Abstract:
A portable apparatus for pulling a cable through a conduit includes a frame that has a base and caster wheels. The apparatus further includes a boom that has at least one roller configured to guide a rope connected to the cable along the boom. The boom also includes a main boom pivotally connected to the base and an upper boom pivotally connected to the main boom. A drive unit connects to the boom and includes a rotatable spool configured to pull the rope along the boom. The apparatus further includes a lift pivotally connected to the frame and the boom. The lift is operable to move the boom relative to the frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/825,499 filed Jun. 29, 2010, which will issue as U.S. Pat. No. 8,434,741 on May 7, 2013, and which claims the benefit of U.S. Provisional Patent Application No. 61/221,290 filed Jun. 29, 2009, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to powered cable pullers for routing cables and wiring through conduits. 
         [0004]    Cable pullers are well-known devices for pulling power cables, data cables, or other wiring through both horizontal and vertical building conduits; the cables are usually pulled upwardly (referred to as an “up-pull”) or downwardly (referred to as a “down-pull”). Typical cable puller designs include a rope that connects to and pulls cables through the conduit and a conduit adapter that connects to the conduit to help support the device. In some designs, the conduit adapter is reconfigurable or interchangeable with other adapters to connect to conduits of various sizes. Typical puller designs also include a boom connected to the conduit adapter that guides the rope to a drive unit that rotates to pull the rope. The boom includes multiple sections that are connected by one or more pivotal joints. The pivotal joints permit the boom to be accurately repositioned such that the device is suitable for use with conduits that terminate at various heights. 
         [0005]    Typical cable puller designs, while eliminating the need for contractors or other technicians to manually pull cables through building conduits, include several drawbacks. For example, some pullers are designed to have relatively high pulling capacities (e.g., 6000 lbs or more) to overcome large friction forces when a cable is pulled through a long conduit. High pulling capacity is typically provided by using a larger drive unit. In addition, the boom and other components are typically thick metal components to provide durability and resistance to deflection due to the high pulling forces. As a result, the large drive unit and boom cause the device to be very heavy (e.g., 75 lbs. or more) and difficult to reposition. A technician can be fatigued easily by lifting and carrying such a puller if many consecutive pulls are performed. 
         [0006]    A number of designs have been created in an attempt to overcome the drawback of having to carry a cable puller between different locations. For instance, some cable puller designs include a base with wheels that support the drive unit and the boom. Such designs permit even larger drive units and booms to be used to further increase pulling capacity. The size of the base may prevent these pullers from accessing smaller areas in which the aforementioned designs fit easily. In addition, puller designs with wheels are typically difficult for a technician to push because the base is only inches off the ground. 
         [0007]    All of the aforementioned puller designs are difficult to accurately reposition after the puller is moved to the general location of the conduit (i.e., difficult to accurately adjust the boom to connect the conduit adapter to the conduit). This problem occurs in part due to the weight of the cable puller as described above. In addition, the pivotal joints of the boom each include a pin that must be completely removed to reposition the boom sections. After the boom is accurately repositioned, the pin must be inserted into the joint while holding the puller in engagement with the conduit. This can be particularly difficult if a single technician must set up the power puller without assistance. 
         [0008]    Further still, some of the aforementioned designs require a technician to partially disassemble the boom to switch between appropriate up-pull and down-pull configurations. For example, it may be necessary to separate the boom sections and reverse the orientation of several boom sections relative other sections. Such actions can be time consuming and can fatigue a technician. 
         [0009]    Considering the limitations of the previous powered puller designs, a need exists for a design that is easily moved and reconfigured at a work site. A need also exists for such a cable puller to have a high pulling capacity. 
       SUMMARY OF THE INVENTION 
       [0010]    In one aspect, the present invention provides a portable apparatus for pulling a cable through a conduit. The apparatus comprises a frame and a boom pivotally connected to the frame that includes at least one roller configured to guide a rope connected to the cable along the boom. Ground engaging wheels support the frame, at least some of the wheels being caster wheels that are rotatable about a vertical axis relative to the frame to steer the apparatus. 
         [0011]    In another aspect, the present invention provides an apparatus for pulling a cable through a conduit. The apparatus comprises a frame and a boom pivotally connected to the frame. The boom includes at least one roller configured to guide a rope connected to the cable along the boom. The boom further includes a first member, a second member, and a joint connecting the first member to the second member. The joint defines a first axis about which the second member is pivotable relative to the first member and a second axis about which the second member is rotatable relative to the first member. The second axis is perpendicular to the first axis. 
         [0012]    In another aspect, the invention includes a lift pivotally connected to the frame and the boom. The lift is operable to move the boom relative to the frame. 
         [0013]    The foregoing and other advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
           [0015]      FIG. 1  is a perspective view of a powered cable puller of the invention performing an up-pull; 
           [0016]      FIG. 2  is a side view of the powered cable puller of  FIG. 1  performing an up-pull; 
           [0017]      FIG. 3  is a partial side view of a boom of the powered cable puller of  FIG. 1 ; 
           [0018]      FIG. 4  is a partial top view of the boom and a boom joint of the powered cable puller of  FIG. 1 ; 
           [0019]      FIG. 5A  is a side view of a pin of the boom joint in a fixed position; 
           [0020]      FIG. 5B  is a side view of the pin of  FIG. 5A  with a handle pulled to move the pin to a rotation position; 
           [0021]      FIG. 5C  is a side view of the pin of  FIG. 5A  with the handle pulled and rotated to lock the pin in the rotation position; 
           [0022]      FIG. 6  is a sectional view of the boom joint along line  6 - 6  of  FIG. 4 ; 
           [0023]      FIG. 7  is another partial side view of a boom of the powered cable puller of  FIG. 1 ; 
           [0024]      FIG. 8  is a partial side view of a frame of the powered cable puller of  FIG. 1 ; 
           [0025]      FIG. 9  is a side view of the powered cable puller of  FIG. 1  performing a down-pull; 
           [0026]      FIG. 10  is a perspective view of the powered cable puller of  FIG. 1  performing a down-pull; 
           [0027]      FIG. 11  is a perspective view of the powered cable puller of  FIG. 1  performing a side-pull; 
           [0028]      FIG. 12  is a perspective view of the powered cable puller of  FIG. 1  in a storage position; 
           [0029]      FIG. 13  is a side view of the powered cable puller of  FIG. 1  in the storage position; 
           [0030]      FIG. 14  is a side view of the powered cable puller of  FIG. 1  as viewed from the opposite direction as  FIG. 13 ; 
           [0031]      FIG. 14A  is a detail view of the boom along line  14 A- 14 A of  FIG. 14 ; 
           [0032]      FIG. 14B  is a detail view along line  14 B- 14 B of  FIG. 14 ; 
           [0033]      FIG. 15  is a rear view of the powered cable puller of  FIG. 1  in the storage position; 
           [0034]      FIG. 16  is a bottom view of the powered cable puller of  FIG. 1  in the storage position; and 
           [0035]      FIG. 17  is a schematic illustration of a pump and an actuator of the powered cable puller of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    The particulars shown herein are by way of example and only for purposes of illustrative discussion of the embodiments of the invention. The particulars shown herein are presented to provide what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention. The description taken with the drawings should make apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. 
         [0037]    Referring now to the figures and particularly  FIG. 1 , a powered cable puller  10  of the present invention includes a conduit adapter  12  for engaging a conduit  14  that may be part of an electrical box or recessed in a wall or surface  16  of a building. The puller  10  further includes a boom  18  that supports the conduit adapter  12  and a drive unit  20  that rotates to pull a rope  22  connected to one or more cables (e.g., power cables, data cables, or other wiring). The boom  18  is pivotally supported by a frame  24  and is reconfigurable to perform various types of pulls, such as up-pulls ( FIGS. 1 and 2 ), down-pulls ( FIGS. 9 and 10 ) and side-pulls ( FIG. 11 ), and to fold to a storage position ( FIGS. 12-16 ). These components and their interactions are described in further detail in the following paragraphs, beginning with the conduit adapter  12  and then proceeding to the boom  18  and the frame  24 . 
         [0038]    Referring to  FIGS. 2 ,  3 , and  10 , the conduit adapter  12  includes a semi-circular adapter end  26  that engages the conduit  14 . The adapter end  26  defines a passageway  28  to permit the rope  22  to pass therethrough. The adapter end  26  also connects to a support bracket  30  that connects to the boom  18 . The support bracket  30  preferably releasably connects to the boom  18 , for example, through threaded fasteners and the like, to permit interchangeability with adapters of other sizes. 
         [0039]    The boom  18  includes a first end that has an adapter joint  32  that engages the conduit adapter  12 . The adapter joint  32  includes a first roller  34  that is rotatably disposed between adapter side plates  36 . The first roller  34  guides the rope  22  from the conduit adapter  12  and along the boom  18  to the drive unit  20 . The adapter side plates  36  each include a plurality of holes  38  that accommodates a first removable cotter pin assembly  40 . The first pin  40  also extends through holes in distal brackets  42  that are pivotally connected to the side plates  36 . As such, the first pin  40  locks the side plates  36  relative to the distal brackets  42  when the pin  40  extends through one set of the holes  38 . The first pin  40  may be removed from the holes  38  and permit the adapter joint  32  to pivot and be repositioned. It may be useful to pivot and reposition the conduit adapter  12 , for example, if the surface  16  has a slight incline. In addition to supporting the first pin  40 , the distal brackets  42  also permit pivotal movement of the first roller  34  and the adapter side plates  36  about an adapter axis  43 . 
         [0040]    Still referring to  FIGS. 2 ,  3 , and  10 , the adapter joint  32  connects to an upper boom  44 . The upper boom  44  preferably includes a telescoping boom  46  that fixedly connects to the distal brackets  42 . The telescoping boom  46  also moves within a sleeve boom  48  such that the length of the upper boom  44  may be varied. The telescoping boom  46  and the sleeve boom  48  may be fixable to one another by a second removable cotter pin assembly  50 . In addition, the booms  46  and  48  may each be formed from tube stock material (e.g., 2″×3″ tubular steel) and include separate arms  52  and  54  connected by one or more cross members  56 . The end of the upper boom  44  opposite the distal brackets  42  includes proximal brackets  58  that define a boom pivot axis  60 . The upper boom  44  may pivot relative to other sections of the boom  18  about the boom pivot axis  60 . It may be useful to pivot and reposition the upper boom  44 , for example, to adjust the boom  18  to an appropriate height for a cable pull or to fold the boom  18  to the storage position. 
         [0041]    Referring now to  FIGS. 3-6 , the upper boom  44  connects to a main boom  62 . The main boom  62  includes a boom joint  64  that connects to the proximal brackets  58  at the boom pivot axis  60 . The boom joint  64  includes a second roller  66  rotatably disposed between joint side plates  68 . The second roller  66  guides the rope  22  to the drive unit  20 . The joint side plates  68  each include an arcuate adjustment slot  70 . In a preferred embodiment, each arcuate adjustment slot  70  includes a plurality of slot indentations  72 , such as semi-circular surfaces. Each slot indentation  72  is positioned across from a slot indentation  72  on the opposite side of the slot  70 . As such, each pair of opposite slot indentations  72  defines a slot enlargement  73 , such as a circular hole that has a diameter larger than the width of arcuate connecting holes  75  between the slot enlargements  73 . The slot enlargements  73  and the connecting holes  75  accommodate a second pin  74  as described below. 
         [0042]    The second pin  74  (shown separately from the cable puller  10  in  FIGS. 5A-5C ) includes a shaft  71  defining an axis  77 . The shaft  71  is axially movable between a fixed position and a rotation position in which the upper boom  44  is fixed and pivotable, respectively, relative to the main boom  62 . In the fixed position, locking sections  76  of the shaft  71  are each disposed within one of the slot enlargements  73  in the joint side plates  68  (note that in  FIG. 4  the locking sections  76  are enlarged and shown protruding from the joint side plates  68  for clarity). The locking sections  76  have a diameter larger than the width of the arcuate connecting holes  75 . As such, the locking sections  76  are constrained in the slot enlargements  73  and prevent the upper boom  44  from pivoting relative to the main boom  62 . As shown in  FIG. 5B , the shaft  71  of the second pin  74  is moved from the fixed position to the rotation position by pulling a handle  80  fixedly connected to the shaft  71 . This action results in rotation sections  78  of the shaft  71  being moved into the adjustment slot  70 . The rotation sections  78  have a diameter smaller than the width of the arcuate connecting holes  75 . As a result, in the rotation position the shaft  71  is permitted to move through the adjustment slot  70  and the upper boom  44  is permitted to pivot relative to the main boom  62 . 
         [0043]    In a preferred embodiment, the second pin  74  also includes a spring  84  that biases the shaft  71  towards the fixed position. The handle  80  also includes an annular spacer  81  having fingers  83  accommodated, in the fixed position, in finger grooves  85  of a bracket  87  connected to one of the proximal brackets  58  by fasteners (not shown) or the like. As shown in  FIG. 5B , the fingers  83  move from the finger grooves  85  when the handle  80  is pulled and the shaft  71  moves to the rotation position. As shown in  FIG. 5C , the handle  80  may then be turned, for example, by a quarter turn, to move the fingers  83  out of alignment with the finger grooves  85 . The handle  80  may then be released to permit the fingers  83  to abut the outer surface  91  of the bracket  87  and thereby hold the shaft  71  in the rotation position. 
         [0044]    During use, a technician may pull and turn the handle  80  to secure the shaft  71  of the second pin  74  in the rotation position as described above. The technician may then configure the upper boom  44  to place the adapter  12  generally in the area of the conduit  14 . Then, the technician may turn the handle  80  (for example, by an opposite quarter turn to align the fingers  83  and the finger grooves  85 ) such that the spring  84  forces the shaft  71  towards the fixed position. However, the upper boom  44  may still be rotated relative to the main boom  62  unless the locking sections  76  of the pin  74  are aligned with a set of slot enlargements  73 . That is, the sides of the locking sections  76  will abut the side of the joint side plates  68  surrounding the arcuate connecting holes  75  unless the locking sections  76  of the pin  74  are aligned with a set of slot enlargements  73 . The spring  84  will force the second pin  74  into a set of slot enlargements  73  once the locking sections  76  of the pin  74  are aligned with a set of slot enlargements  73 , after which the upper boom  44  is fixed relative to the main boom  62 . 
         [0045]    From the above, it should be apparent that the second pin  74  does not need to be completely removed from the boom joint  64  to reposition the upper boom  44 . In addition, the second pin  74  does not need to be awkwardly reinserted into the boom joint  64  as the upper boom  44  is held in the proper position. As such, the boom joint  64  permits the upper boom  44  to be locked and unlocked relative to the main boom  62  by a technician only using a single hand. 
         [0046]    Referring now to  FIGS. 4 and 6 , the joint side plates  68  fixedly connect to a joint bracket  86  that supports a revolute joint  88 . The revolute joint  88  includes a joint sleeve  93  that rotatably supports a joint shaft  95  fixedly connected to the joint bracket  86 . The joint shaft  95 , and therefore the upper boom  44 , is rotatable about a revolute axis  90  that is perpendicular to the boom pivot axis  60 . Rotation about the revolute axis  90  permits the upper boom  44  to be easily rotated to perform a down-pull ( FIGS. 9 and 10 ) or a side-pull ( FIG. 11 ). Of course, the rope  22  should be routed along the boom  18  after the upper boom  44  is rotated to the desired position so that the rope  22  does not contact or become tangled with the boom  18 . 
         [0047]    Referring specifically to  FIG. 6 , the joint sleeve  93  includes upper and lower pin openings  97  that are alignable with a first pin passageway  99  of the joint shaft  95  when performing an up-pull ( FIGS. 1 and 2 ) or a down-pull ( FIGS. 9 and 10 ). A pin assembly  89 , such as a fastener that is threadably engagable with the openings  97  or the passageway  99 , may be inserted into one of the openings  97  and the passageway  99  to lock the revolute joint  88  in a position for an up-pull or a down-pull. In some embodiments, as shown in  FIG. 6 , the pin assembly  89  may include a perpendicularly extending grip  103  for ease of rotating the pin assembly  89 . The pin assembly  89  may also be removed to rotate the upper boom  44  and align the openings  97  with a second pin passageway  101  of the joint shaft  95  extending perpendicularly through the first pin passageway  99 . Thereafter, the pin assembly  89  may be inserted into one of the openings  97  and the second passageway  101  to lock the revolute joint  88  in a position to perform a side pull ( FIG. 11 ). 
         [0048]    The revolute joint  88  advantageously permits the puller  10  to perform the different types of pulls described above. In addition, the revolute joint  88  also permits the puller  10  to operate in small spaces; for example, the puller  10  may perform a side-pull in a narrow corridor that is only slightly wider than the frame  24 . Further still, the revolute joint  88  permits the puller  10  to switch between different types of pulls without requiring disassembly of the boom; for example, the upper boom  44  does not need to be separated from the main boom  62 . 
         [0049]    In addition to providing the multiple pivot axis structure described above, the boom joint  64  also supports handles  61  that extend along the pivot axis  60 . When the boom  18  is folded to the storage position ( FIG. 12 ), the handles  61  are positioned such that they may be easily grasped by a technician and the puller  10  may be moved thereby. 
         [0050]    Referring now to  FIGS. 2 ,  7 , and  10 , the revolute joint  88  connects to an intermediate bracket  92  that is supported by an intermediate boom  96 . The intermediate boom  96  may include separate tube stock arms  98  and  100  connected by one or more cross members  102 . The intermediate boom  96  pivotally connects to a lower boom  104  that may include separate tube stock arms  106  and  108 . The intermediate and lower booms  96  and  104  may be fixable to one another by a second removable cotter pin assembly  110 . The lower boom  104  includes stopper plates  111  that support the intermediate boom  96  in the operating position and support brackets  112  that support the intermediate boom  96  in the storage position. The lower boom  104  removably supports the drive unit  20 , which may be any appropriate design known to those skilled in the art, such as capstan that has a rotatable spool. In addition, a proximal end of the lower boom  104  pivotally connects to the frame  24 . 
         [0051]    Referring to  FIGS. 8 ,  10 , and  11 , the frame  24  includes a base  114  that has a generally rectangular shape. The base  114  is defined by several arms  116  that may be, for example, the same tube stock material used to form the arms of the boom  18 . The rear end of the base  114  connects to rear wheels  124 . The rear wheels  124  may be braked casters that rotate about a vertical axis to permit, together with the handles  61 , the puller  10  to be easily steered by a technician. These components also permit the puller  10  to be easily steered even if it is heavy and has a relatively high pulling capacity. 
         [0052]    One of the base arms  116  preferably removably supports several conduit adapters  12  of various sizes that may be interchanged with the conduit adapter  12  connected to the boom  18 . The opposite base arm  116  supports a pump  126 , such as a manually-driven hydraulic pump including a manual pump handle  127 , that is in fluid communication with an actuator  128  that pivotally connects to the base  114  and the boom  18  to raise and lower the boom  18 . 
         [0053]    Referring specifically to  FIG. 17 , a hydraulic fluid reservoir  151  supplies hydraulic fluid through a hydraulic fluid delivery line  153  to the pump  126  as the handle  127  is pivoted toward the pump  126 . The pump  126  supplies hydraulic fluid through an actuator line  155  to the actuator  128  to extend the actuator rod  141  and thereby lift the boom  18 . In addition, the pump  126  includes a manual valve  157 , such as a screw valve commonly used with bottle jacks and the like, positioned along a hydraulic fluid return line  159  connected to the reservoir  151 . The valve  157  may be opened to permit the boom  18  to lower under its own weight and thereby force hydraulic fluid to pass through the return line  159  and into the reservoir  151 . The return line  159  preferably includes a flow limiter  161  to reduce the flow rate as the hydraulic fluid returns to the reservoir  151 , thereby forcing the boom  18  to lower slowly. That is, the flow limiter  161  has a fluid passageway having a smaller cross-sectional area than that of the actuator line  155 , so as to slow down the rate that the boom  18  will lower under its own weight when the valve  157  is opened. The pump  126  may also include other appropriate components recognized by those skilled in the art, such as check valves, pilot valves, and the like. 
         [0054]    The actuator  128  also pivotally connects to a linkage assembly  130  that raises and lowers the lower boom  104  as the actuator  128  extends and retracts, respectively. As best understood from  FIG. 11 , the actuator  128  extends to unfold the linkage assembly  130  and raise the lower boom  104 . Conversely, the actuator  128  retracts to fold the linkage assembly  130  and lower the lower boom  104 . 
         [0055]    Referring to  FIGS. 8 and 11 , the linkage assembly  130  is supported by a cross member  131  connected between the base arms  116 . The linkage assembly  130  includes lower links  133  that are preferably identical components. Each lower link  133  includes a first end  135  pivotally connected to the cross member  131  and a second end  137  pivotally connected to an actuator cross member  139 . As the name implies, the actuator cross member  139  connects to the extendable rod  141  of the actuator  128 . Upper links  143  of the linkage assembly  130  are also preferably identical components and each includes a first end  145  pivotally connected to the actuator cross member  139 . Each upper link  143  also includes a second end  147  ( FIG. 8 ) pivotally connected to the one of the arms  106  or  108  of the lower boom  104 . 
         [0056]    The actuator  128  preferably only extends a limited amount (e.g., an amount such that the lower boom  104  rotates at most 30 degrees relative to the base  114 ). The pump  126 , actuator  128 , and the linkage assembly  130  advantageously support the boom  18  during a pull and during setup for a pull, thereby reducing the amount of lifting required by a technician. These components also help hold the conduit adapter  12  in engagement with the conduit  14  during a down-pull. Alternatively, the pump  126  and the actuator  128  could be replaced by a manual crank lift (not shown). 
         [0057]    A front end of the base  114  connects to one or more boom supports  132  that support the lower boom  104  in the storage position. The front end of the base  114  also connects to front wheels  134  that are preferably fixed axle wheels. Each of the base arms  116  preferably connects to a lifting handle  136 . The lifting handles  136  may be used to lift the puller  10 , for example, into a vehicle. The sides of the base  114  also preferably connect to a drive unit bracket  138  that supports the drive unit  20  in the storage position. 
         [0058]    The powered puller  10  is preferably set up for a pull as follows: starting from the storage position, the rear wheels  124  are locked using the brakes. Next, the hydraulic pump  126  is operated, for example, using the manual pump handle  127 , to pivot and lift the lower boom  104  above the frame  24 . The intermediate boom  96  is then unfolded from the lower boom  104  so that the stopper plates  111  support the intermediate boom  96 . The intermediate boom  96  is also locked in place by the pin assembly  110 . Next, the second pin  74  is moved to the second position to permit the upper boom  44  to pivot upwardly. The second pin  74  is then moved to the first position to fix the upper boom  44  relative to the intermediate boom  96 . Next, the telescoping boom  46  may be extended from the sleeve boom  48  and the upper boom  44  may be rotated about the revolute axis  90  if a down-pull or a side-pull is to be performed. Finally, the first pin  40  may be removed such that the conduit adapter  12  may be repositioned to engage the conduit  14 . 
         [0059]    From the above disclosure, it should be apparent that the powered cable puller of the invention may provide any combination of the following advantages: high pulling capacity and ease of movement and reconfiguration in an operating position, performance of various types of pulls even in relatively small spaces, and ease of transport in a storage position. 
         [0060]    A preferred embodiment of the invention has been described in considerable detail. Many modifications and variations to the preferred embodiment described will be apparent to a person of ordinary skill in the art. Therefore, the invention should not be limited to the embodiment described, but should be defined by the claims that follow.