Lifting shackles are an essential tool for securing and lifting heavy loads. Their prevalence and simple construction have led to widespread, incorrect use. Many people use the wrong type of shackle for specific applications, which leads to the unsafe operation of heavy machinery and large, unsecured loads. This, in turn, can result in injury. You should understand the different types of shackles and their applications, along with their proper storage, handling, and requirements. This complete guide to lifting shackles will teach you how to choose the correct shackles and handle them properly.
What Are Lifting Shackles?
People have used shackles in the lifting industry for decades. Their main purpose is to lift, secure, and rig heavy loads, objects, and equipment. Lifting shackles are the final link in a connection chain or sling setup, where they form a durable connection between the load-lifting device and the payload.
The Different Types of Lifting Shackles
Shackles come in a wide array of shapes, sizes, and types. They consist of two main parts: the body and the pin. The body is usually horseshoe-shaped or U-shaped, with the pin affixed through both ends of the loop. The pins are normally threaded, or part threaded. They can also act as a clevis fastener, with a cross-hole included for a split pin or tang to hold them in place. While variation exists, most shackles are designed and manufactured in one of two main configurations: chain/D-shackles and bow/anchor shackles. Let’s take a look at both.
Chain/D-Shackles
Chain shackles, also called D-shackles, have a narrow, D-shaped body that closely resembles the shape of a standard chain loop or link. They're considered the “traditional” form of shackles, and people use them in a wide range of common, everyday scenarios. Chain shackles are a suitable choice for moderate to heavy loads that are being lifted in line. You should avoid using chain shackles for non-vertical lifting since they can bend or twist under enough force. You can find chain shackles made of stainless steel, galvanized steel, alloy steel, and more. Shackles made from alloy steel have a higher working load than other materials.
Bow/Anchor Shackles
Bow shackles, or anchor shackles, are widely flared, with an O-shaped variant of the D-shackle format. Their rounded shape allows them to support heavier payloads at various points around their circumference, meaning they can handle multiple loads from different directions. They can also accommodate wider lifting straps. However, when compared to chain/D-shackles, bow shackles have a lower overall weight tolerance.
Certification and Safety Standards
As previously mentioned, shackles made from alloy steel have a higher working load than shackles made from higher tensile steel. Mild steel shackles are still manufactured for the general engineering industry, but standards for these shackles no longer exist for lifting purposes. Other types of shackles meet US Federal Specifications.
Complying with safety standards is essential. When you're purchasing shackles, it's important to specify the size, type, and standard number you require, and check to ensure the supplied product is in full compliance with those standards. If you have doubts about the shackles, you can ask the supplier or manufacturer to provide documents and certificates that prove they comply with proper safety standards. Shackles certified for lifting purposes are normally stamped with the WLL, manufacturer’s mark, and batch ID number. If your shackles don't have these markings, you should double-check their compliance and make sure they're certified for general lifting purposes.
Things To Keep in Mind
When you're picking out shackles, you'll need to keep in mind the safe working load (SFL), the shape, and the pin type. The working load limit needs to be equal to, or higher than the total load you plan to impose on the shackle. If the load placed on the pin is evenly distributed over its length, the load-bearing capacity of the pin increases. Remember: distributing the load across the pin doesn't increase the strength of the shackle's body. The right body shape depends on the intended use of your shackles. You should use a shackle with a jaw opening that is consistent with an adequate articulation of the connection.
Storing and Handling Your Lifting Shackles
After removing your shackles from the lifting setup, you should immediately reassemble it. If you leave the pins loose, they could damage the threads. More importantly, the pin and body of each shackle are very unique. If the pin is left out of multiple shackles, reassembling the body and pin at a later date becomes difficult, if not impossible. This scenario could lead to the replacement of not just one, but an entire batch of shackles.
How To Use Lifting Shackles Safely
Operating large, unwieldy equipment and heavy loads comes with inevitable safety risks. With the right precautions, it's possible to reduce these risks and guarantee optimal safety for everyone involved in the lifting process.
When you're handling lifting shackles, you should always:
- Store and handle shackles correctly
- Inspect shackles before use and before placing them into storage
- Select the correct pattern of shackle and pin
- Fully tighten the pin
- Ensure the load acts through the centerline of the shackle, using spacers when necessary
To guarantee your own safety and the safety of others at the work site, it's important to never:
- Use shackles with bent pins or deformed bodies
- Force, hammer, or wedge shackles into position
- Load shackles eccentrically
- Replace the pin with a bolt
- Put pins in contact with moving parts that can loosen or unscrew them
- Shock load shackles
Now that you've read through the complete guide to lifting shackles, you should have a clearer idea about what lifting shackles are, and about the safest, most effective ways to use them.
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