1. Field of the Invention
This invention relates to a truss shoe with a wedge retaining sleeve, and more particularly, to a truss shoe having a wedge retaining sleeve, or locking tube to detachably secure a cable retention assembly in the passageway of a cable receiving section of the truss shoe.
2. Discussion of the Presently Available Technology
Truss-type mine roof supports are well known in the art of supporting the roof of an underground passageway, such as a mine passage. A basic truss system includes one or more rods extending horizontally the width of the mine passage adjacent the roof and connected at their ends to anchor bolts, which extend at an angle adjacent the ribs of the passage into the rock strata over a solid pillar. The rods are tensioned and vertical components of compressive forces are transmitted into the solid material over the pillars, as opposed to the unsupported rock material immediately above the passage.
With this arrangement, a truss system shifts the weight of the rock strata from over the mined-out passage back onto the pillars. Conventionally, holes are drilled into the mine roof at a 45° angle from the horizontal adjacent to the mine rib so that the holes extend into the supported rock structure over a pillar.
Once the holes are drilled at an angle into the strata over the pillars at the rib line, anchor bolts are inserted into the drilled holes and are secured in place using mechanical expansion shell assemblies and/or a resin made from a mixture of a resin component and an epoxy component. Before the bolts are inserted in the drilled holes, truss shoes or bearing blocks are positioned on the bolt at the emergent end of the bolt from the hole. As the bolts are securely anchored in the drilled holes, the bearing surfaces of the truss shoes or bearing blocks are compressed into engagement with the mine roof.
For an uneven mine roof or a roof having severely potted areas, the truss shoe preferably has sufficient bearing surface to contact the mine roof so that the truss shoe is correctly positioned for engagement with the horizontal truss members. Once the truss shoes are securely positioned at the mine roof adjacent the ribs, the horizontal truss members are assembled and connected to the truss shoes. The truss members are tightened to a preselected load to exert tension on the truss members so that the weight of the rock strata over the mined out area beneath the roof is shifted along the horizontal truss members upwardly into the solid rock strata over the pillars at the rib line.
The truss hardware is connected under tension to the truss shoes that are held tightly against the mine roof by the anchored angle bolts. A wide variety of truss hardware is commercially available to form a truss system between the anchored angle bolts. For example and not limiting to the discussion, U.S. Pat. No. 7,261,494 (hereinafter also referred to as “USPN '494”) to the Jennmar Corporation discloses a cable truss system including a pair of truss shoes, a pair of inclined bolts, and a truss assembly. Each truss shoe attaches to a roof through an inclined bolt and includes a surface for contacting the roof and a truss supporting member. The truss assembly extends between the truss supporting members of the pair of truss shoes for applying an uplifting force to the roof to support the roof above the passage. The truss assembly includes a pair of cables engaged to the truss shoes attached to the roof.
Several non-limiting embodiments of truss shoes are disclosed in USPN '404. Of particular interest in this discussion is the truss shoes shown in FIGS. 15-18 of USPN '404. In general, the truss shoe includes a bolt receiving end portion to receive the bolt that attaches the truss shoe to the roof and an opposite cable receiving and retaining end portion to receive an end of a cable and to secure the cable to the truss shoe. The cable receiving and retaining end portion includes a tapered passageway for receiving a wedge or cone-shaped retention assembly. The retention assembly has three pieces held together by a flexible band and has an expander to bias the pieces away from one another to pass a cable into an end of the retention assembly.
The retention assembly having the expander is placed in the passageway of the assembly and secured in the passageway by a washer. More particularly, the bottom portion of the washer is placed in a groove formed in the shoe, and the upper portion of the washer is secured in position by a tab bent over the top of the washer. In the event the expander moves out of the retention assembly during the handling and shipping of the truss shoe, or it is necessary or desired to remove the retention assembly from the passageway of the truss shoe, the washer is removed by lifting the tab and lifting the washer from the groove in the truss shoe. After a retention assembly is placed in the passageway, the washer is secured over the passageway as previously discussed.
Although the truss shoes of USPN '494 discussed above are acceptable, there are limitations. More particularly, bending the tab toward or away from the top of the washer causes fatigue of the tab, and the tab brakes from the truss shoe. When the tab breaks from the truss shoe, the washer is usually secured in position by welding the top of the washer to the truss shoe. As is appreciated by those skilled in the art, breaking the weld to release the washer from, and welding the washer to, the truss shoe is time consuming.
As can be appreciated by those skilled in the art, it would be advantageous to provide an arrangement for securing the cable retention assembly in, and for removing the cable retention assembly from, the passageway of the cable receiving section of a truss shoe that does not have the limitations of the presently available arrangements, e.g. the washer and tab or weld arrangement discussed above.
This invention relates to a truss shoe for use in a mine roof support system. The truss shoe includes, among other things, a one-piece body member having a base member having a bearing surface; a bolt receiving section opposite to the bearing surface and extending upward from the base member, the bolt receiving section including a bore extending through the bolt receiving section and the base member; a cable engaging section opposite to the bearing surface and extending upward from the base member and spaced from the bolt receiving section. The cable engaging section has a passageway therethrough, the passageway having a first open end spaced from, and in facing relationship, to the bolt receiving section and an opposite second end, wherein the passageway has a cone-shaped portion having a decreasing diameter as the distance from the first end of the passageway increases, and an intermediate section opposite to the bearing surface and between the bolt receiving section and the cable receiving section, the intermediate section including a cut out in base of the intermediate portion, the cut out portion extending from the first open end of the passageway toward the bolt receiving section and terminating at a riser.
This invention further relates to a truss shoe for use in a mine roof support system including, among other things, a one-piece body member, having a base member including a bearing surface for engaging a mine roof; a bolt receiving section extending upward from the base member, the bolt receiving section including a bore hole extending through the bolt receiving section and the base member, wherein the bore hole of the bolt receiving section has a first end opening at the bearing surface that is non-circular and an opposite second end opening that is circular. The shoe further includes a cable engaging section spaced from the bolt receiving section, the cable receiving section having a passageway therethrough to receive a portion of a cable. The cable engaging section includes a housing extending upward from the base member and having a first open end facing the bolt receiving section and an opposite second open end, with the passageway between the first end and the second end. The passageway has decreasing distance between wall portions as the distance from the first open end increases to provide a passageway having a predetermined interior surface configuration. The shoe further includes an intermediate section between the bolt receiving section and the cable engaging section, the intermediate section including a pair of spaced ribs between and interconnecting the bolt receiving section and the cable engaging section, and a cut out groove between the ribs. A wedge assembly including at least two parts is mounted in the passageway; an expander mounted in the wedge assembly, and a locking tube having a first end and an opposite sloped second end, the locking tube mounted in the cut out groove, to prevent the wedge assembly from moving out of the first open end of the passageway, wherein the locking tube has an inside diameter and outside diameter sized to retain the wedge assembly in the passageway while allowing the expander to pass through the locking tube.
This invention still further relates to a method of securing a cable in a truss shoe of a mine roof support assembly by, among other things, providing a truss shoe having a one-piece body member including base member having a bearing surface, an opposite surface having a bolt receiving section and a housing spaced from the bolt receiving section. The bolt receiving section has a bore terminating at the bearing surface to provide a hole in the bearing surface. The method further includes inserting a wedge assembly in the passageway of the housing providing a locking tube having a first end, a second end and a longitudinal axis extending from the first end to the second end of the locking tube, wherein the second end of the locking tube lies in a plane generally normal to the longitudinal axis of the locking tube and the second end of the locking tube lies in a plane that subtends an acute angle with the longitudinal axis of the locking tube. The first end of the locking tube is inserted in the passageway with the sloped end in facing relationship to the base member, and rotating the locking member to move the second end of the locking tube into engagement with a riser in the base member to secure the end of the locking tube in the passageway and to prevent the wedge assembly from moving out of the passageway.
A complete understanding of the invention will be obtained from the following description when taken in connection with the accompanying drawing figures wherein, unless indicated otherwise, like reference characters identify like parts throughout. Further, the terminology used herein to discuss the non-limiting embodiments of the invention is for purposes of description and not of limitation.
For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, and derivatives thereof, shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention can assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary non-limiting embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, and so forth, used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims can vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between and inclusive of the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 1 to 6.7, or 3.2 to 8.1, or 5.5 to 10.
Referring to
As is appreciated, the truss system incorporating features of the invention is not limited to providing an uplifting force to the roof of a passageway, e.g. the passageway 14 can be used to apply a supporting force to the walls of the passageway, e.g. the sidewalls 18 and 20.
The truss system 10 is secured to the mine roof 12 by elongated roof bolt assemblies 28 inserted in bore holes 29 drilled at an angle through the surface of the roof 12 for a predetermined length into the rock formation 16 which is supported by the solid pillars or ribs 22 and 24. In one non-limiting embodiment of the invention, the bore holes 29 are drilled at a 45° angle for a distance of six feet (1.8 meters) or greater into the rock formation 16 spaced within two feet (0.6 meters) from the respective side walls 18 and 20 to end points supported by solid material above the pillars 22 and 24.
One non-limiting roof bolt assembly, e.g., roof bolt assembly 28, that can be used in the practice of the invention and not limiting the invention thereto, includes an elongated roof bolt, e.g., the elongated roof bolt 31, having an enlarged head 33 at one end portion 34, a washer 36 between the enlarged head 33 of the roof bolt 31 and the truss shoe 27, and an opposite threaded end portion 38. A mechanical expansion shell assembly 40 is threadably engaged to the threaded end portion 38 of the bolt 31. As is well known in the art, upon rotation of the roof bolt 31, the shell assembly 40 is expanded into gripping engagement with the wall of the bore hole 29 to exert tension on the elongated roof bolt 31, with the end portion 34 of the bolt 31 bearing against the mine roof 12. To increase the anchorage of the elongated roof bolt 31 of the roof bolt assembly 28 within the bore hole 29, resin can be used in combination with the roof bolt assembly 28 when it is installed, e.g. but not limiting to the invention, as disclosed in U.S. Pat. No. 6,619,888 (hereinafter “USPN '888), which patent is hereby incorporated by reference. The use of resin adds additional strength to the anchorage of the roof bolt 31 of the roof bolt assembly 28 in its respective one of the bore holes 29 when torque is applied to the end portion 34 of the roof bolt 31.
With continued reference to
With reference to
Prior to installation of the elongated roof bolt assembly 28 in the bore hole 29 in the rock formation 16, the end portion 38 of the roof bolt 31 is moved through bore hole 76 in the bolt receiving section 64 of the truss shoe 27 with the enlarged head 33 of the roof bolt 31 and the washer 36 engaging open end 78 of the bore hole 76 of the truss shoe 27. The expansion shell assembly 40 can be threaded onto the threaded end portion 38 of the roof bolt 31 before the roof bolt 31 is moved through the bore hole 76 of the truss shoe 27, or after the roof bolt 41 is moved through the bore hole 76 of the truss shoe 27. The roof bolt 31 having the expansion shell assembly 40 is then inserted upwardly into the angled bore hole 29 in the rock formation 16. The roof bolt assembly 28 is advanced into the bore hole 29 so that the enlarged head 33 moves the washer 36 against the open end 78 of the bore hole 76 of the truss shoe 27 to urge the bearing surface 62 of the truss shoe 27 (see
As can be appreciated, the invention is not limited to the manner in which the truss shoe of the invention is secured against the roof 12 of the passageway 14 (see
With continued reference to
With reference to
With continued reference to
The first circular portion 100 at the first open end 96 of the passageway 94 has a constant diameter for a given distance, and the diameter is sized to receive end 108 of locking tube or wedge retaining sleeve 110 (see
With reference to
Optionally inner surfaces 124 of the passageway 118 of the cable retainer 116 can be provided with a rough surface, e.g. and not limiting to the invention, with teeth 132 (shown only in
In one non-limiting embodiment of the invention, the diameter of the second circular portion 106 of the passageway 94 of the housing 90 of the truss shoe 27 (see
In one non-limiting embodiment of the invention, the length of the cable retaining assembly 114 is 1.6 inches (4.1 centimeters). Preferable the length of the first cone-shaped portion 102 of the passageway 94 of the housing 90 is greater than the length of the cable retention assembly 114 as measured between the ends 128 and 138 of the cable retention assembly 114. With this arrangement, the cable retention assembly 114 can move toward the first circular portion 100 of the passageway 94 to provide the segments 120 of the cable retention assembly 124 room to expand as the cable end 48 is moved into the passageway 118 of the cable retention assembly 114 to move the expander 136 out of the passageway 118. After the expander 136 is moved out of the passageway 118, the cable 42 is pulled away from the truss shoe 27 to move the cable retention assembly 114 toward the second circular portion to move the segments 120 of the cable retainer 116 toward one another to bias the friction surface 132 against the outer surface 134 of the cable 42 to secure the cable 42 in the housing 90 of the truss shoe 27. In one non-limiting embodiment of the invention, the length of the first cone-shaped portion 102 of the passageway 94 is 2 inches (5.1 centimeters), and the length of the passageway 118 of the cable retention assembly 114 as measured between the ends 128 and 138 of the cable retention assembly 114 is 1 9/16 inches (4 centimeters).
With reference to
In general, the locking tube 110 is locked, or secured, or detachably secured, in position by inserting the end 108 of the locking tube 110 into the first circular portion 100 of the passageway 94 and rotating the locking tube to move end portion 148 of the end 144 of the locking tube 110 into engagement with a riser 152 below the open end 78 of the bore hole 76 of the truss shoe 27 (see
As can now be appreciated, the invention is not limited to the height of the riser 152 and the length of the cut out 150. To prevent the end portion 148 of the end 144 of the locking tube 110 from moving above the riser when the truss shoe is handled, the height of the riser preferable is made higher as the difference between the outside diameter of the end 108 of the locking tube 110 and the diameter of the first circular portion 100 increases and/or the length of the locking tube increases.
With reference to
In general, the truss system 10 using the truss shoe 27 of the invention is assembled in the following manner. The cable retention assembly 114 having the expander 136 is captured in the first cone-shaped passageway 102 of the cable receiving section 66 of the truss shoe 27, and the bolt receiving section 64 of the truss shoe 27 is bolted to the roof 12 of the underground passageway 14, as previously discussed. With reference to
The locking tube 110 retains the cable retaining assembly 114 in the passageway 94 of the housing 90 of the cable engaging section 66 of the truss shoe 27. After the cable end 58 has moved through the cable retention assembly 114, the cable 42 is pulled away from the second open end 98 of the passageway 94 to secure the cable 56 in the cable retention assembly 114, which is secured in the first cone-shaped portion 102 of the passageway 94 of the truss shoe 27. The opposite end of the cable end 44 is secured to the coupler 46 (see
As can now be appreciated, the cable retention assembly 114 can be removed from the first cone-shaped portion 102 of the passageway 94 by rotating the locking tube 110 180° to move the end portion 148 of the locking tube 110 away from the riser 152 and to position the slope end 144 of the locking tube 110 in spaced facing relationship to the cutout 150 (see
As can now be appreciated, outer surface of the locking tube 110 can be provided with a rough surface, e.g. but not limiting to the invention, ribs 156 (only two shown in
In the preferred embodiment of the invention, the truss shoe 27 having the base 60, the bolt receiving section 64, the intermediate section 68, and the cable engaging section 66 is a formed, one-piece truss shoe 27 (see
As can be appreciated, the invention is not limited to the dimensions of the truss shoe 27 of the invention, and the truss shoe should be large enough to provide a bearing surface 62 having an area sufficient to span recesses in the roof 12 (see
With reference to
As can now be appreciated, the invention is not limited to the shape or the dimensions of the side ribs 70 and 72, however, the side ribs 70 and 72 should be sized to provide structural stability to the truss shoe, for example and not limiting to the invention to prevent bending of the truss shoe at a position between the bolt receiving section 64 and the cable engaging section 66 (see
It will be understood by those skilled in the art that while the foregoing description set forth in the detailed non-limiting preferred embodiments of the present invention, modifications, additions, and changes can be made thereto without departing from the spirit and scope of the invention.
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Number | Date | Country | |
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20100310325 A1 | Dec 2010 | US |