US3186179A - Advanceable mining support arrangement - Google Patents

Description

June 1, 1965 w. VETTER ADVANCEABLE MINING SUPPORT ARRANGEMENT 2 Sheets-Sheet 1 Filed April 10, 1962 June 1, 1965 w. VETTER 3, 7

ADVANCEABLE MINING SUPPORT ARRANGEMENT Filed April 10, 1962 2 Sheets-Sheet 2 l|llIIlllllllllllllllllllllll 1||llllllllllllllllllllllliill| IlllllHHIIIHIIIIIHIIHIIIIII HIHHUI M II HW H HIHIIIIIIIIIIIIHHIIIIIIH ullllllllllllltlli l i I n IHHIHIH 1H;

:IIIIIII HIM //vv NTOR eVre United States Patent G 33,072 15 Claims. (Cl. 61-45) The present invention relates to an advanceable mining support arrangement with adjustable prop means for engaging the mine ceiling and mine floor, and more particularly to such an arrangement having a moving means capable of forward and rearward movement interconnected with four prop means formingtwo diagonally connected prop sets for alternate actuation in the moving direction.

In mining operations carried on for the extraction of mineral from a mine face, it is known to use an advanceable prop frame arrangement which serves to support the overhead seam or mine ceiling. These arrangements are known as walking frames or advancing frames. Specifically, for example, one proposal has been to combine a pair of prop frames into a common unit, with the prop pairs positioned parallel with respect to one another in such a manner that the moving means will alternately shift one frame in the forward direction and thereafter the other frame. For this purpose, a double acting pistoncylinder arrangement is commonly employed with one prop frame being connected for movement with the cylinder and the other prop frame connected for movement with the piston. The advancing is actually achieved by reason of the fact that one frame is placed into engage ment with the mine floor and mine ceiling via the pit props while the other frame is disengaged for movement in the desired direction, the engaging prop frame contributing the desired leverage. Once the advance has taken place in this manner, the disengaged frame is engaged with the mine ceiling and mine floor so that the engaged frame may be disengaged for advancing in its turn.

A further proposal has been made in which the two frames of each pair are alternately moved in the forward direction by means of a separately assigned moving means, i.e., a separate piston-cylinder arrangement. In this instance, the disengaged frame is moved forward by its own piston-cylinder arrangement, and thereafter this frame is placed in engagement and the already engaged frame is disengaged and moved in forward direction by reason of its own piston-cylinder arrangement.

An even further improvement which has been proposed is one in which a piston-cylinder arrangement is provided which is connected with the respective prop frames so that transverse or diagonal movements may be carried out between the piston-cylinder arrangement and the prop frames, otherwise normally parallel to the advancing direction. In the case of these prop frames, guide rods are provided with respect to the props whereby during the advancing a flat circular arc may be executed to change the disposition of the prop frames with respect to the longitudinal direction of the piston-cylinder arrangement.

All of the aforementioned types of advancing frame arrangements which use piston-cylinder arrangements as moving means suffer from the disadvantage that during the advancing of one frame with respect to the other, the distance apart of the prop means in general increases .by more than twofold. Although support of the overhead seam or ceiling within the range of working or advancing is absent for only a short time interval, due to the fact i present. Specifically, where aplural. number of parallel 3,186,179 Patented June 1,1965

pairs of frames are used along a mine face, generally the prop frame on one side of every pair is disengaged simultaneously for advancement, and then the prop frame on the other side. The total lack of support along the entirety of the mine face thus signifies a safety consideration in mining operations.

It is an object of the present invention to overcome the foregoing drawbacks and to provide an advanceable mining support arrangement with adjustable prop means for engaging the mine ceiling and mine floor which permits a more equal distribution of the supporting forces over the area occupied by the arrangement so as to avoid the danger of collapse of the mine ceiling. 7

Other and further objects of the invention will become apparent from a study of the within specification and ac companying drawings in which:

FIG. 1 is a schematic top view, partially in section, illustrating one embodiment of the invention and indicating in phantom the alternate position for two of the mine props present,

FIG. 2 is a schematic partial sectional view taken along the line AA of FIG. 1,

FIG. 3 is a schematic partial side elevation view of the embodiment shown in FIG. 1,

FIG. 4 is a schema-tic partial top view of the linkage of the embodiment of FIG. 3 shown in extended position,

FIG. 5 and FIG. 6 represent schematic top views of a plurality of pairs of mining support frame arrangements representing the prior art and the present invention respectively.

It has been found in accordance with the present invention that an improved advanceable mining support arrangement with adjustable pit prop meansfor engaging the mine ceiling and mine floor may be provided, said arrangement comprising moving means having a forward and a rearward end, first prop means positioned adjacent said forward end on one side of the moving means, and second prop means positioned adjacent the rearward end on the opposite side of the moving means, the first and second prop means together forming a prop set and being connected with the moving means for simultaneous forward and rearward movement, and third prop means positioned adjacent the forward end on said opposite side of the moving means, and fourth prop means positioned adjacent the rearward end on said one side of the moving means, the third and fourth prop means together forming a prop set and being connected with the moving means for simultaneous forward and rearward movement alternately with the movement of the first and second prop means.

Preferably, the moving means includes a'double-acting piston-cylinder arrangement with the piston connected with one of the prop sets for simultaneous movement and the coacting cylinder connected with the other of the prop sets for simultaneous movement alternately with the movement of the first-mentioned prop set.

In accordance with the preferred embodiment, the prop means :of one set are interconnected by a first diagonal cross-element and the props of the other set are interconnected by a second diagonal cross-element overlying the first cross-element. The adjacent cross-portions of the cross-elements are disposed in sliding abutment with each other. Specifically, the piston-cylinder arrangement includes a double-ended cylinder and a double-ended piston rod extending through the corresponding ends of the cylinder, the piston and cylinderbeing arranged for actuation in forward and rearward direction with respect to one another. The cylinder is longitudinally'disposed be tween the first andfourth prop means on one side and the third and second prop means on the'opposite side, such that the cylinder is fixedly secured to the cross-portion of 3 one of the diagonal cross-elements to move the corresponding prop set while the piston rod is connected at each end with a corresponding prop means of the remaining set to move that set alternately with the movement of the cylinder.

Notably, the axis of the cylinder longitudinally bisects the cross-portions of the diagonal cross-elements and the cylinder is fixedly secured to the top side of the overlying diagonal cross-element. This is achieved by a clamp strap extending in the direction of and being substantially coextensively secured to the'cross-element top side, the clamp strap having an intermediate upward arcuate portion 'defining with the corresponding portion of the cross-element a seating channel extending in the longitudinal direction. This channel serves for receiving at least a portion of the cylinder in fixed relation thereat.

Preferably, the corresponding portion of the overlying cross-element is slightly downwardly arcuately depressed in the longitudinal direction to form a guide rail on the under side of the cross-element and in turn the corresponding portion of the cross-element underlying the overlying cross-element is also slightly downward arcuately depressed in the longitudinal direction whereby to form a corresponding guide track on the upper side thereof. In this manner, sliding abutment between the crosselements may be carried out in coacting guiding relation.

Each prop means is provided with a lower end and an upper end, the cross-elements and piston rod being connected to the prop means at the corresponding lower ends. The prop means are also each provided with an overhead supporting cap at the upper end, the supporting cap extending in longitudinal direction as well. The lower end of each prop means is provided with a prop base in which the lower end of the prop means iseffectively .seated. The prop ends of both of the prop sets are desirably displaceably seated in the corresponding prop base so that the base may execute slight pivotal displacement about the end as pivot point.

In accordance with a particular feature of the invention, the first and fourth prop means on the same side of the moving means or piston-cylinder arrangement are longitudinally interconnected at their top ends through their corresponding overhead caps by an overhead cap adjustable length linkage, while the third and second prop means on the opposite side of the moving means or piston-cylinder arrangement are also longitudinally interconnected at their top ends through their corresponding overhead caps by an overhead cap adjustable length linkage. These linkages are adjustably dimensioned for permitting the set, including the first and second prop means, to move forward in the longitudinal direction of advance while the set, including the third and fourth prop means, is stationary, so that the cap linkage between the first and fourth prop means will increase in length while the cap linkage between the third and second prop means will decrease in length. Alternately, the dimensioning is such that the set, including the third and fourth prop means, is permitted to move forward in the longitudinal direction of advance while the set, including the first and second prop means is stationary, so that the cap linkage between the first and fourth prop means will decrease in length while the cap linkage between the third and second prop means will increase in length.

More specifically, each cap linkage includes middle linkage bar means pivotally connected at each bar end to lateral linkage bar means. Each lateral linkage bar means, in turn, is separately pivotally connected to the substantially outermost point of the corresponding over-head supporting cap. The middle linkage bar means and the lateral linkage bar means permit extension and retraction in length of the corresponding linkage in longitudinal direction in coaction with the forward movement of the prop sets.

Significantly, the sum of the distances between the center point of each of the two prop means interconnected by one of the cap linkages and the respective outermost point of the corresponding overhead supporting cap therefor which is pivotally connected to the said one cap linkage is shorter than the sum of the distances between the center point of each of the remaining two prop means interconnected by the other of the cap linkages and the respective outermost point of the corresponding overhead supporting cap therefor which is pivotally connected to thesaid other cap linkage. Such shorter distance is actually shorter by an increment equal to at most the maximum amplitude stroke of the piston in the cylinder.

It is most advantageous to provide the diagonal crosselements as resilient fiat leaf spring members and to provide resilient flat leaf spring connectors between the piston rod and the corresponding prop means connected therewith, in order to provide a sufficiently resilient arrangement capable of accommodating uneven surfaces in the mine floor and mine ceiling without undue stress on the working parts.

Furthermore, prop means are provided as hydraulically operated pit prop means, i.e., hydraulic jacks, and the piston-cylinder arrangement may also be hydraulically actuated. While hydraulic fluid, such as hydraulic oil, is often used to actuate the piston-cylinder arrangement, compressed air may also be used for this purpose as is well known in the art.

The advantages of the mining prop arrangement in accordance with the invention are readily appreciated from the fact that a more uniform support of the overhead seam during the advancing of the arrangement will be achieved as well as a greater stability under load of the arrangement due to the cross-wise or diagonal connecting disposition of the props in each frame, albeit that the overlying supporting caps remain parallel to one another in the longitudinal direction of advance.

Referring to the drawing, FIG. 1 shows an advanceable -mining support arrangement with adjustable pit props for engaging the mine ceiling and mine floor, the overhead supporting caps being omitted for facility in understanding the particular construction involved. Props 1 and 2 are interconnected by means of the diagonal cross-element 6 at their bottom portions, the respective ends of the cross-element 6 actually being connected to the corresponding prop sockets 12 and 14 in which props 1 and 2 are supportingly received, respectively. In like manner, props 3 and 4 are interconnected by the diagonal crosselement 7, the cross-element 7 actually connecting the corresponding prop sockets 13 and 15 at the lower ends of the respective props and into which the lower ends of the props are supportingly received.

A piston-cylinder arrangement is used as moving means for advancing the props in the longitudinal direction including a cylinder 5 and a double-acting piston (not shown) disposed on the piston rod 11 for operable actuation within cylinder 5. The ends of piston rod 11 extend outwardly through the corresponding ends of the cylinder 5 in the well known manner. Accordingly, upon passing pressure fluid to the cylinder 5 on one side of the piston (not shown), the cylinder and piston will move relative to one another in one direction and upon passing pressure fluid to cylinder 5 on the other side of the piston (not shown) movement in the opposite direction will be achieved. Double acting piston-cylinder arrangements are well known and their operation simple. Therefore, undue description of this conventional arrangement is not necessary to a clear understanding of the inventive features of the instant arrangement.

Cross-element 6 is positioned over cross-element 7 with the cross-portions in abutting sliding relationship. The axis of cylinder 5 bisects the cross-portions of elements 6 and 7. Advantageously, a clamp strap 8 is secured onto the top surface of cross-element 6, clamp strap 8 being provided with an intermediate upward arcuate portion defining with the corresponding portion of the cross-element 6 a seating channel extending in the in fixed relation thereat.

longitudinal direction for receiving a portion of cylinder Accordingly, the correspond ing portion of the cross-element 6 is slightly downwardly arcuately depressed (see FIG. 2) in the longitudinal direction so as to form a tight fit for cylinder 5 as well as a guide rail on the under side thereof. Correspondingly, the central or cross-portion of the underlying crosselement 7 is slightly downwardly arcuately depressed in the longitudinal direction (see FIG. 2) in order to form a corresponding guide track on the upper side thereof. In this manner, the sliding abutment between the crosselements may be carried out in coacting guiding relation to preserve the longitudinal disposition of the pistoncylinder arrangement and the longitudinal forward and rearward direction of movement of the prop set including props 1 and 2, on the one hand, and the prop set including props 3 and 4, on the other hand.

While props 1 and 2 are connected with cylinder 5 for simultaneous movement therewith, by reason of the fact that their interconnecting cross-element 6 is fixedly secured to cylinder 5, in the case of props 3 and 4, the interconnecting cross-element 7 is not connected with the piston rod 11, but merely slides under cross-element 6. In order to effect the movement of props 3 and 4, resilient leaf spring connectors 9 and 10 are provided, respectively, these connectors extending transversely medially to the outer ends of piston rod 11 for connection therewith. While strap 9 extends to the corresponding end of piston rod 11 from a point close to the center of prop 3, in order to achieve a desirably large amplitude stroke for the piston rod 11, prop socket 15 for the prop 4 is rearwardly extended a desired distance, whereby connector 10 may connect prop 4 with rod 11 in a convenient way.

Of course, by providing props 1 and 2 of the first diagonal frame prop set in disengaged condition with the mine ceiling and mine floor while providing props 3 and 4 of the second diagonal frame prop set in engagement with the mine ceiling and mine floor, the first frame prop set may be advanced in the longitudinal direction by merely passsing fluid to cylinder 5. During the forward movement, diagonal cross-element 6 will slide along the guide track provided in diagonal cross-piece 7 therebelow. Assuming that this action has taken place, the props will be in the position shown in FIG. 1.

Thereafter, by placing props 1 and 2 of the first frame prop set in engagement with the 'mine ceiling and mine floor, and disengaging props 3 and 4 from engagement, props 3 and 4 may be advanced to the position shown in phantom in the direction of arrows by passing hydraulic fluid to the opposite cylinder chamber. During this time, piston rod 11 will move relative to the now stationary cylinder 5 and by reason of the connectors 9 and 10, piston rod 11 will carry forward props 3 and 4 in the desired manner. It will be appreciated that the intermediate diagonal cross-element 7 serves to provide greater stability for the diagonal frame prop set 3, i, such cross-element 7 not only improving the connection between props 3 and 4 but also stabilizing the positioning of the first prop frame set 1, 2 by reason of the abutting portions between cross-elements 6 and 7.

In accordance with the preferred embodiment, the props of at least one diagonal frame prop set are dis placeably positioned within the respective prop sockets therefor in order to permit slight pivotal displacement of the sockets about the prop bottom ends as pivot point.

As may be appreciated from FIG. 3, the diagonal crosselements 6, 7 and connectors 9, 10 are disposed at the lower end of the arrangement with cylinder 5 and piston rod 11 disposed slightly above the mine floor by reason of the dimensions of the prop sockets or bases 13, 14, for example. By making cross-elements 6, 7, and connectors or straps 9, 10 of resilient leaf spring material, unevenness in the mine floor and mine ceiling will be readily accommodated without undue stress on the working parts, and moreover, the piston-cylinder arrangement may sag slightly into contact with the floor to further provide an intermediate stabilizing support. As shown, prop 2 is directly in front of prop 4 while prop 3 is directly in front of prop 1, the positional relationship being the same as indicated in FIG. 1. The props are shown as adjustable pit props of conventional design similar to the construction of hydraulic jacks.

At the upper ends of props 2 and 3, overhead supporting caps 16 and 17, respectively, are provided, while correspondingly, at the upper ends of props 4 and 1, overhead supporting caps 18 and 19, respectively, are provided. It will be appreciated, in this connection, that while prop 2 is diagonally connected with prop 1 and prop 3 is, in turn, diagonally connected with prop 4, by reason of the crosselements 6 and 7, cap 16 of prop 2 is connected on the same side of the piston-cylinder arrangement with cap 17 of prop 3 whereas cap 18 of prop 4 is connected on the same side with cap 19 of prop 1. Hence, while diagonal connections are achieved at the bottoms of the props, parallel longitudinal connections are achieved at the tops of the props.

Specifically, the longitudinally extending prop on each side of the piston-cylinder arrangement are interconnected by an overhead cap adjustable length linkage means including a pair of parallel middle linkage bars 24, each pivotally connected at its respective ends to correspondingly positioned lateral linkage bars 24' (see FIG. 4). In turn, the outer ends of the three lateral linkage bars 24', on either side of the middle bars 24, are connected with the respective ends of the overhead supporting caps of the props. Thus, caps 16 and 17, on the one hand, and caps 18 and 19, on the other hand, may be extended and retracted advantageously, within the limits provided by the particular constructional lengths of the intermediate linkage means.

In operation, prop 2 will move longitudinally forward in the direction of arrow 25 as shown in FIG. 3 together with prop 1 diagonally positioned with respect thereto. Since the cap of prop 2 during this time would be connected with the stationary cap 17 of prop 3 on the same side of the piston-cylinder arrangement and since cap 19 of prop 1 would be connected with cap 18 of the stationary prop 4, the linkage means and cap lengths of the arrangement must be properly dimensioned in conjunction with the maximum amplitude stroke of the piston to preserve the desired functional relationship. For this purpose, the distance a between the center point of prop 4 and the outermost pivot point 22 of the corresponding cap 18 plus the distance b between the center point of prop 1 and the outermost pivot point 23 of the corresponding cap 19 must be shorter than the distance c between the center point of prop 2 and the pivot point 20 at the outermost end of cap 16 plus the distance d between the center point of the prop 3 and the outermost pivot point 21 of the corresponding cap 17. This is shown schematically in FIGURE 3 best by the distance between the pivot points 22 and 23 of caps 18 and 19, when the linkage is extended, as opposed to the distance between the pivot points 215 and 21 of caps 16 and 17 where the linkage is retracted.

Considering the illustrations of FIGURES 3 and 4, upon actuation of the piston cylinder arrangement, props 4 and 3 will be advanced in the direction of arrow 25 whereby the linkage between stationary cap 16' and advancing cap 17 will be extended while the linkage between moving cap 18 and stationary cap 19 will be retracted.

Such retraction is limited by the distance apart of pivot points 22 and 23, since a short distance apartwill necessitate short strokes of the piston cylinder arrangement or else the outer end of cap 18 will abut against the co r V other hand, as aforesaid, due to the shorter distance a and b, the corresponding ends of caps 18 and 19 will not undesirably abut one another, so long as the stroke amplitude of the piston-cylinder arrangement is adjusted accordingly.

Considering the over-all operation of conventional mining frame arrangements as contrasted with the arrangement in accordance with the invention, FIG. illustrates that the frame pairs used in the prior art were positioned for parallel movement with the piston attached to one frame unit and the cylinder attached to the other frame unit. Thus, the left-hand side frame unit had to be disengaged from the mine ceiling and mine floor for advancing, and upon engagement with the mine ceiling and mine floor, the right-hand frame unit could be disengaged for advancement in its turn. However, either the left side or the right side of each frame arrangement had to be disengaged for advancement leaving more than one-half of the surface area to be supported in a condition of non-support.

Turning to FIGURE 6, a similar plurality of frame units is provided, but in this case the overhead caps are movable in accordance with the invention. Thus, the forward left-hand side cap moves simultaneously with the rearward right-hand side cap along the line of units so that a greater degree of distribution of the support will be achieved in an even manner. Considering the weight of the overhead seam to be supported, the type of operations involved, the size of the mining equipment, the area occupied by each frame unit, and the actual area supported when one or both frame units are in engagement with the mine ceiling as opposed to the entire surface of the mine ceiling, the advantages of the diagonal frame positioning of the invention become apparent.

Clearly, the unsupported surfaces of the overhead seam are diminished by at least one-half during the advancing of either of the frames, in accordance with the invention, since these frames are diagonally interconnected. While a certain portion of the support of the overhead seam is lacking on both sides of the arrangement during the advancing operation, this is compensated for by the advantage of a more uniform support for the overhead seam. Of course, by reason of the diagonal interconnections between the props to form the diagonal frames and the manner in which these frames are attached to the longitudinally extending piston-cylinder arrangement, an enlarged stability under load of the entire arrangement is assured while the overhead caps are maintained in parallel relation in the longitudinal direction. As aforesaid, the length of the caps measured from the center point of the respective prop to the outermost point of the cap where the linkage or hinged joint is connected should be smaller in total than the combined lengths between the center points of the props on the opposite side of the piston-cylinder arrangement and the outermost pivot points therefor for connecting the linkage or hinged joint means. The increments of shortness as aforesaid are measured by the length of the stroke of the piston cylinder arrangement in operation to provide an unobstructed increment of advance of one diagonal frame followed by the other.

It will be appreciated that by reason of the linkage means 24, 24, the difference in length occasioned by the lowering of the caps out of engagement with the mine ceiling is generally offset. While this is especially true with respect to the longer distance cap linkage in both positions and to the shorter distance cap linkage in re tracted position, a different situation obtains where the shorter distance cap linkage is in extended position. In the latter instance, since one of the caps is stationary vand in engagement with the mine ceiling while the cap measured by the outermost pivot point of the stationary cap and the outermost pivot point of the cap being lowered from engagement. In accordance with the invention, the proper distance measured between the two pivot points may be effectively maintained without any prop tilting where the shorter distance cap linkage means are in maximum extended position, by providing each of the shorter distance caps, preferably, with a wide cap socket into which the corresponding prop head is situated in a displaceable manner.

Specifically, where prop 1 is stationary and the linkage is in maximum extended position with respect to prop 4 which is released from engagement with the mine ceiling, the distance between pivot 23 and pivot 22 may be maintained, with the multiple joint 24, 24' in such extended position describing a circle about point 23 as center, without any tilting, by constructionally providing the upper ends of the props 1, 4 with spherical heads for engaging corresponding spherical sockets in the respective caps, the diameter of the spherical prop heads being slightly less than the diameter of the corresponding spherical cap sockets. In this manner, a slight displacement of the caps on the respective props may take place in the direction of advance, i.e., as, for example, is Shown by arrow 25, so that the maximum limit of the multiple joint in extended position is compensated sufiiciently to prevent undesired tilting of the props.

In the case of shorter cap 18, therefore, while prop 4 may be lowered, cap 18 will be displaced both in downward direction with prop 4 and in forward direction on the prop head to maintain the fixed distance between pivot point 22 of cap 18 and pivot point 23 of cap 19 via linkage 24, 24'. The opposite action will take place where prop 4 is stationary and prop 1 is released for advance.

This provision for slight displacement between the props and the corresponding caps does not alter in any way the desired overhead support of the mine ceiling in view of the over-all arrangement in accordance with the invention, but, in fact, avoids a loss of support which might otherwise be occasioned by the tilting of the props out of their normal spherical position.

Nevertheless, it should be noted that the lower ends of the props 1, 2, 3, 4 may be movably inserted, in the usual way, in the bottom sockets or bases 12, 13, 14, 15 to permit a desired degree of displacement to prevent undue stress on the working parts by unevenness in the mine fioor.

What is claimed is:

1. Advanceable mining support arrangement with adjustable pit prop means for engaging the mine ceiling and mine floor, which comprises moving means having a forward and a rearward end and including a double-acting piston-cylinder arrangement, first prop means positioned adjacent said forward end on one side of said moving means and second prop means positioned adjacent said rearward end on the opposite side of said moving means, said first and second prop means together forming a prop set and being connected with the piston of said moving means for simultaneous forward and rearward movement, and third prop means positioned adjacent said forward end on said opposite side of the moving means and fourth prop means positioned adjacent said rearward end on said one side of said moving means, said third and fourth prop means together forming a prop set and being connected with the cylinder of said moving means for simultaneous forward and rearward movement alternately with the movement of said first and second prop means.

2. Arrangement according to claim 1 wherein the prop means of one set are interconnected by a first diagonal cross-element and the props of the other set are interconnected by a second diagonal cross-element overlying the first cross-element, the adjacent cross-portions of said cross-elements being in sliding abutment with each other.

3. Arrangement according to claim 2 wherein said piston-cylinder arrangement includes a double-ended cylinder and a double-ended piston rod extending through the corresponding ends of the cylinder, said piston and cylinder being arranged for actuation in forward and rearward direction with respect to one another, said cylinder being longitudinally disposed between'said first and fourth prop means on one sideand said third and second prop means on the opposite side, and said cylinder being fixedly secured to the cross-portion of one of said diagonal crosselements to move the corresponding prop set while said piston rod is connected at each end with a corresponding prop means of the remaining set to move said set alternately with the movement of the cylinder.

'4. Arrangement according to claim 3 wherein the axis of said cylinder longitudinally bisects the cross-portions of said diagonal cross-elements, said cylinder being fixedly secured to the top side of the overlying diagonal crosselement by a clamp strap extending in the direction of and being substantially coextensively secured to said crosselement, said clamp strap having an intermediate upward arcuate portion defining with the corresponding portion of the cross-element a seating channel extending in the longitudinal direction for receiving at least a portion of said cylinder in fixed relation thereat.

5. Arrangement according to claim 4 wherein the said corresponding portion of the overlying cross-element is slightly downwardly arcuately depressed in said longitudinal direction to form a guide rail on the under side of said cross-element and in turn the corresponding portion of the cross-element underlying said overlying crosselement is also slightly downwardly arcuately depressed in said longitudinal direction to form a corresponding guide track on the upper side thereof, whereby the sliding abutment between said cross-elements may be carried out in coacting guiding relation.

6. Arrangement according to claim 5 wherein each prop means has a lower end an an upper end, the crosselements and piston rod being connected to said prop means at the corresponding lower ends, and said prop means each being provided with an overhead supporting cap at the upper end.

7. Arrangement according to claim 6 wherein said prop means are each provided with a prop socket in which the lower end of the prop means is removably seated, said caps each having a cap socket and the upper end of each prop means having a'cap head, the width of said cap socket being slightly greater than the width of the cap head therefor, whereby said cap may be displaced slightly in the longitudinal direction with respect to the prop means therefor.

8. Arrangement according to claim 7 wherein the first and fourth prop means on the same side of said moving means are longitudinally interconnected at their upper ends through their corresponding overhead caps by an overhead cap adjustable length linkage and the third and second prop means on the opposite side of said moving means are longitudinally interconnected at their upper ends through their corresponding overhead caps by an overhead cap adjustable length linkage, said linkages being adjustably dimensioned for permitting the set including the first and second prop means to move forward in the longitudinal direction of advance While the set including the third and fourth prop means is stationary so that the cap linkage between the first and fourth prop means will increase in length while the cap linkage between the third and second prop means will decrease in length, and alternately for permitting the set including the third and fourth prop means to move forward in longitudinal direction of advance while the set including the first and second prop means is stationary so that the cap linkage between the first and fourth prop means will decrease in length v while the cap linkage between the third and second prop means will increase in length.

9. Arrangement according to claim 8 wherein each said cap linkage'includes middle linkage bar means pivotally connected at each bar end to lateral linkage bar means, each said lateral linkage bar means being sepai'ately pivotally connected in turn to the substantially outermost point of the corresponding overhead supporting cap, for extension and retraction in length of the corresponding linkage in longitudinal direction in coaction with the forward movement of the prop sets.

10. Arrangement according to claim 9 wherein the sum of the distances between the center point of each of the two prop means interconnected by one of the cap linkages and the respective outermost point of the corresponding overhead supporting cap therefor which is pivotally connected to the said one cap linkage is shorter than the sum of the distances between the center point of each of the remaining two prop means interconnected by the other of the cap linkages and the respective outermost point of the corresponding overhead supporting cap therefor which is pivotally connected to the said other cap linkage, such shorter distance being shorter by an increment equal to at least the maximum amplitude stroke of the piston in the said cylinder.

11. Arrangement according to claim 10 wherein said diagonal cross-elements are resilient flat leaf spring members, said piston rod being resiliently connected with the corresponding prop means therefor by resilient flat leaf spring connectors, and said prop means being hydraulic pit prop means.

12. Advanceable mining support arrangement with adjustable height pit props for engaging the mine ceiling and mine floor, which comprises longitudinally extending motor means including a cylinder having a forward and a rearward end, a double acting piston mounted on a piston rod operably disposed in said cylinder for relative forward and rearward movement, said rod having ends extending through the corresponding ends of the cylinder, four pit props, each having an overhead supporting cap, said props including first and fourth props positioned as a pair in tandem on one longitudinal side of said cylinder and third and second props positioned as a pair in tandem on the other longitudinal side of said cylinder, said first and fourth prop pair being longitudinally parallel to said third and second prop pair and both said pairs being parallel to said cylinder and rod, said first prop being positioned adjacent said forward end and said second prop being positioned adjacent said rearward end and being interconnected by a first resilient flat leaf spring diagonal cross-element with the cylinder to form a first prop set for simultaneous forward and rearward movement with the movement of said cylinder, correspondingly said third prop means being positioned adjacent said forward end and said fourth prop being positioned adjacent said rearward end and being interconnected by a second resilient fiat leaf spring diagonal cross-element to form a second prop set, said second cross-element extending cross-wise underneath the first cross-element in sliding engagarnent therewith, said third and fourth props each being connected to a corresponding end of. said rod by a transversely medially extending resilient flat leaf spring connector for simultaneous forward and rearward movement of said second prop set with the movement of said rod alternately with the movement of said first prop set together with the movement of said cylinder, the axis of said cylinder longitudinally bisecting the cross-portions of said cross-elements, a clamp strap extending in the direction of and being substantially coextensively secured onto the upper side of the first cross-element, said strap having an intermediate upward arcuate portion defining with a corresponding portion of said first cross-element a seating channel extending in the longitudinal direction receiving partly and fixedly securing therewithin said cylinder, said corresponding portion of the first cross-elernent being slightly downwardly arcuately depressed in said longitudinal direction to form a guide rail on the under side of said first cross-element and in turn the corresponding portion of the second cross-element thereunder being also slightly arcuately depressed in said longitudinal direction to form a corresponding guide track on the upper side thereof, whereby sliding abutment between said crosselements may be carried out in coacting guiding relation, the first and fourth props being longitudinally interconnected at their upper ends through their corresponding overhead caps by an adjustable length first linkage and the third and second props being longitudinally interconnected at their upper ends through their corresponding overhead caps by an adjustable length second linkage, said linkages being adjustably dimensioned for permitting the set including the first and second props to move forward in the longitudinal direction of advance while the set including the third and fourth props is stationary so that the first linkage between the first and fourth props will increase in length While the second linkage between the third and second props will decrease in length and alternately for permitting the set including the third and fourth props to move forward in the longitudinal direction of advance while the set including the first and second props is stationary so that the first linkage between the first and fourth props will decrease in length while the second linkage between the third and second props will increase in length.

13. Arrangement according to claim 12 wherein each said cap linkage includes middle linkage bar means pivotally connected at each bar end to lateral linkage bar means, each said lateral linkage bar means being separately pivotally connected in turn to the substantially outermost point of the corresponding overhead supporting cap, for extension and retraction in length of the corresponding linkage in longitudinal direction in coaction with the forward movement of the prop sets.

14. Arrangement according to claim 13 wherein the sum of the distances between the center point of each of the two props interconnected by said first linkage and the respective outermost point of the corresponding cap therefor which is pivotally connected to said first linkage is shorter than the sum of the distances between the center point of each of the remaining two props interconnected by said second linkage and the outermost point of the corresponding cap therefor which is pivotally connected to said second linkage, by an increment equal to the amplitude stroke of the piston in the said cylinder.

15. Arrangement according to claim 14 wherein each said prop is provided at its upper end with a cap head and each said overhead cap is provided with a cap socket, the width of said socket being greater than the width of said head, whereby longitudinal displacement of each said cap with respect to the corresponding prop may take place when one cap is lowered from engagement with the mine ceiling while the cap linkably connected therewith remains in engagement with the mine ceiling, and each said prop having at its lower end a base socket, the lower end of the prop being movably inserted in the base socket.

References Cited by the Examiner FOREIGN PATENTS 1,229,479 3/60 France.

EARL J. WITMER, Primary Examiner.

JACOB L. NACKENOFF, Examiner.

Claims (1)

1. ADVANCEABLE MINING SUPPORT ARRANGEMENT WITH ADJUSTABLE PIT PROP MEANS FOR ENGAGING THE MINE CEILING AND MINE FLOOR, WHICH COMPRISES MOVING MEANS HAVING A FORWARD AND A REARWARD END AND INCLUDING A DOUBLE-ACTING PISTON-CYLINDER ARRANGEMENT, FIRST PROP MEANS POSITIONED ADJACENT SAID FORWARD END ON ONE SIDE OF SAID MOVING MEANS AND SECOND PROP MEANS POSITIONED ADJACENT SAID REARWARD END ON THE OPPOSITE SIDE OF SAID MOVING MEANS, SAID FIRST AND SECOND PROP MEANS TOGETHER FORMING A PROP SET AND BEING CONNECTED WITH THE PISTON OF SAID MOVING MEANS FOR SIMULTANEOUS FORWARD AND REARWARD MOVEMENT, AND THIRD PROP MEANS POSITIONED ADJACAENT SAID FORWARD END ON SAID OPPOSITE SIDE OF THE MOVING MEANS AND FOURTH PROP MEANS POSITIONED ADJACENT SAID REARWARD END OF SAID ONE SIDE OF SAID MOVING MEANS, SAID THIRD AND FOURTH PROP MEANS TOGETHER FORMING A PROP SET AND BEING CONNECTED WITH THE CYLINDER OF SAID MOVING MEANS FOR SIMULATANEOUS FORWARD AND REARWARD MOVEMENT ALTERNATELY WITH THE MOVEMENT OF SAID FIRST AND SECOND PROP MEANS.

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