Turnbuckle Types and Load Ratings: Complete Selection Guide

In the rigging and construction world, lifting a load is only half the battle. Often, the harder part is holding it in place, tensioning it, or pulling it into alignment. That is where the humble turnbuckle comes in.

To the untrained eye, a turnbuckle looks like a simple screw mechanism. To a rigger, it is a precision instrument used to tune the tension of a guy wire on a 500-foot tower or adjust the plumb of a structural steel column.

However, turnbuckles are also one of the most frequently misapplied pieces of hardware in the industry. We often see light-duty, hardware-store-grade turnbuckles used in critical rigging applications, a mistake that can lead to catastrophic failure.

At Holloway Houston , we live by the code that every link in the chain matters. This guide will break down turnbuckle types, how to interpret load ratings, and the critical safety factors required by ASME B30.26.

What is a Turnbuckle?

A turnbuckle is a mechanical device used to adjust the tension or length of a rope, cable, tie rod, or other tensioning system.

The mechanics are simple but brilliant: it consists of a body with two internal screw threads. One end is threaded right-hand, and the other is threaded left-hand.

• How it works : When you rotate the body of the turnbuckle, both end fittings are screwed in (or out) simultaneously.
• The Result : You can generate thousands of pounds of tension without twisting the attached cables or wires.

While they are used in everything from boxing rings to garden fences, industrial turnbuckles are engineered lifting and rigging components. They are rated to specific Working Load Limits (WLL) and must be selected based on the specific tensioning application.

Common Applications

• Rigging & Lifting : Adjusting the length of sling legs to level an unbalanced load.
• Structural Steel : "Plumbing up" columns and beams during erection.
• Marine : Tensioning ship rigging and lashing cargo.
• Construction : Guy wires for towers, tents, and suspension bridges.

Types of Turnbuckles by End Fitting

The "body" of the turnbuckle provides the tension, but the "end fittings" determine how you connect it to the system. Choosing the wrong end fitting is the most common reason for hardware incompatibility in the field.

Here are the four primary turnbuckle types you will encounter:

1. Jaw and Jaw Turnbuckles

The "Jaw" (or clevis) end features a U-shaped fitting with a removable bolt and nut (or pin and cotter).

• Best For : Connecting to fixed eyes, such as hoist rings, pad eyes, or wire rope thimbles.
• Why We Like Them : They are the most secure. Because the bolt passes through the connection point, the turnbuckle cannot slip off.
• Configuration : Typically supplied with a hex head bolt and nut for permanence.

2. Eye and Eye Turnbuckles

The "Eye" end is a solid, closed loop.

• Best For : Connecting to shackles or quick-links.
• Limitation : Because the eye is closed, you cannot connect it to another closed loop (like a pad eye) without an intermediate connector (like a shackle).
• Durability : Very high. There are no moving parts on the end fitting to wear out.

3. Jaw and Eye Turnbuckles

As the name suggests, this is a hybrid. One end has a jaw, the other an eye.

• Best For : Situations where your anchor point is different from your line point. For example, the "Eye" end might attach to a shackle on a wire rope sling, while the "Jaw" end bolts directly onto a structural pad eye.

4. Hook and Hook / Hook and Eye

WARNING : Hook-end turnbuckles are generally NOT recommended for overhead lifting or critical tensioning.

• The Risk: Under heavy load, hooks can straighten out (fail) at a much lower tension than a jaw or eye. Furthermore, if the tension line goes slack, a hook can accidentally disengage.
• Holloway Houston Recommendation : Use these only for light-duty positioning or fencing, never for critical load paths.

5. Stub and Stub Turnbuckles

These ends have no fittings, just solid steel rods.

• Best For : Fabricators who need to weld the turnbuckle directly into a specific structure or machine assembly.

Comparison Table: Selecting Your End Fittings

Turnbuckle Body Styles: Open vs. Closed

Once you have selected your ends, you must look at the body itself.

Open Body Turnbuckles

This is the standard industrial style. The threads are visible through the frame of the body.

• Advantage : Inspection. You can instantly verify that the threads are fully engaged. In safety-critical rigging, this visibility is essential.
• Drainage : Water and debris fall right through, making them less prone to internal corrosion.

Closed Body (Pipe) Turnbuckles

The body is a solid pipe or tube.

• Advantage : The threads are protected from impact and grit. They look cleaner and are often used in architectural rigging.
• Disadvantage : You cannot see how far the threads are screwed in. You must rely on measurement or "stop nuts" to ensure you haven't unscrewed them too far.

Turnbuckle Load Ratings and Safety Factors

You cannot just grab a turnbuckle that "looks big enough." Like shackles and hooks, turnbuckles are rated by diameter and material.

Understanding the Safety Factor

According to ASME B30.26, load-rated turnbuckles are designed with a 5:1 Design Factor.

• This means the Ultimate Breaking Strength is 5 times higher than the Working Load Limit (WLL).
• Example: If a turnbuckle is rated for a WLL of 2,000 lbs, it should not break until at least 10,000 lbs.
• Note: This safety factor allows for shock loading and wear, but you should never exceed the WLL intentionally.

Typical Working Load Limits (Forged Carbon Steel)

Note: These are general industry standards for high-quality forged steel (like Crosby turnbuckles). Hardware store varieties (malleable iron) will have significantly lower ratings.

Product Mention : All Crosby turnbuckles stocked by Holloway Houston are proof-tested and meet or exceed ASME B30.26 requirements. We do not sell "hardware grade" malleable iron turnbuckles for lifting applications.

Turnbuckle Installation and Safety

Even the strongest turnbuckle will fail if installed incorrectly. In our 40 years of inspecting rigging, here are the top three failure modes we see:

1. Insufficient Thread Engagement

This is the most dangerous error. If you unscrew the turnbuckle too far to reach a connection, you might only be holding on by two or three threads.

• The Rule : The threaded end must be screwed into the body by a distance equal to at least 1.5x the thread diameter.
• Visual Check : On open-body turnbuckles, ensure you can see the thread passing the inspection hole or window.

2. Side Loading

Turnbuckles are designed for straight-line pull only.

• If you rig a turnbuckle in a way that bends the body (side loading), you reduce its capacity by 50% or more instantly. The threaded rod will bend, the body will warp, and the threads will seize or strip.

3. Ignoring Vibration (The "Mouse" Rule)

In dynamic applications (like a crane boom pendant or a guy wire in the wind), vibration can cause a turnbuckle to slowly unscrew itself.

• Lock Nuts (Jam Nuts) : Tighten a nut against the body to prevent rotation.
• Safety Wire (Mousing) : For critical or long-term installations, loop safety wire through the turnbuckle body and the end fitting to physically prevent rotation. This is the gold standard for safety.

Critical Safety Note: Never Weld a Forged Turnbuckle

Unless you are using "Stub and Stub" ends designed for welding, never apply heat to a lifting turnbuckle. The heat from welding alters the heat treatment of the forged steel, making it brittle and prone to shattering under load.

How to Choose the Right Turnbuckle

Selecting the right hardware is a four-step process.

Step 1: Determine the Load

Calculate the total tension required. Apply your safety margin.

• Holloway Houston Tip: Always oversize slightly. If your load is 1,800 lbs, don't use a 2,000 lb turnbuckle. Bump up to the next size (usually 3,500 lbs) to account for shock loading and longevity.

Step 2: Choose End Fittings

• Connecting to a fixed pad eye? Use Jaw-Jaw.
• Connecting to wire rope slings with shackles? Eye-Eye is sufficient.
• Need to weld it in place? Stub-Stub.

Step 3: Select Take-Up Length

"Take-up" is the distance the turnbuckle can shorten.

• If you are tensioning a 100-foot guy wire, a 6-inch take-up might not be enough to pull out all the slack.
• Standard turnbuckles offer 6", 12", 18", or 24" take-up. Longer take-up allows for more adjustment but results in a longer device.

Step 4: Verify Material

• Carbon Steel (Galvanized) : The industry standard for outdoor use.
• Stainless Steel : Required for marine, subsea, or food-grade environments.
• Self-Colored (Black) : Usually for indoor or theatre rigging where reflection is bad.

Holloway Houston stocks jaw and jaw, eye and eye, and jaw and eye turnbuckles in carbon steel, stainless steel, and galvanized finishes to suit any environment.

Shop Turnbuckles at Holloway Houston

Whether you are securing a headache ball or bracing a steel building, you need turnbuckles that are traceable, tested, and tough.

Holloway Houston Inc. is the largest single-location rigging shop in the US. We don't just sell hardware; we test it in our ISO 9001 facility. When you buy a Crosby or CM turnbuckle from us, you get the peace of mind that comes with certified quality.

We stock a full range of turnbuckles from Crosby and other leading manufacturers, in jaw-jaw, eye-eye, and jaw-eye configurations. All proof-tested per ASME B30.26.

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