon as the conveyor has advanced to such an extent that the propping member has reached its limit rearward inclination, all that needs to be done is to briefly relieve its pressure against the roof, and it will then be swung automatically back into its forward position under the effect of the spring or actuator.

Where a hydraulic actuator is used for articulating the propping member, said actuator can be pivotally connected at one end to a support member, or foot member attached to the conveyor, and pivotally connected at the other end to the propping member.

By connecting such an actuator to an independent propping member, such as a follower propping member, said actuator can also serve for advancing the conveyor. In such an arrangement it is preferable that the piston rod of the actuator be pivotally connected to the propping member at a location close to the pivot connection of said propping member to the conveyor or foot member, so that the largest possible component of force exerted by the actuator will serve for advancing the conveyor toward the coal face, while also providing a sufficient but slight force for the purpose of swinging the propping member back to its forward position after its pressure against the roof has been elastically relieved.

If desired, propping members can be connected to the coal-face side of the conveyor in addition to, or instead of the propping members connected to its waste side. In such an arrangement, it is expedient to connect the propping members on the coal-face side to articulate in the same plane as the oppositely connected propping members on the waste side, such as for example, by a linking member connecting pairs of opposite propping members, or by articulating their cap members to one another. Furthermore, the pressure chambers of such articulately connected propping members can be operated from a common hydraulic control means.

According to the instant invention, the hydraulic fluid flow to and from such actuators and hydraulic propping members can be performed automatically by means of control valves operated in response to the angular position of the propping members so that the sequence of articulating motions that must be performed with each advancement step of the conveyor can be performed automatically.

It is therefore, an object of the invention to provide an apparatus for bracing a mining conveyor and its associated coal plane track against the floor of a mining seam, so that the coal plane will remove coal from the mining face down to a level which is flush with the seam floor.

Another object of the invention is to provide an apparatus as aforesaid wherein the bracing of the conveyor and coal plane track is maintained during the advancement thereof, so that on successive coal planing operations. coal from the mining face will be removed down to the floor.

Still another and further object of the invention is to provide an apparatus as aforesaid having articulating advanceable propping members which can be attached as required to various locations along either or both sides of the conveyor.

Another object of the invention is to provide an apparatus as aforesaid wherein the articulation of the propping members can be performed automatically with each advancement of the conveyor.

Other objects and advantages of the invention will become apparent from the following detailed descriptions and accompanying drawings in which:

FIG. 1 is a tranverse cross section of a mining seam, showing operating arrangement of an apparatus according to a preferred embodiment of the invention.

FIG. 2 is a plan view of FIG. 1

FIG. 3 is a transverse section to a mining seam, similar to that of FIG. 1, showing an operating arrangement of an apparatus according to another preferred embodiment of the invention.

FIG. 4 is a schematic illustration of a hydraulic control system for the apparatus of FIG. 1.

FIGS. 5A and 5B are schematic illustrations of a modified hydraulic control system for the apparatus of FIG. 1.

Referring now to FIGS. 1 and 2, which show an apparatus A according to the invention for bracing a conveyor trough 10, a ramp-like guide rail 11 for a coal plane 12 is attached to the coal-face side of the conveyor 10. For simplicity, the circulating drag chain used for pushing coal over into the conveyor has been omitted.

The coal plane 12 is driven in alternating directions along the coal-face 14 by a chain 13, which is in turn driven by a prime mover (not shown).

For an eficient mining operation, it is essential that the plane 12 cut away coal from the coal-face 14 all the way down to the level of the floor of the mining seam. To accomplish this, it is necessary that the guiding track 11 and attached conveyor 10 be maintained in such a position, preferably against the floor 15, that the plane 12 can cut flush with the level of said floor 15.

It has been found, especially in inclined mining seams, that the highly tensioned conveyor chains (not shown), and the coal plane 12 drive chain 13 tend to lift the conveyor 10 and track 11 up away from the floor 15, thereby causing the plane 12 to climb upward, leaving a layer of uncut coal extending above the level of said floor 15.

According to the invention, the conveyor 10 and guide track 11 are braced against the floor 15 by means of an apparatus A, having an extensible propping member 16 which is pivotally connected by a pin 17 to a foot member 18 which is fixedly, but releasably connected to the conveyor 10. If desired, this pivotable connection can be made directly to the conveyor 10 or to any suitable support member (not shown) attached thereto. However, the use of a foot member 18 which can be releasably connected to the conveyor 11) for carrying the pivotal connection 17 of the propping member 16 has been found to be more advantageous, since such a foot member 18 can be attached to the conveyor 10 at a multiplicity of selected locations thereon, and additional members 16 can be attached to said conveyor 10 as desired or required along its length.

The foot member 18 is preferably provided with runners 19 at its bottom, said runners 19 being disposed perpendicular to the coal-face 14, and are adapted for hearing engagement with the floor 15. Depending upon the arrangement of the guide track 11 with respect to the conveyor 10, the foot member 18 can be connected to said conveyor 10 so as to maintain both the foot member 18 and conveyor 10 in contact with the fioor 15, or said foot member 18 and conveyor 10 can be connected so that the conveyor 10 is maintained at a fixed spacedapart distance from the floor 15 when the runners 19 of the foot member 18 are in contact with said fioor 15, the choice of foot member 18 to conveyor 10 connection arrangement being preferably the one which holds the track 11 in a position which causes the coal plane 12 to cut the coal-face 14 down to the level of said floor 15.

The propping members 16 are preferably of the conventional hydraulically operated type, which are substantially equivalent in operation to hydraulic linear ac- Iuators in that they have a pressure chamber or cylinder 30 and a piston member 31 slidably disposed therein. By means of the hydraulic pressure control system shown in FIG. 4, said propping member 16 can be selectably adjusted in its extension length as well as in the load force it exerts to brace the foot member 18 and conveyor 10 against the floor 15.

Under the effect of the hydraulic fluid transmitted from a source (not shown) by means of a hydraulic line 20, the cap member 16 which is pivotally connected to the piston or upper member 31 of said propping member 16 is urged into bearing engagement against the roof 21 so that the load force exerted by the propping member 16 acts to brace the foot member 18 against the floor 15.

By placing the pressure cylinder 30 of the propping member 16 in flow connection with the hydraulic expansion reservoir 24 as indicated by FIG. 4, the propping member 16 can be rendered elastic, so as to have extension properties equivalent to those produced if a compression spring (not shown) were introduced into the pressure cylinder 30, instead of hydraulic fluid. This elasticity serves to maintain the upper member 31 yieldingly extend-ed, but under pressure to maintain the cap member 16' in bearing contact with the roof 21 as the propping member 16 assumes various inclined positions when it is articulated from a forward limit inclination angle to backward limit inclination angle as shown by the broken outlines I and II in FIG. 1.

This articulation capability is advantageous in that it permits conveyor 10 to be braced with respect to the floor 15 during times when it is displaced in a direction transverse to the coal-face 14, and also permits such a displacement to be performed. Without elastically relieving the hydraulic pressure in the cylinder 30, as by allowing it to flow into an expansion reservoir 24, the incompressibility of the fluid in said cylinder 31} would prevent the advancement of the conveyor 10 and coal plane 12 toward the coal-face 14.

The advancing of the conveyor 10 and its associated coal plane 12 can be accomplished by independent actuators 22, preferably hydraulic, which are braced against roof props 23, and are connected to the: conveyor 10 as indicated by FIG. 2.

The basic operation of the bracing apparatus A, can be best explained by assuming that the propping member 16 is in an initial position I as indicated by the broken outline of FIG. 1, wherein said propping member 16 is inclined at its forward limit angle, and that it is desired to advance the conveyor 10 toward the coal-face 14 as indicated by the full line configuration of FIG. 1. To accomplish this the propping member 16 is elastically relieved by connection to the expansion reservoir 24, and the actuators 22 are operated to advance the conveyor 10 toward the coal face 14. As the conveyor 10 is so advanced, the propping member 16 is first shortened and then lengthened elastically as it articulates from its backward limit angle position to its forward limit angle position, as indicated by the broken outlines I and II of FIG. 1. During this articulation, the cap member 16' remains fixed in its original position, and braces the conveyor 10. When the propping member 16 is in the forward limit angle position II, it is again articulated forward, with the cap member 16 being swept along the roof 21 until the propping member 16 and cap member 16' are: in the full line position of FIG. 1. During the second articulation the conveyor 10 is held stationary.

This procedure can be repeated to successively advance the conveyor 10 during the progress of coal mining, and need not be performed in two steps, as in the case where it is desired to continuously advance the conveyor 10.

The apparatus A of the instant invention is adaptable to the gradual and continuous advancement of the conveyor 10 since it makes no dilference in the bracing action whether the propping member 16 is gradually articulated between its limit angle positions or is stepwise articulated. However, in the case of the stepwise articulation of said propping member 16 and advancement of the conveyor 10, the hydraulic pressure loading of said propping member 16 can be raised to a higher level at the end of each step, so as to provide firmer bracing, whereas in the case of gradual continuous advancement where the propping member 16 must be maintained in an elastically yielding condition, an extreme hydraulic pressure loading would not be feasible. Since a sulliciently high pressure loading can be maintained for adequate bracing of the conveyor 10 even where the propping member 16 is in the elastic yielding condition, provided that sufficient force is available from the advancing actuators 22, there should be no difficulty encountered where it is desired to advance the conveyor 10 continuously.

According to the preferred embodiment of the invention exemplified by FIGS. 1 and 2, the articulation of the propping member 16 is performed by means of a hydraulic linear actuator which can also be operated from the hydraulic line 23 by means of the control valve arrangement of FIG. 4.

Since, ordinarily, it will be desired only to swing the propping member 16 into a forwardly inclined position, a spring (not shown), such as for example a leaf spring (not shown) can be substituted for the actuator 25. As shown in FIG. 4, the actuator 25 is connected by a line 32 to a control valve 33, preferably a three-way valve, which is connected to the hydraulic pressure line 20, and the return line 34 from the hydraulic pressure source (not shown), said return line 34 being at a lower pressure than the line 20. The valve 33 is capable of selectably connecting the line 32 to either the pressure line 20 or to the return line 34.

The pressure cylinder of the propping member 16 is connected by a line 35 to another control valve 36 which is also a three-way valve, and which serves to selectably connect the cylinder 36 to either the pressure line 21), or to a line 37 which is connected to the expansion reservoir 34.

When it is desired to articulate the propping member 16 either forward or backward, the valve 36 is operated to place the cylinder 30 and expansion reservoir 34 in flow connection, thus enabling said propping member 16 to yield and extend elastically.

When it is desired that the propping member 16 be articulated backwardly as when the conveyor 10 is advanced, the valve 33 is operated to place the actuator 25 in flow connection with the return line 34, so that the fluid in said actuator can flow back to the source as its piston 38 is pushed into the cylinder 39 thereof by the backward articulation of the propping member 16.

To provide for bracing the actuator 25 so that it is effective to articulate the propping member 16, its cylinder 39 is pivotally connected to the foot member 18 by a pin 40, and its piston 38 is pivotally connected to the cylinder 39 of the propping member 16 by a pin 41.

When it is desired to articulate the propping member 16 in the forward direction, as when the cap member 16 is to be swept long the roof 21, the valve 33 is operated to place cylinder 39 of said actuator 25 in flow connection with the pressure line 2t), so that the piston 38 is forcibly urged Outward therefrom to articulate the propping member 16 forward.

The two views (A) and (B) of FIG. 5 schematically illustrate another hydraulic control arrangement whcih can be use-d in conjunction with the apparatus A of FIGS. 1 and 2.

In this particular arrangement, the propping member 16a is a double-acting hydraulic linear actuator having a lower cylinder portion 30a and an upper cylinder portion 30b and a piston 31. The cylinder 39 of the actuator 25 is flow connected with the upper cylinder portion 3011 by a line 42, said line 42 being also connected to a threeway control valve 43 by a line 44. The lower cylinder portion 30a is connected by a line 45 to another three-way control 46. The

valves

43 and 46 are connected to each other by a line 47, which in turn is connected by a line 48 to a three-way control valve 49. In addition, the

valves

43 and 46 are connected to the return line 34 by

lines

50 and 51, respectively. A line 52 connects the valve 49 to the expansion reservoir 24.

The view (A) shows the propping member 16a in its forward inclination limit position, with its lower cylinder portion 33a connected via the

valves

46 and 49 to receive elastically pressurized fluid from the reservoir 24, with its upper cylinder portion 30b and the cylinder 39 of the actuator 25 being connected via the valve 43 to the return line 34. Under such conditions, the piston 31 is driven outward and upward to press the cap member 16 firmly against the roof 21, and the actuator 25 is de-e-nergized. If desired, firmer bracing can be obtained by switching the valve 49 to cut out the reservoir 2.4, and to connect the line 48 directly to the pressure line 2-0.

In the valve positions (

valves

43, 46, and 49) shown in view (A), the propping member 16a can be articulated 'backwardly with the cap member 16' remaining fixed against the roof 21 simply by pushing the conveyor 14 and foot member 13 forward. With the upper cylinder portion 38b and the actuator 25 connected to the return line 34, the piston 31 will be extended and retracted automatically by the elastic action of the reservoir 24.

When the propping member 1611 has arrived at its backward limit angle position, such as indicated by view (B), the valve 43 is operated to connect the actuator 25, cylinder 39 and the upper cylinder portion 33b to receive pressurized hydraulic fluid, and the valve 46 is operated to connect the lower cylinder portion 30a to the return line 34. The valve 49 can be operated to connect the reservoir 24 into the pressure line 20, or if desired, the reservoir 24 can be cut out entirely. Under these conditions, the piston 31 is driven inward, relieving pressure exerted by the cap member 16 against the roof 21 momentarily, as the propping member 16a is swung forward by the energized actuator 25.

The backward and forward articulation of the propping member 16a can be performed automatically by means of a switching mechanism 53 which is responsive to the angular position of said propping member 16a, or by a switching member 53 which is responsive to the extension of the actuator 25, since in the arrangements shown in FIG. 5, the extension of said actuator 25 is directly related to the angular position of the propping member 16a. in either case, the mechanism 53 operates the

valves

43, 46 and 49 in response to the angular position of the propping member 16a so as to accomplish the desired articulation thereof automatically. As to the details of the mechanism 53, any conventional switching device suitable for the purpose can be used. Where the

valves

43, 46 and 49 are electrically operable, such as solenoid controlled valves, the switching mechanism 53 is preferably an electrical switching device.

It will be appreciated by those skilled in the art, that other valve switching sequences and control arrangements can be substituted for those described herein by way of example.

As can be noted in FIG. 1, another propping member 27, indicated in broken lines, can be provided in addition to or instead of the propping member 16. This propping member 27 serves to provide additional bracing for the conveyor 19, and is articulately connected thereto at its coalface side, and is provided with a pivotally connected cap member 27'.

The propping member 27 is preferably arranged so as to assume a position parallel to that of the propping member 16. This can be achieved by connecting the cap member 16 and 27' articulately, such as by a link member 54. If desired, the link member 54 can be alternatively connected directly to the propping members 1.6 and 27, so that the same means used for articulating the propping member 16 will produce a corresponding articulation in propping member 27. The extension length and load force exerted by the propping member 27 can be controlled by simply connecting its pressure cylinder 55 in parallel with the hydraulically operated cylinder 30 of propping member 16.

A somewhat different embodiment of the invention is shown by the apparatus A of FIG. 3. The propping member 16 in this case is urged forward towards the coal face 14- by advancing cylinder 28, which is in turn braced against a sprag 29. This arrangement offers the advantage that the same pressure cylinder 28 can perform both the function of advancing the conyeyor it} along with the coal plane guide track 11, and the function of articulating the propping member 16 as previously described herein. If desired, a separately advanceable propping system (not shown) can be substituted for the sprag 29.

What is claimed is:

1. An apparatus for bracing a mining conveyor against the floor of a mining seam having a floor, a roof, and a mining face which comprises:

(a) an extensible propping member connected at one end to the mining conveyor through pivot pins which are disposed substantially parallel to the longitudinal axis of said conveyor, and adapted to be positioned in a plane substantially perpendicular to said axis;

(b) a cap member pivotally connected to the opposite end of said propping member for hearing engagement with the roof of the mining seam;

(c) means for selectively adjusting the extension length and load force exerted by said propping member to maintain the cap member in bearing engagement with the roof and brace the conveyor against the floor, and to maintain said bracing of the conveyor when the propping member is articulated to permit said conveyor to be displaced in a direction transverse to the seam face; and

(d) resilient force structure in constant reaction with said propping member.

2. The apparatus according to claim 1 including a rigid support member fixedly connected to the conveyor, and an extensible linear actuator for articulating the propping member, said actuator being pivotally connected at one end to said propping member and pivotally connected at the opposite end to said support member, and means for selectively adjusting the extension of said actuator to articulate said propping member.

3. The apparatus according to claim 1 including a bracing member disposed in fixed spaced relation to the face of the mining seam, an extensible linear actuator for selectively displacing the conveyor in a direction transverse to said seam face and articulating the propping member, said linear actuator being pivotally connected at one end to the bracing member, and pivotally connected at the opposite end to said propping member, and means for selectively adjusting the extension of said actuator to displace the conveyor and articulate the propping member.

4. The apparatus according to claim 1 wherein the extensible propping member is a hydraulic linear actuator, and the means for selectively adjusting the extension length and load force exerted by said propping member includes a source of pressurized hydraulic fluid, a hydraulic fluid expansion reservoir, and a control valve flow connected to said reservoir, to the propping member, and to the hydraulic fiuid source, said valve being selectively operable to place the propping member in flow connection with the source, and to place said propping member in flow connection with the reservoir, whereby when said propping member is to be articulated, the valve is operated to place the propping member in flow connection with the reservoir, thereby enabling said propping memher to ext-end and contract as required for its articulation, and to maintain the conveyor braced against the floor during such articulation with a load force which is established by the quantity of hydraulic fluid transferred from the propping member into the reservoir, and at the end of said articulation, the valve is operated to place the propping member in flow connection with the hydraulic fluid source to increase the bracing force acting on the conveyor.

5. The apparatus according to claim 4 including a hydraulic linear actuator which is selectively extensible for articulating the propping member, said actuator being pivotally connected at one end to said propping member and pivotally connected at the other end to a support member which is fixedly connected to the conveyor, a source of pressurized hydraulic fluid, said source having a pressure line and a return line, and a control valve flow connected with said actuator, and with said pressure and return lines, said valve being selectively operable to place the actuator in flow connection with the pressure line for articulating the propping member in a. direction toward the mining face, and to place said actuator in flow connection with the return line to permit said propping member to be articulated in the reverse direction.

6. An apparatus for bracing a mining conveyor With respect to the floor of a mining seam having a floor, a roof and a mining face, which comprises:

(a) an articulatable elastically extensible hydraulic propping member having means for bearing engagement with the roof adapted to exert a thrust on said mining conveyor during articulation thereof;

(b) means for pivotally connecting said propping member to the conveyor;

(c) hydraulic means for selectively adjusting the extension length and load force exerted by said propping member to brace the conveyor with respect to the floor and for maintaining said bracing when the propping member is articulated;

(d) an actuator for articulating said propping member from a backwardly inclined position;

(e) control means responsive to the inclination angle of said propping member for controlling the operation of said actuator; and

(f) resilient force structure in constant reaction with said propping member.

7. An apparatus for maintaining an advanceable mining conveyor in fixed spaced-apart relation to the floor of a mining seam having a floor, a roof, and a mining face, which comprises:

(a) a foot member fixedly connected to the conveyor,

said foot member being supported in bearing engagement by the floor;

(b) an elastically extensible propping member connected at one end to said foot member through pivot pins which are disposed substantially parallel to the longitudinal axis of said conveyor, and adapted to be positioned in a plane substantially perpendicular to said axis;

(c) a cap member pivotally connected to the opposite end of said propping member for bearing engagement with the roof;

(d) means for selectively adjusting the extension length and load force exerted by said propping member to maintain the cap member in bearing engagernent with the roof, and the conveyor in fixed spacedapart relation to the floor by bracing the foot member against said floor, and to maintain said bracing when the propping member is articulated to permit said conveyor to be displaced in a direction transverse to the seam face; and

(e) resilient force structure in constant eraction with said propping member.

8. The apparatus according to claim 7 wherein the conveyor is connected to the foot member in an arrange ment whereby both the foot member and the conveyor are in bearing engagement with the floor.

9. The apparatus according to claim 7 including an extensible linear actuator for articulating the propping member, said actuator being pivotally connected at one end to said propping member, and pivotally connected at the opposite end to the foot member, and means for selectively adjusting the extension of said actuator to articulate said propping member.

10. An apparatus for bracing a longitudinal mining 11 i conveyor against the floor of a mining seam having a floor, a room, and a mining face, said conveyor having a pair of oppositely disposed side members, one of which faces the mining face, with the other facing the waste side of the mining seam, which comprises:

(a) a foot member fixedly connected to the Waste side member of the conveyor, said foot member being supported in bearing engagement by the floor;

(b) a first elastically extensible propping member connected at one end to said foot member through pivot pins which are disposed substantially parallel to the longitudinal axis of said conveyor, and adapted to be positioned in a plane substantially perpendicular to said axis;

(c) a first cap member pivotally connected to the opposite end of said first propping member for bearing engagement with the roof;

(d) a second extensible propping member pivotally connected at one end to the mining face side member of the conveyor;

(e) a second cap member pivotally connected to the opposite end of said second propping member for bearing engagement with the roof;

(f) means for selectively adjusting the extension lengths and load forces exerted by said first and second propping members to maintain their respectively connected cap members in bearing engagement with the roof, and to hold the conveyor braced 1?. against the floor, and to maintain said bracing when the propping members are articulated to permit the conveyor to be displaced in a direction transverse to the seam face; and

(g) resilient force structure in constant reaction with said propping member.

11. The apparatus according to claim 10 including linkage means operatively connected to the first and second propping members for articulating them in synchronism.

12. The apparatus according to claim 11 including an extensible linear actuator for articulating the propping members, said actuator being pivotally connected at one end to the foot member, and pivotally connected at the opposite end to the first propping member, and means for selectively adjusting the extension of said actuator to articulate said propping members.

References Cited UNITED STATES PATENTS 3,072,241 1/1963 Rosenberg et a1. 198-126 3,113,661 12/1963 Linke et a1. 198l26 EDWARD A. SROKA, Primary Examiner.

EVON C. BLUNK, Examiner.

A. C. I-IODGSON, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,372,792 March 12, 1968 Armin Lobbe It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 7 and 8, "mining" should read winning line 50, "the increase" should read then increase Column 6, line 62, "mining" should read winning Column 7, line 53,-"long" should read along Column 10, line 62, "eraction" should read reaction Column 11, line 2, "a room" should read a roof Signed and sealed this 25th day of November 1969.

( Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents