Turnbuckle

What is a Turnbuckle?

A turnbuckle is a piece of hardware used to eliminate slack and adjust tension in a rope, cable, or other tensioning system.

ASME B30.26 – Rigging Hardware defines a turnbuckle as “an adjustable device consisting of three primary components: a body, a right-hand threaded end fitting, and a left-hand threaded end fitting.”

The end fitting on either side of a turnbuckle connects to the tensioning system and/or a securement point. The turnbuckle is then tightened or loosened to adjust tension and eliminate slack in the cable or rope is it connected to.

A turnbuckle may be used on its own or in conjunction with other turnbuckles to increase length in the assembly.

Important Parts of a Turnbuckle:

End Fittings: these are the two connection points that screw into the opposite ends of the turnbuckle body. One end fitting is right-hand threaded while the other is left-hand threaded. This allows you to turn the body to adjust tension after installation without moving the end fittings.

There are three main types of end fittings that can be used together in any combination on either end of the turnbuckle:

• Hook end – a hook end fitting is used to create temporary connections because they are easy to quickly connect and disconnect. They should never be used in connections where tension could unexpectedly release.
• Jaw end – a jaw end fitting consists of a jaw and bolt secured together by a nut or a pin. These are used to connect to components that cannot be opened, such as an eye bolt.
• Eye end – an eye end fitting is a closed loop that can be connected to a shackle or quick link.

Thread diameter: this is the diameter measurement of the threaded portion of the end fittings. The greater the thread diameter is, the greater the load-bearing capacity of the turnbuckle and vice versa.

Take-up length: this is the total length that the end fittings can screw into and out of the body to “take up” tension. Take-up length can be measured in terms of “opened” or “closed” end fittings: the end fittings are either fully extended or fully retracted.

Types of Turnbuckles

Turnbuckle types are, essentially, named for the combination of end fittings used in the device. The most common end fitting combinations are:

• Jaw and jaw
• Eye and jaw
• Eye and eye
• Hook and hook
• Hook and eye

Common Uses for Turnbuckles

As mentioned above, turnbuckles can be used with a length of rope, cable, or other rigging assembly as a connection point to adjust slack and tension within the line.

Turnbuckles can be used for something as simple as a fence or as complicated as a suspension bridge. Some industries that commonly use turnbuckles are:

• Sports and entertainment – turnbuckles are used to act as a securement point and to create tension in the ropes surrounding a wrestling or boxing ring. You can’t see them, of course, since they are covered in soft material for the athletes’ safety!
• Maritime transport – turnbuckles are commonly used to tension a ship’s lashing and rigging components.
• Construction – turnbuckles are often used to provide tension support for suspension bridges, large buildings, and highway guardrail cable assemblies.
• Aviation – cables and wires present within the construction of an aircraft—wings, flight control systems, etc—are tensioned by turnbuckles.

Material: Galvanized/ Drop Forged vs. Stainless Steel Turnbuckles

The most common turnbuckle materials are galvanized and stainless steel. Choosing between these two materials is important if factors like price and corrosion resistance are important to you.

Stainless steel turnbuckles are ideal for use in outdoor and saltwater environments, as they are extremely resistant to rust and corrosion. If corrosion is a concern, stainless steel is likely the best choice for your turnbuckle material.

Galvanized/ drop forged steel turnbuckles are cheaper than stainless steel and can also be used in outdoor applications, but with caution, as they are not as resistant to corrosion as stainless steel turnbuckles.

Turnbuckle Inspection and Removal From Service Criteria

During the course of a turnbuckle inspection, remove it from service if any of the conditions listed in ASME B30.26 – Rigging Hardware are present:

• Missing or illegible identification
• Indications of heat damage, including weld spatter or arc strikes
• Excessive pitting or corrosion
• Bent, twisted, distorted, stretched, elongated, cracked, or broken load-bearing components
• Excessive nicks or gouges
• A 10% reduction of the original or catalog dimension at any point
• Excessive thread damage or wear
• Evidence of unauthorized welding or modification
• Other conditions, including visible damage, that cause doubt as to continued use

We stock and distribute turnbuckles in a variety of different configurations and sizes in both galvanized, drop forged and stainless steel. We can supply both daily use models as well as premium ones from Crosby.

If you require further advice on selecting the most suitable turnbuckle for your needs, please contact one of our Lifting Specialists today.