Recovery Bridles (Equalising Straps) and understanding Sling Loads

[the evil twin]

At the request of others...

Recovery Bridle - A recovery bridle is a rope, cable or webbing strap attached to both sides of the vehicle being towed or winched. It allows for relative movement on the winch wire, tow rope or snatch strap to deflect from side to side allowing the towing vehicle and the vehicle being towed independence of movement

Equalising Strap (ES) versus Tree Trunk Protector (TTP) - An ES is specifically made for use as a bridle and is usually two layers of webbing sewn together with a wear protection sleeve for the area where the Snatch Strap is attached. A TTP is usually one length of webbing and often does not have the wear protection necessary for prolonged towing. TTP's can be used as bridles but some protection should be considered at the Snatch Strap attachement area.

My Recovery Bridle (or Equalising Strap if you prefer) is a short length of 25MM Dyneema Rope I have eye spliced myself with a breaking strain just short of a space shuttle launch

Here is one of the best I have ever seen and puts my home made jobbie to shame. Note the blue 'anti recoil' straps in case of a rigging component failure

[the evil twin]

Sling Load Angle is the angle the legs of the sling form against the direction of the applied force.

Many people assume that as soon as an ES or Bridle is introduced then the applied force is halved and transmitted equally to the attachment points IE 1000 KG from the Snatch Strap will be seen as 500 Kg at the left attachment point and 500 Kg at the right attachment point of the ES.

If the angle formed between the front of the vehicle and the legs of the strap is 60 degrees or more (as in the piccy above) this is true and a 1,000 Kg force will appear as 500 Kg's at each attachment point.

If the ES was shorter and the angle formed decreases to 45 degrees the the 1,000 Kg force will be seen as approx 700 Kg's at each attachment point... as the angle decreases the load increases and past 60 degrees is as much as 90 % or 900 Kg's

Now, this is all pretty heavy sh1t that is the life blood of riggers etc and hats off to 'em but I prefer a simpler life so I look at it this way...

Pretty much only two things can go wrong, either a) the sling angle goes pear shaped OR b) one leg lets go and everything else stays attached. In either case the Max Load on an attachment point is now the recovery force (1,000 Kg in our example) so I rig it that way and pretend the bridle is of no assistance in sharing the load whatever

Remember the original definition and purpose of the Recovery Bridle
"allows for relative movement on the winch wire, tow rope or snatch strap to deflect from side to side allowing the towing vehicle and the vehicle being towed independence of movement"
The fact that it also has the side effect of reducing the load at the attachment points should not necessarily be relied upon

[Silver]

I look to the bridle to apply some of the winching or snatching force to both chassis rails, rather than one.

[Silver]

I almost want to get stuck now ;-) After looking at the dissy wiring to answer Evil's post I hooked up my 2.5m equaliser/bridle to the new hooks on my new recovery plates. Nice narrow angle and it even loops nicely around the bullbar without obstructing number plate or lights. There is room for improvement - the wear sleeve is actually a red plastic flag looking thing. Supercheap..... Will need to do something about that. the bridle itself and the stitching look ok. Plan to give it a test on the neighbour's mango tree. too chicken to give it a work out on a telly pole. If it fails the mango tree will cop it, and hopefully produce more fruit :-) The mango tree is a good and faithful assistant. It and a chain and judicious use of low range helped reshape the barn door after spouse backed into a post. Now to be fair, I have also backed into a post. However I was lucky enough to dead centre it with the tow bar, not the spare wheel :-)

[Bob]

Good informative Post Thanks

[DX grunt]

Hey ET.

Where do you buy that bridle from in WA?

Rossco

[Bacho86]

I recently saw a 10mm dynamic bridle recovery kit with shackels and all for $102 in Outback 4WD in Bayswater, VIC - not that it helps you Rossco, sorry mate.

[the evil twin]

Hey ET.

Where do you buy that bridle from in WA?

Rossco

It is made right here in WA, Roscoe (a real honker isn't it).

The 4WD recovery kit they produce is the absolute Bees Knees, wish I'd found 'em before I got all my gear... altho I might be tempted to get a kit and sell off most of my stuff

They look after the Mining Industry and make Snatch Straps, Bridles etc and Recovery Kits for vehicles up to 100 tonnes

I am trying to get a sample along to a club night ( of the Patrol Kit not the 100 tonner but bringing one along for a giggle would be hilarious)... I'll keep you posted. Will know more directly after Easter

[Shaun 4x4]

I know this is an old old old thread but I want that bridal strap. What brand and where do I get one?

[Shaun 4x4]

Still waiting for answer?