joining wire ropes

[Vicks]

hi guys,

I have a set of towing ropes, two 4mtr 10mm wire ropes and one 6mtr 2" wide tow strap. I have only done three, simple tow recoveries till date and no snatching.

I have a few questions...

1. I have read the document which shows the correct and in-correct methods of joining snatch straps. Applying the same methods to a wire rope, i have the below two different options.

Option1: wire ropes joined as recommended, with an object to prevent the two binding together (hammer for illustration purposes only). My observation here is there might be excessive stress at the hooks & the U-bolts when towing.



Option2 : I feel this one is a better way of joining the two wire ropes. The hooks are of equal dimensions and will apply equal amounts of force on each other while towing, while providing safety in case one of the joined hooks snap. No forces applied on the U-bolts.





2. How do wire ropes behave while snatching. Yes, i understand that each snatch is different, but lets take a scenario when a 2ton vehicle is bogged in soft sand, axle deep, flat terrain (no incline/decline), sand removed from the front of the wheels. If i were to use the 10mm 4ton rated tow rope to snatch it at a speed of say 20kmph ?

cheers

[peanut]

From a riggers perspective please dont. The WLL of that wire if it was a rated wire would be about 800 kg, factor in the way it is clamped and it would drop down. Shock loading it would be miles above the breaking point.

[Onslow]

Vicks,

Please don't use wire cable for a snatch recovery! Wire isn't designed to handle a shock load, and neither are those hooks. They are both rated for a static load only. Furthermore, if anything was to break (which is a very high posibility with this set-up) it could be extremely dangerous to the driver and any onlookers! The only equipment to use is a properly rated Snatch Strap and rated shackles, together with rated recovery points on your vehicle.

[Fro]

Again, don't do it, ever. If something breaks you have metal hook that is going to be moving through the air with the potential to damage a vehicle or worse, hurt someone.

Just spend a few dollars and buy a proper snatch strap, maybe two if you need to put some distance between the vehicles because of the terrain or obstacles.

[Stevie-Ray]

It'd be funny if it wasn't so dangerous...!

It'd be funny if it wasn't so dangerous, especially the 1st method. When, not if, the hooks breaks, you'll have missiles on wire-cable shooting back at both vehicles, & God knows what or who the claw-hammer would end up embedded in!

Cheers

[Vicks]

From a riggers perspective please dont. The WLL of that wire if it was a rated wire would be about 800 kg, factor in the way it is clamped and it would drop down. Shock loading it would be miles above the breaking point.

Thanks for the numbers peanut.

Vicks,

Please don't use wire cable for a snatch recovery! Wire isn't designed to handle a shock load, and neither are those hooks. They are both rated for a static load only. Furthermore, if anything was to break (which is a very high posibility with this set-up) it could be extremely dangerous to the driver and any onlookers! The only equipment to use is a properly rated Snatch Strap and rated shackles, together with rated recovery points on your vehicle.

Again, don't do it, ever. If something breaks you have metal hook that is going to be moving through the air with the potential to damage a vehicle or worse, hurt someone.

Just spend a few dollars and buy a proper snatch strap, maybe two if you need to put some distance between the vehicles because of the terrain or obstacles.

OK guys, i got the message loud and clear. No snatching with wire ropes.

So, is the option2 i mentioned above OK for towing ? I say towing, not snatching, in case i need to have an extended towing rope ?

It'd be funny if it wasn't so dangerous, especially the 1st method. When, not if, the hooks breaks, you'll have missiles on wire-cable shooting back at both vehicles, & God knows what or who the claw-hammer would end up embedded in!

Cheers

Hi stevie,

The claw hammer is for "illustration purposes only" as i mentioned in the original post. Hope that clarifies.


Thanks for all the inputs guys. Now time to go get a set of dedicated "snatch" straps as all i have is the tow rope (wire and strap) at the moment.

[rebelone607]

See little or no problem connecting the ropes as shown in option 2 ie. hook to hook or hook to eye as that is basically how you would attach a winch or crane cable to a lifting sling. Never hook the "hook" around the cable as in option 1 as that will put a permanant kink in the cable dramatically weakaning them. There have been many times in my carer as a rescue officer where we have had to join cable to cable to obtain the reach we needed during winching operations. You will notice that I said winchining operations as it would have to be desperado stuff to consider using cable in a snatching or towing operation, the risk of shock loading is too great. Having said that I have had one occasion where we had to retrieve a vehicle bogged on a beach with a rising king tide, the nearest we could get to it was nearly 100 meters so we just had to use the one 50mtr x 12mm f.s.w.r. we had which was then connected to our tow strap connected to the snatch strap, this built a dynamic component into what was otherwise a static system. As many heavy potato sacks and jackets etc. as we could lay our hands on were placed at intervals along and over the cable, fortunately the recovery was successful and incident free. I must stress that this operation was undertaken by rescue personel with an enormous amount of experiance in roping and winching operations.
Merv

[mrbitchi]

I'd only use method 2 for a straight pull scenario, not for towing as in towing a vehicle down the road for a distance, as this could place shock loads on the rig that's it's not designed for as vehicles speed up and slow down..

[Ballfyboy]

I would just use one hook and hook it into the loop on the second cable leaving one hook to hang down doing nothing. The reason for this is that when under load the system is in a straight line. This will be the strongest and is how most things are engineered to work. It does not take much of a twisting/torqueing action to add huge stresses to systems.

Good to see you have taken the snatching comments on board. The reason for the 'hammer' to be placed between the snatchstraps is that they will compress and bite together and you will forever have one strap from that time on. Cable will not do this. Also your little bulldog clamps will be the weakest link I would think.

[Calspec]

I would also strongly reccommend the use of a thimble and a second bulldog clamp in each of those hook attachments.

[NTPaj]

Calspec,

You took the words right out of my mouth. Thimble is required and min 2 Wire rope grips.

The wire looks like 6mm, if Fibre Core SWL is around 340kg (from memory).
8mm Fibre Core has a 550kg SWL
8mm Steel Core has a 780kg SWL.

All have a 5 times WLL safety factor.

Woody