A sling is an assembly designed to connect a load to a lifting device, so that the load may be lifted, turned, or moved. The slings shown in this catalog are available in a variety of body styles, number of legs, and types of splices and attachments. A choice of sizes is available to provide a Rated Capacity suitable for the safe handling of specified loads. Slings are designed to be used in several types of hitches so that the best configuration can be selected for controlling the load.
There are four basic sling configurations, which meet most moving, lifting and turning requirements:
- VERTICAL (Straight Pull);
- BASKET HITCH:
- CHOKER HITCH; and,
- (MULTIPLE LEG SLING (Bridle).
Items 1, 2, and 3 are basically single leg slings.
Users of our products are urged to select slings of the proper Rated Capacity to safely perform the work required. Type of hitches, body style, and leg angles affect Rated Capacity. Use only slings designed for the job, keep the load under control at all times, and protect slings from damage. This practice is essential to safe economical service life. Rated Capacities for the various types of slings are given in this catalog.
Figure 1 — Basic Sling Hitches
CERTIFIED SLINGS — Any of our Slings may be certified at the customer’s request for a slight extra cost. A sling specified as “certified” will be individually tested on our specially-designed proof-testing machine to a load of twice the sling’s designed Rated Capacity in straight pull. A certificate is furnished to attest to the fact that a sling has actually sustained a load of twice the Rated Capacity, far outweighs any slight difference in price.
TABLE ONE – SLING CAPACITY
|LARGEST ANGLE ANY
LEG AND HORIZONTAL
The Rated Capacity of a sling, is the maximum load in tons that it is designed to lift when used as prescribed under favorable working conditions. Rated Capacity is based on nominal wire rope breaking strength; splicing or end attachment efficiency; design factor; number of parts of rope in the sling; type of hitch (vertical, choker, or basket); angle of loading; and diameter of curvature around which the sling is bent.
The Rated Capacity for each type and size of sling is given in the specification tables in this catalog, and show ratings for slings used in vertical, choker, and basket hitches. Multiple leg slings show the Rated Capacity when the angle between any leg and the horizontal is 600 45° and 30°.
The Rated Capacity of a sling decreases as the leg angle increases. The Capacity Reduction Factor is the cosine of the largest included angle between any leg and vertical. The Sling Capacity Reduction Factor Table gives reductions for angles of 00 to 90° from the horizontal, in 5° increments. Normailv,„ a sling should not be used when the horizontal angle exceeds 45°. Angles shown above 450 are primarily to illustrate the drastic strength loss that occurs at the higher angles. In special cases where limited head room requires the use of a sling with a horizontal angle greater than 450, great care must be exercised in selecting a sling with a proper Rated Capacity.
NOTE: Normally a sling should not be used when the vertical angle exceeds 45 degrees.
Figure 2 — Sling Leg Tension at Various Angles
The Rated Capacity of any sling decreases as the leg angle from vertical increases. The illustrations above, show how tension increases in each leg of a multiple leg sling (or bridle hitch) at angles of 90, 60, 45, and 30 degrees.
SLING BODY STYLES
There are several basic body styles used in the fabrication of wire rope slings. Each has specific advantages, and selection is a matter of matching characteristics to the application. Body Styles include: (1) General Purpose (made from regular wire rope; (2) Cable-Laid; (3) Braided; and, (4) Flat Belt. Slings can be assembled with any body style, number of legs, and a variety of end .attachments.
1. General Purpose Body
Each sling is a single length of regular wire rope. Rope maybe— Improved Plow Steel (IFS), — Extra Improved Plow Steel (EIPS), or special high-strength types such as EEIPS. Wire rope with either Fiber Core (FC) or Independent Wire Rope Core (IWRC) may be used. An Independent Wire Rope Core is preferred when mechanical splices are used. Unless otherwise specified, We use IWRC rope for all General Purpose Bodies.
The 6×19 Classification IWRC is a rugged general purpose wire rope used for most slings up through 1-1/8″ size. The 6 x 37 Classification IWRC is commonly used in sizes above 1-1/8″ because of better flexibility in larger sizes. Wire rope slings using the General Purpose Body Style are rugged, economical, and easy to inspect. This is the style most often used for average applications.
Figure 3 — Typical Sling Using General Purpose Body.
2. Cable-Laid Body
Each sling leg is an all-steel wire rope that has been machine made (laid-up) from seven smaller wire ropes. A Cable-Laid Body is very flexible, easy to handle, and has excellent resistance to kinking. Recommended for slings where flexibility and ease of handling are the main considerations. Not recommended for use on loads where high abrasion or cutting might be experienced.
Figure 4 — Typical Sling Using Cable-Laid Body.
3. Braided Body
The body of each sling leg is hand-braided from a number of smaller wire ropes. The loops are an integral part of the braided body. Almost any number of ropes may be used to form a single body. An 8-Part Braided Body is the most popular and is round in shape. A 4-Part Braided Body is excellent for some applications, and also has a round cross-section. 6-Part Braided Body has a flat cross-section and is widely used. Braided slings approach the flexibility of a fiber rope and are difficult to dogleg or kink. This flexibility allows braided slings to be used on large, heavy and difficult to handle loads. They are easy to handle, but not recommended where abrasion is a primary destructive factor.
(A) 4-Part Round Braid
(B) 6-Part Flat Braid
(C) 8-Part Round Braid.
Figure 5 Typical Slings Using Braided Bodies.
4. Flat Belt Body
A Flat Belt Body consists of parallel smaller wire ropes sewn together to form a flat belt. Six ropes are generally used. This type of body is for special lifting slings such as are used for coils of steel, or other materials with a center hole, through which the sling is passed, A Basket Hitch is employed, and sling ends terminate in Loops or Slip-Through Thimbles.
Figure 6 — Typical Sling Using Flat Belt Body.