recovery from the towball.. (only if you have to)

**DEFENDERZOOK** · 23rd February 2010, 07:34 PM

Originally Posted by isuzurover

So you carry a tow rope AND a snatch strap???

no......not really.......

i have done a big no-no as far as snatch straps are concerned.....and towed a vehicle or two back onto the road......
a snatch strap isnt designed for constant forces......its only designed for a quick stretch and release.....

i dont have a tow strap as such......but i do have a tree trunk protector.....which i could probably use.......
but i would rather abuse my snatch strap......it has a bit of give and feels a bit safer......
and its also due for replacing......it has been used about 8 or 9 times.....
and ive heard they are really only meant to do about half a dozen recoveries.....

but i once recovered some idiots on some sand who knew their centre diff wasnt working......but still were out there anyways.....
they didnt have any recovery points......so i had to pretty much loop it around some part of their towbar......and it damaged the edge of my strap......

i was very tempted to leave them there.....but they had kids with them....and it was getting dark.......

**twitchy** · 23rd February 2010, 07:44 PM

Originally Posted by weeds

first question i would ask is.....whats the rope rated too?

diameter squared = rough guide for SWL.

**Blknight.aus** · 23rd February 2010, 07:57 PM

for natural fiber rope....

for bonus money whats the mulitplier for synthetics that float (and sink if you know it)

**Dougal** · 23rd February 2010, 08:01 PM

Originally Posted by PAT303

Has anyone actually seen a tow ball snap off?. Pat

Not me. But I have heard the wives tales.
Some lightweight towballs (i.e. fitted to cars, not 4wd's) have a shank of about 3/4" max, take the threads into account and you're down to about a 15mm core.

I remember seeing one old towbar that was actually just a ball shaped sleeve which a coach bolt passed through.

Regarding the ratings of tow-bars.
I've designed truck towbars before and the rating for those is in compression. The idea being the towbar must handle a hard stop of 1g (i.e. the entire towed weight) acting forwards and down at a 20 deg angle, the maximum material stress is also specified but I can't remember exactly what right now, but it's similar to the stress that will withstand 1,000,000 cycles fatigue.
So your one-hit factor of safety is about 3 before it will bend if all is good.

Most 3,500kg rated 4wd towbars I've seen would not meet the standards for 3,500kg on a truck. The tongue needs to be quite heavily gusseted to withstand the bending stress applied.

**twitchy** · 23rd February 2010, 08:25 PM

Originally Posted by Blknight.aus

for natural fiber rope....

for bonus money whats the mulitplier for synthetics that float (and sink if you know it)

Rope types are diameter squared times the numbers below.
Nylon x 2.25
Polyvinyl x1.25
Polyethylene x1.45
Manila x1
Polypropylene x1.6
Polyester x2
Silver x1.16
Sisal x1.0

Thread: recovery from the towball.. (only if you have to)

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