Abstract:
A portable anchor for supporting a line along a side of a structure, having a beam member comprising a line support end and a counterweight end distal to the line support end, a counterweight attachable to the beam member at a counterweight location proximate the counterweight end, a support member that supports the beam member at a pivot location arranged between the line support end and the counterweight end, a line stand-off rotatably mounted to the support member and rotatable from a line deployed position and a storage position where the line stand-off guides the line away from the side of the structure in the deployed position; and an adjustable locking device that allows rotation of the support member, and selectably fixes the support member to the beam member at a selected angle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the 2 Feb. 2008 filing date of U.S. Provisional Application 61/025,364 which is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to the field of roof anchors for securing a line along a side of a structure. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 6,539,676, issued to the present inventor and incorporated by reference herein, describes a portable roof anchor that is small enough and light enough to be carried by one person. Such roof anchors are useful for accessing the sides of a building from a roof top via a rope that is secured to the anchor. Small portable roof anchors are generally useful for supporting only one man or a limited amount of equipment weight. It is desired to increase the versatility of a portable roof anchor without significantly decreasing its load carrying capability or portability or increasing its weight or portability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The invention is explained in the following description in view of the drawings that show: 
           [0005]      FIG. 1  is a side view of a first embodiment of a portable roof anchor. 
           [0006]      FIG. 2  is a side view of a second embodiment of a portable roof anchor. 
           [0007]      FIG. 3  is a side view of the standoff arm of the portable roof anchors of  FIGS. 1 and 2 . 
           [0008]      FIG. 4  is a top view of the standoff arm of  FIG. 3 . 
           [0009]      FIG. 5  is a side view of the adjustable locking apparatus of the portable roof anchors of  FIGS. 1 and 2   
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]      FIG. 1  illustrates one embodiment of a portable roof anchor  10  installed on the top of a building  14  having a generally flat roof  12  and a small parapet wall  13 . The portable roof anchor  10  may be used for supporting a line  16  along a vertical side  18  of the building  14 , such as for cleaning the exterior of the windows of the building or for performing other maintenance activities along the vertical side  18  of the structure. The line may be a cable, rope, wire or other load carrying material as may be used for suspending a machine or person along the side  18  of the building  14 . 
         [0011]    Roof anchor  10  includes a beam member  20 . Beam member  20  is illustrated as a linear-shaped structure having a line support end  22 , a counterweight end  24 , and a pivot location  26 . Beam member  20  may have any desired cross-sectional shape for carrying bending moment loads, such as an I-beam, tube, bar or channel, for example. Beam member  20  may be formed of any metal, alloy or composite material and is preferably formed of a material having a high strength-to-weight ratio in order to improve the portability of the device. The cross-section of the beam member  20  may be different at different points along the length of the beam member  20 . For example, to increase the lifting capability of the device for rescue applications, it may be necessary to form at least a portion of the beam member near the pivot location, where the bending moments will be the highest, from a solid bar of material, while a portion of the beam member having a lower level of stress may be formed from an open channel material. 
         [0012]    A line support member  28  is attached to beam member  20  at a line support location  30  proximate the line support end  22 . Line support member  28  may be a turnbuckle, hook, or a groove or notch formed in the beam member  20 . Alternatively, line  16  may simply be tied or wrapped around beam member  20  at line support location  30  depending upon the safety requirements of a particular application. Line support location  30  is located a distance D 1  from pivot location  26  along the length of beam member  20 . A counterweight  32  is attached to the beam member  20  at a counterweight location  34  located a distance D 2  from pivot location  26 . Beam member  20  may be upwardly supported at pivot location  26  so that the downward force exerted on the line support member  28  is counterbalanced by the downward force exerted by the counterweight  32 . The mechanical advantage provided by the ratio of D 2 /D 1  reduces the mass of the counterweight  32  that must be used in order to counterbalance a given line load. The ratio of D 2 /D 1  is selected so that when the beam member  20  is vertically supported at the pivot location  26 , the moment of inertia about the pivot location  26  created by the counterweight  32  will exceed the moment of inertia about the pivot location  26  created by a line  16  connected to the line support member  28  by a predetermined safety margin; for example, a 4:1 safety margin. 
         [0013]    Beam member  20  may be formed to be expandable along its length dimension so that it may be carried to the roof  12  of a building  14  in one configuration having a first shorter length, then reconfigured while on the roof  12  to a second configuration having a greater length. In this manner, beam member  20  may be more conveniently carried through stairways, elevators or other roof access openings without being disassembled. In the embodiment of  FIG. 1 , beam member  20  includes a hollow outer member  36  and an inner member  38  slidably extending partially into the hollow outer member  36 . A plurality of holes  40  are formed at various locations on the inner member  38  so that a removable connector, such a bolt  42  and mating nut (not shown) may be used to lock the two portions of the beam member  20  together to have a selected length D 2 . The ratio of D 2 /D 1  may thus be varied, for example from 20:1 to 40:1. In this manner, portable anchor  10  may be used in a variety of locations, some of which do not provide sufficient space for the extension of beam member  20  to its full length. Furthermore, beam member  20  may be delivered to the roof  12  in a first configuration having its shortest length to simplify the delivery process, and then reconfigured to a desired second length. To compensate for any reduction in length D 2  necessary to accommodate a job-specific physical interference, a corresponding increase in the weight of counterweight  32  or a reduction in the line load may be provided. 
         [0014]    The vertical support of beam member  20  may be provided by a support member such as bipod  44  having a ladder-style support foot  46  pivotally connected to each leg. Bipod  44  is connected to beam member  20  at pivot location  26 . It is desired that vertical support member  44  should be restrained from rotating with respect to beam member  20  about pivot location  26  in order to prevent the roof anchor  10  from collapsing, thereby presenting an unsafe situation. Prior art designs such as those described in U.S. Pat. No. 6,539,676 simply affix the two members  20 ,  44  at pivot location  26  by means of a bolted connection. The portable roof anchor  10  of the present invention accomplishes this joint with an adjustable locking apparatus  45 , as will be described more fully below, in order to allow the beam  20  to be affixed to the bipod  44  at pivot point  26  at any of a plurality of selectable angles there between. The adjustable locking apparatus  45  allows for rotation of the bipod  44  relative to the beam member  20  about a horizontal axis through pivot location  26 . A pivot location  27  is also provided for horizontal rotation of the beam member  20  relative to the bipod  44  about a vertical axis. Rotation about the horizontal axis at pivot location  26  allows the bipod  44  to be maintained at a desired back slant angle greater than 0°, for example 5-10°, relative to the surface it is placed on even when the height of bipod  44  is adjusted or when the bipod  44  is placed on a surface that is higher or lower than the roof surface  12  upon which the counterweight  32  is resting. Such back slant serves to increase the stability of the devise by insuring the weight of the load bears nearly straight down on the bipod  44 , thereby virtually eliminating any forward pull forces on the apparatus. The adjustable locking apparatus  45  is joined to the beam member  20  with a rotatable joint such as a pin at pivot location  26 . A notch  47  formed in the adjustable locking apparatus  45  (as shown more clearly in  FIG. 5 ) is engaged over and rests on the head of the bipod  44  to prevent rotation of the adjustable locking apparatus  45  relative to the bipod  44 . The beam member  20  can then be rotated relative to the bipod  44  and adjustable locking apparatus  45  about pivot location  26  to a desired rotational angle, and it is then secured at the selected position by inserting a bolt through one of the positioning holes  49  that becomes aligned with a hole (not shown) formed through the beam member  20 . A plurality of discrete positioning holes may be provided to allow for a range of predetermined angles with maximum strength of the joint, or a curved slot may be used for infinite positioning flexibility with less strength in the joint.  FIG. 5  shows locking apparatus  45  with a combination of discrete holes  49  and slot  70  for purposes of illustration, however, in various embodiments the locking apparatus  45  may have only discrete holes  49  or only slot  70  or both. Optionally, a rotatable joint  27  allows rotation about an axis  71  perpendicular to a longitudinal axis of the beam member  20  so that the counterweight  32  and counterweight end of the beam member  20  may be moved along the roof surface  12  without moving the bipod  44 , such as may be useful to avoid an obstruction on the roof for a particular application. Once in the desired position, a bolt/nut combination is tightened to secure the rotatable joint  27 . 
         [0015]    A handle  48  may be attached to beam member  20  for carrying of the device. Handle  48  may also function as a location for connecting a safety line  50  to the roof anchor  10 . The handle  48  is preferably located a short distance toward the counterweight end  24  from a line-deployed center of gravity location  52 . In one embodiment, this distance may be approximately 12-18 inches. In this manner, a single person may easily lift and move the roof anchor  10  with the attached counterweight  32  and deployed line  16  by placing one hand on the handle  48 , and by cradling the beam member  20  with the other hand positioned at a location between the center of gravity  52  and the line support end  22 . By using such a strategically located handle, the operator is able to easily lift, tilt and turn the roof anchor assembly  10  in its deployed configuration with the line  16  over the side  18  of the building  12  in order to move from place to place while avoiding any obstacle on the roof. For example, lightning rods are commonly mounted to a parapet on a corner of a building. With prior art roof rigs, it was necessary to retrieve the entire line in order to move from one side of a lightning rod to another, since such rigs were too heavy or bulky to be lifted. In one embodiment, the portable roof anchor of  FIG. 1  with 300 feet of 7/16 inch nylon mountain-climbing rope and counterweights attached may weigh only about ninety pounds. One person lifting the device  10  with one hand on handle  48  and one hand cradling under the beam member  20  can easily tilt the line supporting end  22  upward to clear a lightning rod with the line  16  fully deployed. Similarly, an operator can step over or around obstacles on the roof  12  which would be difficult to maneuver around with a prior art wheeled device. 
         [0016]    A line storage member such as brackets  54  may also be attached to beam member  20 . Line  16  may be wrapped around the brackets  54  for transport, and may be securely tied or otherwise affixed to brackets  54  when in use for supporting a load along a side  18  of building  14 . Other styles of line storage members may be used, such as a single unit having two opposed raised members for wrapping the line  16 . Furthermore, when line  16  is wrapped around the line storage member, the line itself may serve as a handle or shoulder pad  56  for carrying the device. By spacing brackets  54  apart and on either side of a center of gravity  58  of the device in its line-stored configuration with the counterweight  32  removed, the line handle  56  may be held with one hand or two, or it may be slung over the shoulder of the person carrying the device to and from a roof  12 . 
         [0017]    In another embodiment as shown in  FIG. 2 , the line storage member may be a roller mechanism  59  that allows the line  16  to be rolled off of the roller mechanism  59  to lower the supported load downward along the side of the structure  14  and drawn back onto the roller mechanism  59  to draw the supported load upwardly. In such an embodiment, the line is not affixed to a line support member  28  as shown in  FIG. 1 , but rather is looped over a pulley  61  disposed at the line support end of the beam member, as shown in  FIG. 2 . Pulley  61  may be attached to beam member  20  via an adjustable support in order to provide proper alignment of the roller mechanism  59  and pulley  61  whenever an angle is created around the vertical axis at pivot location  27 . 
         [0018]    Counterweight  32  may be a single weight member or a plurality of individual weight members. Counterweight  32  is connected to beam member  20  at or very close to the counterweight end  24  in order to maximize dimension D 2 . Unlike prior art devices, roof anchor  10  advantageously uses the counterweight  32  as a foot for resting on the roof  12 , thereby eliminating the cost and weight associated with a separate foot/wheel structure at the counterweight end  24 . Counterweight  32  may preferably have a bottom portion cross-sectional area that is greater than a top portion cross-sectional area, such as the generally triangular shape as seen from perspective of the side elevation view of  FIG. 1 . Other such shapes include a half-moon shape and an inverted T-shape as viewed from a side perspective. By rotatably connecting the counterweight  32  to the beam member  20  within its top portion, the counterweight  32  becomes self-leveling with the relatively larger flat bottom surface being horizontal no matter what angle the beam member  20  has to the horizon. Because the counterweight  32  rests directly on the roof  12 , this advantageously provides a large, flat bottom surface to reduce the weight per unit area exerted on the roof  12 . This structure also provides a relatively taller counterweight  32 , which may be advantageous if it becomes desirable to have a winch  60  or other device mounted on the bottom of beam member  20 . This type of counterweight shape also provides a very stable base for resting the portable anchor  10  on the roof  12 . 
         [0019]    In one embodiment, beam member  20  includes a 2½ inch square, high strength aluminum alloy tube with a wall thickness of 0.125 inch as the outer member  36  and a mating inner member having a wall thickness of 0.1875 inch. A standard 2 inch turnbuckle (eyebolt)  28  is attached to the inner tube approximately 3 inches (D 1 ) from the pivot location  26 . The overall length of the beam member  20  may be adjusted by sliding the inner member  38  into the outer member  36  to obtain a D 2  dimension ranging from about 5 feet or about 6 feet to about 10 feet (in various embodiments) in 6 inch increments, thus providing a ratio of D 2 :D 1  of about 20:1 to 40:1. A plurality of counterweights  32  may be connected to the beam member  20  to provide a desired load supporting capability. The counterweights may be steel plate, each weighing about 11 pounds. The bipod  44  may be formed to include a top pair of opposed angle brackets which together define a channel into which the inner tube  38  may be placed and affixed. The bipod  44  may support the beam member  20  about 17½ inches above the rooftop  12 . The total weight of such an assembly, including 46 pounds of counterweight and 300 feet of 7/16 inch diameter nylon line would be about 92 pounds, light enough to be conveniently handled by one person. The counterweights may be removed from the beam and carried separately, then reassembled on the rooftop  12  at a working location. The length of the beam assembly  20  may then be adjusted to a maximum length permitted by any obstructions present at the working location. 
         [0020]    Not all building roofs are flat. The roof anchor  10  can also be used on a peaked roof by positioning the bipod feet  46  on one side of the roof, at or very near to the peak of the roof. The line  16  would then be routed along the opposite side of the roof and over the side of the building. The line load would then be transferred to the beam member  20  and resisted by the bipod support  44  in much the same manner as described above, but with the axis of the loads being rotated from horizontal/vertical by the angle of the roof. The portable roof anchor  10  may also be used on a roof having a parapet by placing the bipod feet  46  on the top of the parapet, or by providing a bipod  44  having sufficient height to clear the beam member  20  over the parapet. Alternatively, the device may be used without a bipod  44  by laying the beam member directly onto the parapet at the pivot location  26 , or with different bipod heights, or with a bipod capable of extending to different heights to accommodate varying parapet wall heights. Advantageously, as the inclination angle of the beam member  20  is changed in different applications, the angle of the bipod  44  can be maintained at a desired 5-10° back slant relative to the surface that it is resting on by operation of adjustable locking apparatus  45  as described above. 
         [0021]    Referring back to  FIG. 1 , the portable anchor  10  may also be provided with a standoff arm  11 . Standoff arm  11  is illustrated in more detail in the side view of  FIG. 3  and the top view of  FIG. 4 . The standoff arm  11  is rotatably attached to the bipod  44  at pivot location  15  so that it may be moved from an uppermost position storage position (not shown) where it is drawn into the bipod  44  for ease of portability to a deployed lowermost position (as illustrated in  FIGS. 1 and 2 ) where it engages line  16  at line support bar  19  and urges the line away from the bipod  44  and away from the vertical side  18  of building  14 . The line support bar  19  may be affixed at any of several positions along the length of the standoff arm  11  to provide a selectable degree of line standoff. The standoff arm  11  is held at its lowermost position and prevented from further rotation by the engagement of the top surface of its rearwardly extending portion  17  with a horizontal cross brace member of bipod  44 . Advantageously, the standoff arm  11  defines an angle with the plane of the uppermost section of the bipod  44  of greater than 90° plus the back slant angle of the bipod  44  when in its lowermost position So that the weight of the line  16  against the line support bar  19  urges the standoff arm  11  downward without the need for a locking mechanism. When the bipod  44  is positioned at an angle of 5-10° back slant relative to the roof surface, the angle between the standoff arm  11  and the upper section of the bipod  44  may be more than 90°+10° or more than 100°, or in one embodiment at least 105° or about 107° to provide a small downward angle relative to horizontal. In this manner, the weight of line  16  will keep the rearwardly extending portion  17  of standoff arm  11  urged against the cross brace of bipod  44  during use, but will allow the standoff arm  11  to be folded upward against the bipod  44  easily when not in use. 
         [0022]    While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein.