Patent Publication Number: US-2015086280-A1

Title: Roof support sheet handling for underground mines

Description:
RELATED APPLICATIONS 
     This application is a divisional application of U.S. application Ser. No. 13/399,495, filed Feb. 17, 2012, which claims priority to U.S. Provisional Application No. 61/444,599 filed Feb. 18, 2011, the entire contents of which are both hereby incorporated by reference. 
    
    
     BACKGROUND 
     Embodiments of the invention relate to mesh handling systems for underground mines and bolting machines. 
     SUMMARY 
     Large roof support sheets (e.g., steel mesh sheets) are commonly bolted to the overhead surfaces of a mined tunnel (hereinafter referred to as “roofs”) to increase personnel safety. The sheets, however, are unwieldy, which makes them difficult to move and position for bolting. 
     Therefore, embodiments of the invention provide systems for installing roof support sheets on a mine roof. One system includes a support frame, a lifting system, and a feeding system. The support frame holds a plurality of roof support sheets to be installed on a mine roof. The lifting system lifts at least one of the plurality of roof support sheets from the support frame. The feeding system obtains the at least one of the plurality of roof support sheets from the lifting system and feeding the at least one of the plurality of roof support sheets toward an installation apparatus for installation on the mine roof 
     Another embodiment of the invention provides a lifting system for installing roof support sheets on a mine roof. The lifting system includes a shoe and at least one arm. The shoe engages a roof support sheet contained in a support frame. The at least one arm moves the shoe to engage the roof support sheet and, after the shoe is engaged with the roof support sheet, moves the roof support sheet toward an installation apparatus for installing the roof support sheet on the roof mine. 
     Yet another embodiment of the invention provides a feeding system for installing roof support sheets on a mine roof. The feeding system includes a drive assembly and a support. The drive assembly engages a roof support sheet and moves the roof support sheet toward an installation apparatus, and the support supports the roof support sheet moved by the drive assembly. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a bolting and mining machine according to one embodiment of the invention. 
         FIG. 2   a  is a top view of the bolting and mining machine of  FIG. 1  illustrating a lifting system and a feeding system according to one embodiment of the invention. 
         FIG. 2   b  is a side view of the lifting system and the feeding system of  FIG. 2   a.    
         FIG. 2   c  is a cross-sectional view of the lifting system of  FIG. 2   b  taken along line A-A. 
         FIG. 2   d  is a cross-sectional view of the feeding system of  FIG. 2   b  taken along line B-B. 
         FIG. 3  is a perspective view of the lifting system of  FIG. 2   a.    
         FIG. 4   a  is a top view of the lifting system of  FIG. 2   a.    
         FIG. 4   b  is a side view of the lifting system of  FIG. 2   a  in a raised and extended position. 
         FIG. 5  is a perspective view of a shoe included in the lifting system of  FIG. 2   a  according to one embodiment of the invention. 
         FIGS. 6   a  through  6   e  illustrate the shoe of  FIG. 5  lifting a roof support sheet according to one embodiment of the invention. 
         FIGS. 7   a  through  7   e  illustrate a gripper arrangement included in the lifting system of  FIG. 2   a  lifting a roof support sheet according to one embodiment of the invention. 
         FIGS. 8 and 9   a  are perspective views of the feeding system of  FIG. 2   a  according to one embodiment of the invention. 
         FIG. 9   b  is side view of the feeding system of  FIG. 8  including a table and a sprocket assembly, with the table and the sprocket assembly shown in a “down” position according to one embodiment of the invention. 
         FIG. 9   c  is a side view of the feeding system of  FIG. 8 , with the sprocket assembly shown in an “up” position according to one embodiment of the invention. 
         FIG. 9   d  is a side view of the feeding system of  FIG. 8 , with the table shown in an “up” position according to one embodiment of the invention. 
         FIGS. 10   a  through  10   e  illustrate a single sprocket arrangement for the feeding system of  FIG. 2   a.    
         FIGS. 11 and 12  illustrate multiple sprocket arrangements for the feeding system of  FIG. 2   a.    
         FIGS. 13-16  illustrate alternative feeding systems according to various embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. 
     Also, although directional references, such as upper, lower, downward, upward, rearward, bottom, front, rear, etc., may be made herein in describing the drawings, these references are made relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form. In addition, terms such as “first,” “second,” and “third” are used herein for purposes of description and are not intended to indicate or imply relative importance, significance, or ordering unless otherwise indicated. 
     As described above, handling large roof support sheets in an underground mine can be a difficult process and, if performed incorrectly, can create safety concerns. Accordingly, embodiments of the invention provide systems and methods for lifting and conveying roof support sheets, such that they can be positioned for installation.  FIG. 1  is a perspective view of a machine  10  according to one embodiment of the invention. As shown in  FIG. 1 , the machine  10  includes a support frame  12  that has a first end  12   a  and a second end  12   b.  The support frame  12  can be raised and lowered (e.g., using one or more hydraulic systems). The support frame  12  holds one or more roof support sheets  13 . The roof support sheets  13  can include steel mesh sheets or can be constructed from another metal or another material capable of supporting a mine roof. In some embodiments, multiple sheets  13  (e.g., approximately 30 sheets) are formed into a pod  14  and placed within the support frame  12 . The pod  14  can include a container (e.g., see  FIG. 6   a ) that holds multiple sheets  13 , which makes it easier to load sheets  13  into the support frame  12 . As shown in  FIG. 1 , the sheets  13  can be positioned on the support frame  12  length-wise along the length of the machine  10  (e.g., parallel to the direction of travel of the machine  10  in a longitudinal position). Positioning the sheets  13  in this orientation keeps the width of the machine  10  reduced, which allows for easier maneuverability of the machine  10  in a mine. 
     Positioned in front of the second end  12   b  of the support frame  12  is installation apparatus  15  for positioning a sheet  13  on the mine roof and bolting the sheet  13  to the roof. The installation apparatus  15  can include a positioning frame or platform  16 . The positioning frame  16  can have a “T-shape” and can hold one or more sheets  13  for installation on a mine roof. In particular, in some embodiments, the positioning frame  16  holds one sheet  13  at a time length-wise across the upper part of the “T-shape” (e.g., perpendicular to the direction of travel of the machine  10  in a transverse position), and the positioning frame  16  (or portions thereof) raises and lowers (e.g., using one or more hydraulic systems) the sheet  13  to position the sheet  13  along the mine roof. In some embodiments, the positioning frame  16  can also move forward and backward (e.g., parallel to the direction of travel of the machine  10 ) to properly position a sheet  13  along the mine roof. In some embodiments, the positioning frame  16  lifts and positions a new sheet  13  such that an edge of the new sheet  13  overlaps with the end of the previously-bolted sheet  13 . As shown in  FIG. 1 , the installation apparatus  15  can also include one or more bolting mechanisms  18  that bolt a sheet  13  positioned by the positioning frame  16  to the mine roof 
     In operation, a number of sheets  13  (or a pod  14 ) are stacked on the support frame  12 . As shown in  FIGS. 2   a - b,  a lifting system  24  then picks one or more sheets  13  from the support frame  12  and a feeding system  26  feeds the lifted sheet(s)  13  forward in a longitudinal position. Operators then rotate the sheet(s)  13  (e.g., approximately 90 degrees) and position(s) the sheet  13  on the positioning frame  16  (e.g., length-wise across the upper portio of the “T-shape” in a transverse position). The positioning frame  16  then raises the sheet(s)  13  to the roof and the bolting mechanisms  18  bolt the sheet(s)  13  to the mine roof. 
     As illustrated in  FIG. 1 , the machine  10  also includes mining mechanisms  20 , such as a cutterhead  22 . Although the support frame  12 , the installation apparatus  15 , the lifting and feeding systems  24  and  26 , and the mining mechanisms  20  are illustrated as part of the same machine  10  in  FIG. 1 , such that bolting and mining can be performed in parallel, it should be understood that the mining mechanisms  20  can be included in a separate piece of machinery. For example, in some embodiments, the support frame  12 , installation apparatus  15 , and the lifting and feeding systems  24  and  26  can be included as a piece of machinery for installing roof support sheets  13 , and the mining mechanisms  20  can be included in a separate piece of machinery for mining. 
       FIGS. 2   c  and  2   d  are cross-sectional views of the lifting system  24  and the feeding system  26 , respectively, according to one embodiment of the invention. As shown in  FIG. 2   c , the lifting system  24  includes a sheet starter  30 . The sheet starter  30  is used to pick up a sheet  13  from the support frame  12 . As shown in  FIG. 2   c , in some embodiments, the machine  10  can also include one or more sheet stack leveling pads  31  that keep the support frame  12  and the sheets  13  level while the sheet starter  30  lifts sheets  13  from the support frame  12 . 
       FIGS. 3 and 4   a  illustrate the lifting system  24  in more detail. As shown in  FIG. 3 , the lifting system  24  includes the sheet starter  30 , which includes a first arm  32  having a first end  33   a  and second end  33   b  and a second arm  34  having a first end  35   a  and a second end  35   b.  The end  33   a  of the arm  32  includes a bracket  36  that mounts the sheet starter  30  to the machine  10 . As shown in  FIG. 3 , the arm  32  can include one or more hydraulic systems  38  (e.g., hydraulic cylinders) that allow the arm  32  to be moved. In particular, a first hydraulic system  38   a  can be used to pivot the arm  32  away from and toward a top of the machine  10  (e.g., vertically above where the sheets  13  are positioned), and a second hydraulic system  38   b  can be used to move the arm  32  along the length of the machine  10  (e.g., laterally along the length of the sheets  13 ), such as by extending the length of the arm  32 . For example,  FIG. 4   b  illustrates the lifting system  24  with the arm  32  in a fully raised and extended position. Also, in some embodiments, the hydraulic systems  38   a,    38   b  (or a separate system) also moves the arm  32  horizontally. 
     The end  33   b  of the arm  32  is coupled to the end  35   a  of the arm  34 . As shown in  FIG. 3 , in some embodiments, the arm  34  is positioned approximately perpendicular to the arm  32 . Various mechanical couplings  40  can be used to couple the arm  32  to the arm  34 , and, in some embodiments, the couplings  40  can allow the arm  34  to move relative to the arm  32 . For example, the arm  34  can be coupled to the arm  32  such that it can be pivoted relative to the arm  32 . 
     A pick-up shoe  50  is coupled to the end  35   b  of the arm  34 .  FIG. 5  illustrates the shoe  50  according to one embodiment of the invention in more detail. As shown in  FIG. 5 , the shoe  50  includes a tooth or hook  52  that engages with a sheet  13 . For example, as shown in  FIG. 5 , the sheet of  13  can be constructed from perpendicular grids of wires  54 , and the size and shape of the tooth  52  can be configured to engage with a wire  54  or a joint between two or more wires  54  when the shoe  50  is moved across the surface of the sheet  13 . With the tooth  52  engaged with the wire  54 , the arms  32  and  34  can move the shoe  50  to pick up the sheet  13 . Therefore, in one embodiment, the tooth  52  engages with the sheet  13  without requiring hydraulics to operate and position the tooth  52  (i.e., separate from the arms  32  and  34 ), which makes the lifting system  24  more reliable, efficient, and cost-effective. 
     As described above, the hydraulic systems  38  can be used to position the shoe  50  over the top sheet  13  (e.g., horizontally and vertically) in the support frame  12  or pod  14  and move the shoe  50  to engage the tooth  52  with the top sheet  13 . When the tooth  52  is engaged with the wire  54  of the sheet  13 , the hydraulic systems  38  can then be used to lift the sheet  13  and feed the sheet  13  to the feeding system  26 . In addition, when the lifting system  24  is not being used, the hydraulic systems  38  can be used to position the lifting system  24  to minimize the clearance height of the machine  10  and make the machine  10  more compact. 
     Optionally, in some embodiments, the support frame  12  can also be moved to position a sheet  13  under the shoe  50 . For example,  FIGS. 6   a  through  6   e  illustrate a shoe  50  lifting a sheet  13  according to one embodiment of the invention. As shown in  FIG. 6   a , the shoe  50  can be positioned over the support frame  12 , which contains a pod  14  including a stack of sheets  13 , at a fixed height relative to the support frame  12 . The bottom end of the stack of sheets  13  can then be pushed upward (e.g., using a hydraulic system) relative to the pod  14  and the support frame  12  until the top sheet  13  in the stack engages with the tooth  52  on the shoe  50  (see  FIG. 6   b ). Therefore, because the entire stack of sheets  13  is lifted, the pick-up shoe  50  has little or no need for vertical travel, which reduces the complexity of the hydraulic systems  38 . For example,  FIG. 6   c  illustrates the top sheet  13  of the stack engaged with the tooth  52  of the shoe  50 . With the tooth  52  engaged with the top sheet  13  of the stack, the shoe  50  can be moved forward (e.g., horizontally) to remove the top sheet  13  from the stack and move the top sheet  13  toward the feeding system  26  (see  FIG. 6   d ). In some embodiments, as shown in  FIG. 6   e , the support frame  12  includes an end stop  60  that prevents sheets other than the top sheet engaged with the tooth  52  from being moved when the shoe  50  moves. As also shown in  FIG. 6   e , when the top sheet has been removed from the stack, the stack can be lowered and made ready for the next cycle or can maintain its raised position. 
     Alternatively, the lifting system  24  can include a gripper arrangement to pick up a sheet  13  from the support frame  12  and move the sheet  13  toward the feeding system  26 . For example,  FIGS. 7   a  through  7   e  illustrate a gripper arrangement  70  according to one embodiment of the invention. As shown in  FIG. 7   a , the gripper arrangement  70  includes a shoe  72  that includes pivoting jaws  74 . The pivoting jaws  74  can be opened and closed (e.g., using an actuator) around a wire  54  or a joint between two or more wires  54  of a sheet  13 . Therefore, as shown in  FIGS. 7   a -b, with the shoe  72  positioned (e.g., horizontally) over the top sheet  13  contained in the support frame  12 , the shoe  72  can be lowered (e.g., vertically) such that the jaws  74  are positioned around a wire  54  of the sheet  13 . The jaws  74  can then be closed to engage the wire  54 , as shown in  FIGS. 7   c  and  7   d . Once the jaws  74  are engaged with the wire  54 , the shoe  72  can be raised and moved forward (e.g., horizontally) to remove the top sheet  13  from the support frame  12  and move the sheet  13  toward the feeding system  26 . In some embodiments, the hydraulic systems  38  described above for the shoe  50  can be used to move and position the shoe  72 . However, because the jaws  74  are raised to clear the top sheet  13  before they are lowered around a wire  54 , the hydraulic systems  38  may need to move the shoe  72  higher than shoe  50  with the tooth  52 . Therefore, different hydraulic systems  38  or different control software, hardware, or mechanisms may be needed when the lifting system  24  includes the gripper arrangement  70 . In some embodiments, the gripper arrangement  70  can also be used with a support frame  12  that can be moved as described above with respect to  FIGS. 6   a  through  6   e.    
     It should be understood that other configurations and constructions can be used to remove a sheet  13  from the support frame  12  and move the sheet  13  toward the feeding system  26 . In particular, various combinations of moving the arms  32  and  34 , the stack of sheets  13 , and the support frame  12  can be used to remove a sheet  13 . For example, in some embodiments, the support frame  12  (or the pod  14 ) can be moved to position a sheet  13  horizontally and/or vertically with respect to the lifting system  24 . Also, various shapes and configurations of the shoes  50  and  72 , the tooth  52 , and the jaws  74  can be used to engage with a particular configuration of a sheet  13 . 
     As described above, after the lifting system  24  engages a sheet  13 , the lifting system  24  feeds the sheet  13  toward the installation apparatus  15  (e.g., the positioning frame  16 ). Also, in some embodiments, before reaching the installation apparatus  15 , the feeding system  26  is used to convey the sheets  13  lifted by the lifting system  24 . The feeding system  26  can include a drive assembly  75  and a support  76 . As described below in more detail, the drive assembly  75  engages a sheet  13  (e.g., lifted by the lifting system  24 ) and moves the sheet  13  toward the installation apparatus  15  (e.g., the positioning frame  16 ). The support  76  can include a table, frame, or platform that supports the sheet  13  as the sheet is moved by the drive assembly  75  (e.g., before, during, and/or after the sheet  13  is conveyed by the drive assembly  75 ). Also, in some embodiments, the support  76  can be raised and lowered to disengage the sheet  13  from the drive assembly  75  after the drive assembly  75  has moved the sheet  13  and position the sheet  13  for installation. 
       FIGS. 8 and 9   a  illustrate the feeding system  26  according to one embodiment of the invention. As shown in  FIG. 8 , the support  76  includes a table  80  and the drive assembly  75  includes a sprocket assembly  82 . The sprocket assembly  82  includes one or more sprockets  84  that each includes teeth  85 . In operation, the lifting system  24  lifts a sheet  13  and moves the sheet  13  forward to a point where the sheet  13  (e.g., a wire  54  or a joint between two or more wires  54 ) engages on one or more teeth  85  of the sprocket(s)  84 . The sprocket(s)  84  are driven by a drive system  86 . When the sprocket(s)  84  rotate, the sheet  13  is fed forward by the engaged teeth  85  until the sheet  13  reaches a specified position on the table  80  where the operators can rotate the sheet  13  and position the sheet  13  on the positioning frame  16 . The teeth  85  can have various pitches depending on the pitch of the sheets  13 . Also, different sprocket arrangements may be used. For example, a single sprocket arrangement, as shown in  FIGS. 8 and 9   a - d,  may be used when the sheet  13  is adequately guided by the lifting system  24  and other components. As shown in  FIGS. 10   a -e, the single sprocket arrangement can include a sprocket  84  with nine teeth  85  that engage a sheet  13  with a pitch of approximately  100 . As shown in  FIGS. 9   a - d,  a sheet  13  is presented to the sprocket  84  by the lifting system  26  as the sprocket  84  is rotated clockwise. During this process, the teeth  85  engage with wires  54  of the sheet  13  and the rotating teeth  85  push the sheet  13  forward toward the table  80 . In some embodiments, the sprocket  84  can be mounted on an arm that is movable (e.g., hydraulically raised and lowered) to help lift the sheet  13  clear of the stack on the support frame  12  and take the weight off of the sheet  13 . 
     It should be understood that although a sprocket  84  with nine teeth  85  is illustrated in  FIGS. 8-10 , smaller sprockets and different shaped sprockets may be used. If smaller sprockets are used, however, the component of vertical force on the sprocket teeth may increase. This increased force can be compensated by using two or more staggered sprockets. Also, improved alignment may be achieved by using two or more sprockets  84  on different shafts or a common shaft, as shown in  FIGS. 11 and 12 . For example, the sprockets  84  illustrated in  FIG. 11  have five teeth  85  and a pitch of approximately  50 , which can be used to engage a sheet  13  with a pitch of approximately  150 . Similarly, the sprockets  84  illustrated in  FIG. 12  have seven teeth  85  and a pitch of approximately 75, which can be used to engage a sheet  13  with a pitch of approximately 150. In some embodiments, the sprockets  84  illustrated in  FIGS. 11 and 12  are spaced approximately 300 millimeters apart. Using two or more sprockets can also be used to ensure that there is always at least one tooth engaged with the sheet  13  to keep the sheet  13  progressing. 
     As noted above, the sprocket(s)  84  included in the sprocket assembly  82  can be driven or rotated by a drive system  86 . As also noted above, a hydraulic actuator can be installed that raises and lowers the sprocket(s)  84  (or the entire assembly  82 ) to engage a sheet  13  with or disengage a sheet  13  from the sprocket(s)  84 . For example, an actuator can raise the sprocket(s)  84  when the lifting system  24  feeds a sheet  13  to the feeding system  26  and can lower the sprocket(s)  84  to disengage the sprocket(s)  84  from the sheet  13  when the sheet  13  reaches the table  80  so that operators can position the sheet  13  for installation.  FIG. 9   b  illustrates the sprocket(s)  84  lowered to a “down” position, and  FIG. 9   c  illustrates the sprocket(s)  84  raised to an “up” position. 
     As described above, the table  80  supports a sheet  13  feed by the sprocket assembly  82  so that operators can move the sheet  13  into position for installation (e.g., rotated and placed on the positioning frame  16 ). As shown in  FIGS. 9   b -d, the table  80  can also include a drive or lift system  88 . The lift system  88  can be used to raise or lower the table  80  to a “down” or “up” position or any appropriate level for operators to manually handle and position a sheet  13  (e.g., rotate and place on the positioning frame  16 ). In addition, the lift system  88  can be used to lower the table  80  as needed for clearance around the machine  10  (e.g., roof clearance) when the machine  10  is moving. 
     The ability to move the sprocket(s)  84  and the table  80  allows the feeding system  26  to be positioned in various positions. For example, as shown in  FIG. 9   b , when the table  80  and the sprocket(s)  84  are in a “down” position, the size of the feeding system  26  is minimized. Therefore, the position illustrated in  FIG. 9   b  may be used when the feeding system  26  is not being used or when the size of the machine  10  needs to be minimized to allow the machine  10  to move in tight spaces. When the sprocket(s)  84  are in an “up” position and the table  80  is a “down” position, the feeding system  26  can be in a sheet-feeding position, as illustrated in  FIG. 9   c . In a sheet-feeding position, the sprocket(s)  84  can grab a sheet  13  lifted by the lifting system  24  and feed the sheet  13  to the table  80 . Similarly, when the sprocket(s)  84  are in a “down” position and the table  80  is in an “up” position, the feeding system  26  can be in a sheet rotation position, as illustrated in  FIG. 9   d . In the sheet-rotation position, the sheet  13  is supported by the table  80  and is disengaged from the sprocket(s)  84 , which allows an operator to rotate the sheet  13  and position the sheet  13  on the positioning frame  16 . 
     It should be understood that other configurations and constructions of the drive assembly  75  and the support  76  can be used to grab a sheet  13  from the lifting system  24  and convey the sheet  13  forward where operators can manipulate the sheet  13 . For example, as illustrated in  FIGS. 13   a  and  13   b , the drive assembly  75  can include a chain drive  90 . The chain drive  90  can include one or more sprockets  91   a  that support a conveyor chain  91   b  with rollers  91   c  running on a support track  91   d.  As shown in  FIG. 13   a , the sprocket(s)  91   a  can include eight teeth, which can be used for a conveyor chain  9  lb with a pitch of approximately 75 millimeters. Attached to the conveyor chain  9  lb are one or more teeth  92  that engage with wires  54  on a sheet  13  and push the sheet  13  forward toward the support  76 , which includes a support frame  94 . The support frame  94  can be hydraulically raised and lower to free the sheet  13  from the teeth  92 . 
     Similarly, as illustrated in  FIGS. 14   a  and  14   b , the drive assembly  75  can include a walking frame  100 . The walking frame  100  can include an arm assembly  102  with one or more rotatable teeth  104 . The arm assembly  102  can be driven by a hydraulic system  106  (e.g., a hydraulic cylinder) and can be positioned under the sheet  13 . The teeth  104  can then be rotated upward to engage with wires  54  in the sheet  13 . Once the teeth  104  are engaged, the arm assembly  102  can be driven forward, which also drives the sheet  13  forward. As shown in FIG.  14   b,  the teeth  104  can then be rotated downward to be disengaged from the sheet  13 . With the teeth  104  disengaged, the arm assembly  102  can be moved in a return stroke opposite the direction of travel of the sheet  13  that positions the arm assembly  102  back at a starting position. At the starting position, the arm assembly  102  can then be re-engaged with the sheet  13  (or a new sheet  13 ) to move the sheet  13  through another forward motion. As illustrated in  FIGS. 14   a  and  14   b , the support  76  can include a support frame  108  that receives and supports sheets  13  fed forward by the walking frame  100 , and, in some embodiments, the support from  108  can be hydraulically raised and lowered to free the sheet  13  from the teeth  104 . As shown in  FIG. 14   a , in some embodiments, two walking frames  100  can be used, side-by-side. In this configuration, the walking frames  100  can work in alternate stroke directions, which provides continuous motion to the sheet  13 . 
     In addition, as illustrated in  FIGS. 15   a  and  15   b , the drive assembly  75  can include an edge drive  110 . As shown in  FIG. 15   b , the edge drive  110  can include a plurality of rotating toothed wheels  114  that are driven by one or more drive systems  116  (e.g., a hydraulic motor). As shown in  FIG. 5   b , the wheels  114  include teeth  115  that engage with a side edge of a sheet  13 . In some embodiments, the wheels  114  can be moved (e.g., pivoted) into and out of engagement with the edge of the sheet  13  (e.g., when a new sheet  13  is fed to the edge drive  110  or when a sheet is exiting the edge drive  110 ). As the wheels  114  are rotated, the sheet  13  is driven forward by the teeth  115  engaging with the side edge of the sheet  13 . As illustrated in  FIGS. 15   a  and  15   b , the support  76  can include a support frame  118  that is positioned between the wheels  114  to support the sheet  13  as it is fed forward. In some embodiments, a wheel  114  can be positioned at each corner of the sheet  13 . Therefore, a total of four wheels  114  can be used to convey a sheet  13  to a position where it can be manually handled and positioned by operators. 
     Furthermore, as illustrated in  FIGS. 16   a  and  16   b , the drive assembly  75  can include an oscillating beam  120 . As shown in  FIG. 16   b , the oscillating beam  120  can include a plurality of teeth  122  (e.g., three teeth). Each end of the oscillating beam  120  can be coupled to a driving system (e.g., a hydraulic motor). The driving systems can rotate in sequence such that the oscillating beam  120  is rotated along a circular path under a sheet  13 . Therefore, as the oscillating beam  120  is rotated forward, the teeth  122  are moved upward and into engagement with the sheet  13 . Thereafter, when the oscillating beam  120  is driven forward through its rotation, the sheet  13  is also driven forward by the engaged teeth  122 . When the oscillating beam  120  reaches the end of its forward rotation, the beam  120  is rotated down and away from the sheet  13 , which disengages the teeth  122  from the sheet  13 . After disengaging from the sheet  13 , the oscillating beam  120  is driven backward (i.e., in a direction opposite the direction of travel of the sheet  13 ). After reaching the end of its backward rotation, the oscillating beam  120  is once again rotated upward where the teeth  122  re-engage with a new portion of a sheet  13  (or a new sheet  13 ) and subsequently advance the sheet  13  forward as the oscillating beam  120  is again rotated forward. As shown in  FIG. 16   b , the support  76  can include a support frame  126  that is positioned after the oscillating beam  120  to support the sheet  13  as it is feed forward. In some embodiments, the support frame  126  can be hydraulically raised and lowered to free a sheet  13  from the oscillating beam  120  and allow the sheet  13  to be manually moved by operators. 
     It should be understood that, in some embodiments, the lifting system  24  and/or the feeding system  26  can also rotate a sheet  13  so that the sheet  13  can be positioned on the positioning frame  16 . Therefore, rather than requiring that one or more operator rotate the sheet after being handled by the lifting system  24  and the feeding system  26 , the sheet  13  can be rotated by the lifting system  24 , the feeding system  26 , or a combination thereof. Furthermore, in general, the lifting system  24  and/or the feeding system  26  can be configured to rotate a sheet to any desired position based on the location and configuration of operators, the installation apparatus  15 , the mine roof, or the machine  10 . 
     Accordingly, embodiments of the invention provide robust and efficient methods and systems for lifting and conveying roof support sheets to be installed in a mine. Various features and advantages of the invention are set forth in the following claims.