How to Select and Use Turnbuckles

What Is Turnbuckle

 A turnbuckle is a mechanical device used to adjust the tension in ropes, cables, tie rods and other tensioning systems. It is also known as a stretching screw or a bottle screw. It usually consists of two threaded eye bolts, one screwed into each end of a small metal frame, one with left-hand threads and other with right-hand threads.

Use 

Turnbuckles are used widely in countless engineering or construction projects that need cables, rods, etc. joining in a manner that can be flexible, literally by the turn of a screw! One of the great advantages of a turnbuckle is that adjustments in tension can be done in tiny increments.

The common uses of turnbuckles are:

1. in aircraft construction to adjust the tension on the wires bracing the wings,

2. in the shipping industry to tension a ship’s rigging and lashings,

3. in theatres to adjust the rigging on a stage,

4. in piping systems, where the lay of the land may be irregular but can be compensated for by the  flexibility of turnbuckles,

5. and, perhaps the most well-known use, in boxing and wrestling rings to secure the ropes that form the ‘ring’. These turnbuckles have to be hefty ones, some wrestlers stand on them!

The turnbuckle is one of the most essential products manufactured today, it would be difficult to walk along a street and not pass several on the way, for example the telegraph poles we’ve been used to seeing for years all have turnbuckles connecting their wires!

Turnbuckles are used to take up slack and apply tension to a rigging assembly.

They are designed to be loaded in straight pull, inline applications. They come in a variety of types, sizes, and coatings to suit many suspending, tie down, and tensioning type applications.

Turnbuckles are categorized by thread diameter, take up length, and end fittings.

Thread Diameter

Thread diameter refers to the diameter of the threaded portion of the end fittings. Larger thread diameters will have a greater load carrying capacity than smaller thread diameters.

Take Up Length

Take up refers to the total length that the end fittings can screw in and out of the turnbuckle body to take up tension.

To increase the amount of total take-up capability in your system, either choose a turnbuckle with more take-up, or attach 2 or more turnbuckles together, in line.

Tensioning

Turnbuckles can tension assemblies without twisting them up because one end fitting is left hand threaded and the other is right hand threaded. This design feature ensures only the turnbuckle body twists when tensioning.

Sizing Turnbuckles to Other Rigging Components

It is important to note that the working load limit should always be taken into consideration when sizing and matching turnbuckles to other rigging components.

For example, a 1/4”x 4” turnbuckle has a much lower working load limit than ¼” cable or ¼” eyebolt, and the fittings may not connect easily. Up-size the turnbuckle to a size that more closely matches or exceeds the working load limit of the rest of the assembly or a working load limit that meets your loading requirements.

End Fittings

Tianjin Founder offers typical turnbuckles with a selection of 3 different types of end fittings with each fitting having its own purpose, advantages, and disadvanatges.

Eye End Fittings

Eye end fittings are used with other components that can be opened and connect into the eye such as a shackle or quick link. They contain no moving parts and are the most cost-effective end fitting of the three.

Jaw End Fittings

Jaw end fittings are composed of a jaw, bolt, and nut. These are used to connect to other components that cannot be opened, such as an eyebolt or swaged sling eye.

Hook End Fittings

Hook end fittings are used for temporary connections and are easily attached and detached from other rigging components.

We do not recommend hook fittings in situations where tension can unexpectedly release from the turnbuckle as this may cause the hook to dislodge.

Drop Forged vs Formed and Welded

Our galvanized turnbuckles are drop forged.

Our stainless turnbuckles come in both drop forged or formed and welded varieties.

The formed and welded turnbuckles are nearly as strong as the drop forged turnbuckles, and offer significant cost savings. For critical applications that require stainless turnbuckles, the drop forged turnbuckles will offer better long-term reliability due to the end fittings’ elongated design that reduces stress and their superior manufacturing process.

Coating Types

Our turnbuckles are made from hot dipped galvanized steel and type 316 stainless steel

Stainless Steel Turnbuckles

Our most corrosion resistant

Best suited for outdoor applications

Highly resistant to rust

Ideal for use in or near saltwater environments where corrosion frequently occurs.

The best choice when using other stainless steel components.

Installing Turnbuckles

Unscrew End Fittings of the Turnbuckle

Unscrew the end fittings of the turnbuckle so that they are both fully extended. This can easily be done by unscrewing each end fitting one at a time until they are both equally extended.

Attaching Fittings for Jaw and Eye Turnbuckle

Jaw End

Unscrew the bolt from the jaw.

Insert the jaw over the eyebolt.

Then, insert the bolt back into the turnbuckle and fasten it tightly

Eye End

Insert the eye into the opened shackle.

Close the shackle so that the eye is locked into place.

Tension

To tighten the turnbuckle, you can either use your hand, a screw driver, or a wrench to turn the body. Make sure to stop the end fittings from spinning with the turnbuckle body. This will prevent the screws from screwing in unequally. Tighten until your rigging assembly is tensioned to the desired point needed for your application.

Locking and Application Considerations

If your application will expose the turnbuckle to vibration, it is good practice to lock the end fittings from turning by using lock wire. This will prevent unwanted loosening over time.

Your turnbuckle may also be equipped with lock jam nuts to prevent loosening.

These can be used in non-critical applications, but are not recommended for critical applications as they put extra strain on the threads.

Pipe Turnbuckles

For pipe style turnbuckles, a small screw driver or other small diameter type rod can be used to tighten the turnbuckle. Insert it into the hole in the body of the turnbuckle and turn to the desired tension.

Turnbuckles and their configurations simply offer a solution to a specific challenging lifting scenario. With any rigging or lifting selection, all the rigging is determined by the pieces of equipment that need to be lifted and by its other factors including headroom challenges, confined spaces, or any restrictions in moving a load or having offset center of gravity, as well.

For example, should you need to elevate something to four feet, your options are installing four, five, or six shackles in a line depending on the size of the shackles to make up the difference or you can install one turnbuckle and adjust it accordingly.

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