Some industries, such as machining, machine maintenance, engineering, construction, and many others, use similar types of tools for various purposes, and over the years, the terms describing such tools have become interchangeable. This is the case with shackles and clevises, as both are very similar in their design.

Over the past few decades, if you were to name something a clevis, someone would correct you by explaining that the device in question is actually a shackle and vice versa. In this article, we’ll discuss the similarities and the difference between shackles and clevises.

The Similarities Between Shackle and Clevis Fasteners

Both shackles and clevises are U-shaped mechanical coupling devices that are usually closed by some type of fastener, whether a bolt or a threaded pin. In most cases, these U-shaped pieces are used to facilitate attaching a chain, a rope, or a wire rope for rigging purposes, hoisting, or towing applications.

Both shackles and clevises are designed in varying levels of working load limit (WLL), with various types of pins, and in various styles, and contrary to popular belief, their size is specified by the diameter of the shackle or clevis body, and not by the diameter of the threaded bolt, or a clevis fastener.

However, their main difference is mostly in their working load limit and certain nuances in their design, which also dictate their overall application. You’ll find those differences below.

The Difference Between the Shackle and a Clevis Fastener

The main difference is in the working load limit and their applications; clevises are mostly used in farming towing applications, with shackles typically used in construction, lifting, and rigging.

Clevises are most typically constructed to allow a reasonable amount of vertical movement and an appreciable amount of horizontal or lateral movement, mostly associated with towing applications in farming and sailboat rigging.

Additionally, these types of fasteners are typically closed with a non-threaded clevis pin for easier uncoupling of farming equipment in towing applications. However, it’s worth noting that they might be used in conjunction with a cotter pin that would prevent the clevis pin’s accidental removal due to vibrations.

On the other hand, shackles are mostly used in rigging and lifting, as they’re made of stronger materials, such as alloy or stainless steel. Additionally, they’re usually secured via a threaded pin or a threaded bolt, which makes them suitable for overhead lifting. There are two different types of shackles:

• Anchor Shackles — Also known as bow shackles, these have a generously-sized O-shaped loop that’s better suited for multipoint connection.
• Chain Shackles — More commonly known as D-shackle, these are shaped like a chain link and are thus narrower than typical anchor shackles. Their design reduces the rigging line movement, as they’re designed to primarily take the load in-line.

Different Pin Types

While clevises are primarily fastened via a non-threaded clevis pin and shackles via a threaded bolt, pin types are interchangeable in most cases. Here are three different types of pins:

• Screw Type — These pins allow rapid securing of the shackle or a threaded clevis by applying torque.
• Pin Types — These are straightforward to install and remove for the shackle or a clevis, which limits their use due to them being susceptible to disengagement.
• Nut, Bolt, and Cotter Pin Type — This is the most secure type of fastening a shackle or a clevis since the nut secures the bolt, and the cotter pin prevents the nut from unfastening due to excessive vibration. These excel at withstanding radial and torsional loads, but their complex installing and removal process makes them more suitable for semi-permanent applications.

Summary

All shackles are clevises, but not all clevises are shackles. Clevises represent a broader spectrum of load-bearing elements, which includes shackles — elements specifically designed for rigging and lifting.

If you want to learn more about shackles and clevises, please visit Reid Supply, a hardware and components supplier from North America. Reid Supply also offers downloadable literature, allowing customers to find any parts and components specifications that might interest them.