Flexible sling with delineation markings

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.

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.

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.”

In an exemplary embodiment, sling10is a flexible web sling with a generally flat, elongate body12when laid out across a surface. Sling10can be formed from a polymer material such as nylon or polyester, but other high tensile strength fabrics suitable for hoisting loads are contemplated herein. Sling10can further be formed as a single ply or multi ply sling. Sling10has a length L which as shown, is measured from one looped end14to the opposing looped end14. Sling10also has a width W (represented by a dashed line to distinguish from delineation markings) perpendicular to length L and is measured across body12. 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 ends14can be configured as “eye & eye” ends formed from the same material as body12with a flat or twisted (with respect to body12) orientation. Looped ends14can alternatively be metallic (e.g., a triangle choker configuration) or otherwise formed from a different material than body12. Looped ends act as attachment points for securing sling10to a clamp, hoist, link, or the like. The load capacity of sling10can be affected by any of the flexible material, number of plies, length, width, eye configuration, and other factors not presented herein. Sling10can have a load capacity ranging from 800 lbs (362.9 kg) to over 50 tons (45, 359 kg) depending on such factors.

FIG. 2is a detailed view of body12showing visual delineation markings M with looped ends14omitted for simplicity. As discussed herein, markings M is a collective reference to markings M0-M7as are discussed below, but can generally refer to any number of markings M0-Mndepending on the embodiment. In the embodiment shown, markings M are discrete lines on body12oriented in the widthwise direction of sling10. Center marking M0marks the center point of body12. Typically, the center point of sling10will 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 ends14), are pairs of markings M1-M7. As discussed herein, a pair of markings is considered to be two markings on opposing sides of and equidistance from center marking M0. That is, a pair of markings is symmetrically disposed about centerline M0. Markings M1represent a first pair of markings moving outward from M0. In the embodiment shown, there are seven pairs of markings, each marking in a respective pair being equidistant from M0relative to the corresponding, oppositely disposed marking.

Zones Z1-Z7are also shown, and can, along with zones Z1-Znin an alternative embodiment, be collectively referred to as zones Z. Zones Z1-Z7represent the space between adjacent markings along body12. For example, first zone Z1represent the region of body12between markings M0and M1, second zone Z2represents the region of body between markings M1and M2, and so on. As such, zones Z1-Z7are distributed relative to center marking M0in a mirror-image fashion like pairs of markings M1-M7.

Each zone has a correspondingly numbered length L1-L7(only labeled on one side of M0) which also represents the distance between adjacent markings. In the embodiment shown, L1>L2, L2<L3, and L3=L4=L5=L6=L7. More specifically, L1can be 20 in (0.51 m) such that the distance between opposing markings M1is 40 in (1.02 m). L2can be 4 in (0.101 m) such that the distance between opposing markings M2is 48 in (1.22 m). One common cargo pallet size is L 48 in×W 40 in, so markings M1/zone Z1can be used (i.e., visually referenced by a rigger) to center a pallet if such a pallet is placed onto sling10in the widthwise direction, while markings M2/zone Z2can be used if such a pallet is placed onto sling10in the lengthwise direction, as is discussed in greater detail below. Each of L3-L7can 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 strap10. 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 L1-Lncan be equal, or each can differ from the previous/subsequent length. In one alternative embodiment, each of L1-L7can 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 M1and M2may be black, as their relatively different distribution from center marking M0as compared to markings M3-M7is somewhat visually distinct. Each pair of markings M3-M7can have a color different from markings M1and M2and also from the adjacent marking. One possible pattern could be a repeating sequence of blue-red-green such that the overall color pattern is M1(black), M2(black), M3(blue), M4(red), M5(green), M6(blue), M7(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 body12which 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 inFIG. 4) of sling10is visible inFIGS. 1 and 2, however, rotating sling10by 180° would reveal an identically delineated bottom side B (labeled inFIG. 4) such that either side can face upward (toward the pallet/load) and allow for visual load centering.

FIG. 3is a partial view of body112showing only the first few markings M/zones Z. Body112is substantially similar to body12discussed above, except that body112includes hatching between neighboring markings to facilitate visual identification of the zones. As shown inFIG. 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 body12. Other lined or unlined patterns (e.g., stippling, fully colored zones, etc.) are contemplated herein.

In either of body12or body112, markings M and zone patterns can be added to strap12in various ways. In an exemplary embodiment, markings M and any zone patterns can be an ink or dye applied to sling10using 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 sling10. It is further possible to use both methods, or other suitable methods not listed herein.

FIG. 4is a simplified side view showing load16centered over body12of sling10. Looped ends14are again omitted for simplicity.FIG. 5is a perspective view of load16rigged using two slings10just prior to hoisting.FIGS. 4 and 5will be discussed together. It should be noted that in markings M and zones Z are visible in the side view ofFIG. 4to facilitate visualization of the alignment of load16relative to body12, but would not typically be present on the sides of body12. Rather, markings M and/or zones Z would be present and visible on top side T and bottom side B of body12.

Load16includes sides18and line GCwhich marks the center of gravity of load16. As shown inFIG. 4, the center of gravity is aligned with center marking M0of body12. Such alignment can help prevent issues resulting from an unbalanced load once hoisted into the air. Additionally, sides (edges)18align with markings pair M2which, as discussed above, can indicate a standard pallet oriented lengthwise on body12. In practice, multiple slings10can be used for safely hoisting load16. To prepare load16for hoisting, a rigger can lay out the slings10to be used on a loading surface (e.g., the ground). Load16can be positioned such that its center of gravity, which is some cases is its true center, is aligned with marking M0of each sling10. If desired, the rigger can additionally or alternatively use a pair of markings (e.g., M2) to position load16. Once positioned, slings10can be pulled up along sides18in order to attach looped ends14to a hoisting device. As can be seen inFIG. 5, bottom side B of slings10becomes visible once lifted up along sides18, and the rigger can further visualize that load16is positioned as desired by referencing the identical delineations markings bottom side B. In an alternative embodiment, one sling10can be disposed perpendicular to and cross the other sling10, depending on the load16and/or loading protocols.

Sling10can 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.