Patent Publication Number: US-2022219946-A1

Title: Flexible sling with delineation markings

Description:
BACKGROUND 
     The present disclosure relates to overhead hoisting applications, and more specifically, to flexible slings for hoisting loads. 
     In the construction trade, flexible slings can be used to hoist and move materials. This requires great care to ensure the safety of the both the materials and the personnel on the ground. One aspect of exercising proper care is to ensure that the load is properly centered prior to hoisting. This reduces the risk of an unbalanced load breaking free from the slings. Construction materials come in many different shapes, sizes, and masses, and accordingly require different classes of sling suitable for the load. Current slings are typically only marked (via a tag, stamp, etc.) to indicate sling length and load capacity. As such, it can be an inexact and time-intensive endeavor to properly center a load prior to hoisting. 
     SUMMARY 
     A flexible sling includes two oppositely disposed attachment points defining a first end and a second end of the sling, and an elongate flexible body extending in a lateral dimension from the first end to the second end, the body having a top side and a bottom side. Each of the top side and the bottom side includes a center line marking a center of the body, a first pair of lines symmetrically disposed about the center line, a second pair of lines symmetrically disposed about the center line between the first end and the second end, and the first pair of lines, and a third pair of lines symmetrically disposed about the center line between the first end and the second end, and the second pair of lines. 
     A method for centering a load on a flexible sling includes laying the sling across a loading surface to expose a top side of the strap, aligning a center of gravity of the load with a first line of the sling visible on the top side, the first line being a center line of the sling, aligning a first end of the load with a second line of the sling visible on the top side, and aligning a second end of the load with a third line of the sling visible on the top side. Each of the second line and the third line are symmetrically disposed about the center line of the sling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a delineated sling. 
         FIG. 2  is a simplified view of the body of the delineated sling according to one embodiment. 
         FIG. 3  is a partial view of the body of the delineated sling according to an alternative embodiment. 
         FIG. 4  is a simplified side view showing a load centered over the delineated sling. 
         FIG. 5  is a perspective view of the load rigged with two delineated slings just prior to hoisting. 
     
    
    
     While the above-identified drawing figures set forth one or more embodiments of the present disclosure, other embodiments are also contemplated. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings. Like reference numerals identify similar structural elements. 
     DETAILED DESCRIPTION 
     This disclosure presents a flexible sling with means for visually centering a load prior to hoisting. The sling includes delineation markings in select increments from a marked center point to facilitate with placing a load (e.g., a pallet or other container) on the slings such that the load will be centered once the sling(s) and load are lifted from the ground. The markings can be configured as discrete lines or as larger zones in one or more colors or hatchings to provide a quick visual reference for the load riggers. As used herein, the term sling can also be used interchangeably with terms such as “strap” and “rigging.” 
       FIG. 1  is a top plan view showing sling  10 . Sling  10  includes body  12  disposed between looped ends  14 . Body  12  includes delineation markings (labeled collectively as M in  FIG. 1 ).  FIG. 2  is a simplified illustration of body  12  showing delineation markings M of  FIG. 1  in greater detail.  FIGS. 1 and 2  will be discussed together. 
     In an exemplary embodiment, sling  10  is a flexible web sling with a generally flat, elongate body  12  when laid out across a surface. Sling  10  can be formed from a polymer material such as nylon or polyester, but other high tensile strength fabrics suitable for hoisting loads are contemplated herein. Sling  10  can further be formed as a single ply or multi ply sling. Sling  10  has a length L which as shown, is measured from one looped end  14  to the opposing looped end  14 . Sling  10  also has a width W (represented by a dashed line to distinguish from delineation markings) perpendicular to length L and is measured across body  12 . Length L can, in an exemplary embodiment, be between 8 ft (2.44 m) and 16 ft (3.66 m) which are common lengths used in the construction trade. However, alternative embodiments can include lengths as low as 4 ft (1.22 m) up to 30 ft (9.14 m) to accommodate additional sizes and types of materials. Width W is generally less than length L and can range from 1 in (0.025 m) to 24 in (0.061 m) based on length L (i.e., to scale up in size) and/or based on the type of web sling (e.g., a standard elongate sling vs. a wide body cargo sling). Looped ends  14  can be configured as “eye &amp; eye” ends formed from the same material as body  12  with a flat or twisted (with respect to body  12 ) orientation. Looped ends  14  can alternatively be metallic (e.g., a triangle choker configuration) or otherwise formed from a different material than body  12 . Looped ends act as attachment points for securing sling  10  to a clamp, hoist, link, or the like. The load capacity of sling  10  can be affected by any of the flexible material, number of plies, length, width, eye configuration, and other factors not presented herein. Sling  10  can have a load capacity ranging from 800 lbs (362.9 kg) to over 50 tons (45, 359 kg) depending on such factors. 
       FIG. 2  is a detailed view of body  12  showing visual delineation markings M with looped ends  14  omitted for simplicity. As discussed herein, markings M is a collective reference to markings M 0 -M 7  as are discussed below, but can generally refer to any number of markings M 0 -M n  depending on the embodiment. In the embodiment shown, markings M are discrete lines on body  12  oriented in the widthwise direction of sling  10 . Center marking M 0  marks the center point of body  12 . Typically, the center point of sling  10  will be based on its length (e.g., at 4 ft if length L is 8 ft). Moving in a laterally outward direction (i.e., toward looped ends  14 ), are pairs of markings M 1 -M 7 . As discussed herein, a pair of markings is considered to be two markings on opposing sides of and equidistance from center marking M 0 . That is, a pair of markings is symmetrically disposed about centerline M 0 . Markings M 1  represent a first pair of markings moving outward from M 0 . In the embodiment shown, there are seven pairs of markings, each marking in a respective pair being equidistant from M 0  relative to the corresponding, oppositely disposed marking. 
     Zones Z 1 -Z 7  are also shown, and can, along with zones Z 1 -Z n  in an alternative embodiment, be collectively referred to as zones Z. Zones Z 1 -Z 7  represent the space between adjacent markings along body  12 . For example, first zone Z 1  represent the region of body  12  between markings M 0  and M 1 , second zone Z 2  represents the region of body between markings M 1  and M 2 , and so on. As such, zones Z 1 -Z 7  are distributed relative to center marking M 0  in a mirror-image fashion like pairs of markings M 1 -M 7 . 
     Each zone has a correspondingly numbered length L 1 -L 7  (only labeled on one side of M 0 ) which also represents the distance between adjacent markings. In the embodiment shown, L 1 &gt;L 2 , L 2 &lt;L 3 , and L 3 =L 4 =L 5 =L 6 =L 7 . More specifically, L 1  can be 20 in (0.51 m) such that the distance between opposing markings M 1  is 40 in (1.02 m). L 2  can be 4 in (0.101 m) such that the distance between opposing markings M 2  is 48 in (1.22 m). One common cargo pallet size is L 48 in×W 40 in, so markings M 1 /zone Z 1  can be used (i.e., visually referenced by a rigger) to center a pallet if such a pallet is placed onto sling  10  in the widthwise direction, while markings M 2 /zone Z 2  can be used if such a pallet is placed onto sling  10  in the lengthwise direction, as is discussed in greater detail below. Each of L 3 -L 7  can be 12 in (0.305 m) to correspond to larger pallet/load sizes. It should be noted that alternative embodiments can include either fewer or more than seven markings and zones, depending on factors such as the length of strap  10 . For example, there may be between three and ten zones and accordingly, three to ten pairs of markings M. Additionally and/or alternatively, the lengths of the zones can vary. For example, lengths L 1 -L n  can be equal, or each can differ from the previous/subsequent length. In one alternative embodiment, each of L 1 -L 7  can be equal to one another and range from 8-12 in (0.203-0.304 m). Other configurations are contemplated herein. 
     To help quickly visually distinguish one pair of markings from another, each marking pair can be color coded. For example, markings M 1  and M 2  may be black, as their relatively different distribution from center marking M 0  as compared to markings M 3 -M 7  is somewhat visually distinct. Each pair of markings M 3 -M 7  can have a color different from markings M 1  and M 2  and also from the adjacent marking. One possible pattern could be a repeating sequence of blue-red-green such that the overall color pattern is M 1  (black), M 2  (black), M 3  (blue), M 4  (red), M 5  (green), M 6  (blue), M 7  (red). Alternatively, only two, or more than three colors can be used in any sequence suitable for visual identification of each pair. Suitable colors should stand out from the color of body  12  which can be a shade of yellow in an exemplary embodiment. In yet another alternative embodiment, each pair of markings can have a different line thickness than an adjacent pair and may or may not be the same color. It is important to note that only the top side T (labeled in  FIG. 4 ) of sling  10  is visible in  FIGS. 1 and 2 , however, rotating sling  10  by 180° would reveal an identically delineated bottom side B (labeled in  FIG. 4 ) such that either side can face upward (toward the pallet/load) and allow for visual load centering. 
       FIG. 3  is a partial view of body  112  showing only the first few markings M/zones Z. Body  112  is substantially similar to body  12  discussed above, except that body  112  includes hatching between neighboring markings to facilitate visual identification of the zones. As shown in  FIG. 3 , each zone includes herringbone-style hatching. Such hatching may be done in a single color or various colors in a pattern as was discussed with respect to body  12 . Other lined or unlined patterns (e.g., stippling, fully colored zones, etc.) are contemplated herein. 
     In either of body  12  or body  112 , markings M and zone patterns can be added to strap  12  in various ways. In an exemplary embodiment, markings M and any zone patterns can be an ink or dye applied to sling  10  using a screen-printing method (e.g., stamping, stenciling, silk screening, etc.). Alternatively, markings M and/or zone patterns can be a fabric that is stitched or woven into the flexible material of sling  10 . It is further possible to use both methods, or other suitable methods not listed herein. 
       FIG. 4  is a simplified side view showing load  16  centered over body  12  of sling  10 . Looped ends  14  are again omitted for simplicity.  FIG. 5  is a perspective view of load  16  rigged using two slings  10  just prior to hoisting.  FIGS. 4 and 5  will be discussed together. It should be noted that in markings M and zones Z are visible in the side view of  FIG. 4  to facilitate visualization of the alignment of load  16  relative to body  12 , but would not typically be present on the sides of body  12 . Rather, markings M and/or zones Z would be present and visible on top side T and bottom side B of body  12 . 
     Load  16  includes sides  18  and line G C  which marks the center of gravity of load  16 . As shown in  FIG. 4 , the center of gravity is aligned with center marking M 0  of body  12 . Such alignment can help prevent issues resulting from an unbalanced load once hoisted into the air. Additionally, sides (edges)  18  align with markings pair M 2  which, as discussed above, can indicate a standard pallet oriented lengthwise on body  12 . In practice, multiple slings  10  can be used for safely hoisting load  16 . To prepare load  16  for hoisting, a rigger can lay out the slings  10  to be used on a loading surface (e.g., the ground). Load  16  can be positioned such that its center of gravity, which is some cases is its true center, is aligned with marking M 0  of each sling  10 . If desired, the rigger can additionally or alternatively use a pair of markings (e.g., M 2 ) to position load  16 . Once positioned, slings  10  can be pulled up along sides  18  in order to attach looped ends  14  to a hoisting device. As can be seen in  FIG. 5 , bottom side B of slings  10  becomes visible once lifted up along sides  18 , and the rigger can further visualize that load  16  is positioned as desired by referencing the identical delineations markings bottom side B. In an alternative embodiment, one sling  10  can be disposed perpendicular to and cross the other sling  10 , depending on the load  16  and/or loading protocols. 
     Sling  10  can alternatively have a variety of configurations not discussed above, such as a braided body and/or looped ends, or an endless (ring-like) configuration. Additionally, markings M/zones Z can be printed onto a sleeve or cover which is fitted over an unmarked flexible sling. The sleeve could be removable attached to the underlying sling using snaps, buttons, or other suitable attachment means. 
     The disclosed sling allows for easy visualization of load placement to help ensure proper balance prior to hoisting. Although discussed with respect to the construction trade, the disclosed sling can generally be used in material-handling environments such as warehouses, shipyards, or other industrial settings. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.