Turnbuckles: Devices Used to Adjust Tension
Turnbuckles are connecting fittings used to create or relieve tension on wires, ropes or chains. A turnbuckle is required so that the cables are not twisted around as tension is adjusted.
Turnbuckles can also be referred to as stretching screws or bottle screws. True to its name, turnbuckles are basically buckles that turn. These are mainly used when increasing and reducing tension on ropes or cables are needed. It does the job without having to twist the ropes and cables that it is connecting.
A turnbuckle is a three-piece coupling device that is made of metal. The main body is usually rectangular or oblong in shape which has internally threaded holes at both ends. The other two parts consist of two threaded inserts which can have an eye, stub, hook or jaw on the threaded end.
Size and use
To increase or decrease tension, the body is turned and screws are drawn towards the center. This is how the tension increases. Doing the opposite reduces tension. This device is used in many different applications that require a lot of tension.
Their sizes vary depending on their use. A turnbuckle used for structures like buildings and suspension bridges can weigh hundreds of pounds. Thin cables for garden fences make use of smaller ones and these weigh very little. Matching the size of the turnbuckle and the apparatus where the tension is needed is the key. Each component is “Load Rated”.
These devices are also widely used on flexible cables in flight control systems. Biplanes tend to use turnbuckles for adjusting the tension on wires that brace their wings. In fact, many World War I aircrafts can be seen with rigged cables and turnbuckles.
Ships and boats also make use of turnbuckles. These are available in various sizes. When used in ships, these are usually called bottle screws. These are used for adjusting the tension on a ship’s lashings or rigging.
Turnbuckles are used for many construction purposes. Aside from suspension bridges, suspended ceilings also make use of these devices. These can also be seen on screen doors to keep them from sagging or drooping.
These are also used as safe structural connections between different precast components. Using these can make mounting precast concrete much faster.
In the entertainment industry, these are used for all types of rigging in theatres, live concerts and films. Most of the time, these are used for adjusting the length of the rope or cable for backdrops, curtains and other such effects.
These devices are also usually seen on boxing or wrestling rings. These make sure that the ring rope’s tension is just right. It connects the ring ropes and ring posts. These turnbuckles are made to withstand a fair amount of force especially in wrestling rings. Some wrestlers tend to slam against the rope and some even jump from it.
As an added note, deformed turnbuckles should not be reused. Trying to apply heat and re-shaping it reduces the turnbuckles’ strength. Turnbuckles should be as strong as the cable or rope that they are attached to.
These should also be used properly and with caution. Due to high tension on some applications, sudden release of tension can cause the cable or rope to flail about. It is important to put some slack on the rope or cable prior to removing it.
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