Prolyte Campus Blog: Bridle - Getting it Right

The word ‘Bridle’ is used in entertainment rigging, but it sounds like a fusion between ‘equestrian’ and ‘relationship’ topics. As mentioned in the previous blog, it is all about “getting the knot tied right”. But let’s not be tied down for now, and have a closer look at the actual equestrian reins that get together — taking one more step in leaving the soft equestrian world and step into the ‘hard steel’ environment.

If we talk about bridles, we talk about rated components, sling angles, forces and capacity limits - and/or safety factors. If we want - or are required - to avoid bridles, we must use lifting beams.

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Components

Our bridles are for 99% made up of:­­

1) Steel Wire Rope slings: The bulk of which are generally called ‘1 tonne’, however, the true WLL will often be 10-15% higher. They mostly are found in a diameter range of 9,5 - 10mm and standard lengths range from 0,5m (‘dog bone’) to 10m (or more). Such wire rope slings can be terminated in a thimble or a soft eye, but when it has a thimble, make sure it is an oversized one, where the ears of 3,25 t shackle will fit through. There are also wire ropes that are equipped with a hook on one side. These are often referred to ‘Basket Steels’ or ‘Quick / Click Baskets’ and are used where they need to go around a steel beam. Quicker and safer than using a basket with an additional shackle.

2) Anchor Shackles: Forget about D-shackles! The vast majority used in our business will be 3,25 tonne in WLL. They can take quite some abuse when used in combination with 1-tonne hoists and 1-tonne wire ropes.  (I am not going to refer to the American way of calling shackles by size, rather than capacity. The continuous increase of steel alloy qualities will make that reference type to become obsolete within a decade or two)

3) Clutch Chain slings and/or STAC® or ‘Deck’: The Clutch chains are generally smaller in size, more accurate and more versatile, but more expensive. They are usually in WLL 1 tonne, 1,5 tonne or 2 tonnes. The Deck & Stac long link chains are around 4,5 to 5 tonne WLL, but officially not allowed - in the EU - for lifting purposes in the way defined by the Machinery Directive. Use for long link chain in the entertainment industry is accepted as a structural element loaded only in straight pull. For special applications, e.g. bridles, long-link chains may be used, in conjunction with shackles, to adjust the length of a leg, provided the load-bearing capacity of the chains is known.

4) Master-Link or Pear Links: Depending on their purpose in ranges from 1,5 up to 5 tonnes WLL. Doing 3-way bridles is a master-link job. Just as doing dead-hangs, or secondaries is becoming much more manageable with such significant links.

5) Soft Steels (or Steel Flex or GAC slings): These exist for about two decades. In a historical context, we might still think in round slings (‘spansets’) and K-links, but the general rule is avoiding the use of high-temperature sensitive textile lifting components. The high-temperature hazards come from various sources that we provide ourselves in this business: -pyro, - lasers, - hothouses of general lighting fixtures, - high energy beams of the newest range of movers.

And Carabiners? Quick Links?
In bridles? Only in your back yard, but not on a professional rigging job.

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Thank you for your knowledge and huge experience

Gleb Kharchenko MF Group, Russia