Using a towball for recovery

rgren2 · Guru

Using a towball for recovery

Peter_n_Margaret · Guru

NEVER use a tow ball for any recovery using any method, EVER.
A non stretch strap is harsher than one that stretches, but a stretchy snatch strap can provide any force from mild to extreme depending on how it is used.
Used with knowledge, training and care a snatch strap is a very useful tool.
It can be put into the hitch itself and secured with the hitch pin, with care.
Cheers,
Peter

rgren2 · Guru

People who flat tow use the towball, a lot of jerky motion happens there.

bratboy · Veteran Member

There are plenty of other option , as Peter said remove the tongue and use the hitch pin BUT never never never use the towball , as a matter of fact I don't believe towballs should be used for anything above a garden trailer .

PeterD · Guru

rgren2 wrote:
People who flat tow use the towball, a lot of jerky motion happens there.

The coupling fit on the tow ball may be a bit slack. However, the force on the ball by the rattle will be very fare less than the shock from a tow rope or snatch strap becoming tight when you race forward and take up the slack.

rgren2 · Guru

rgren2 wrote:
It is a well known topic to never use the towball for a snatch recovery, but, a snatch recovery doesnt always mean a twenty meter run up. Just a gentle forward move should be sufficient. If a snatch strap was not to be used, just a normal recovery strap with no kinetic energy, would not the forces be the same as if a hitch were used?

Gentle forward move. Not talking about the mad run up.

oldbloke · Guru

rgren2 wrote:
People who flat tow use the towball, a lot of jerky motion happens there.

Yes, agree. Should be ok IMO subject to careful/mild use. If you snatch like you see some gooses do on YouTube the ball would most certainly be getting over loaded. They are rated 3t to tow, not yank on it with 3t or more.

However, seems to me the tow pin would be a better option.

Best option is don't get bogged. That's why I got a 4x4. Lol

Aus-Kiwi · Guru

Yes just use the bumper much stronger
! Sarcasm here people .,

elliemike · Guru

DONT DO IT.

TOW BALL.jpg

-- Edited by elliemike on Saturday 7th of May 2022 12:24:01 PM

jegog · Senior Member

I don't think many tow balls are fixed at the correct tension.
Just as tight as can be achieved with the biggest shifter or stillsons.
The WDH I bought stipulates the torque for all the nuts including the tow ball.

yobarr · Guru

jegog wrote:
I don't think many tow balls are fixed at the correct tension.
Just as tight as can be achieved with the biggest shifter or stillsons.
The WDH I bought stipulates the torque for all the nuts including the tow ball.

That's right Dennis, and this can be the result. Cheers

rgren2 · Guru

Both pictures confirm that it is the shank of the towball that has failed.
Now, what could cause a large threaded shank to break like that, shear forces on a stretched piece of metal?

Mike Harding · Guru

I suppose (is there a mechanical engineer in the house?) that a tow ball and caravan are, essentially, moving at the same speed and it is only when the caravan lags the car by the play in the hitch that a shock load occurs? This lag distance will be, say, 5mm so the difference in speed (inertia?) of the van/car will be minimal - it is not as though the car doing, say, 30kph suddenly has a caravan hooked on its towball.

Personally I don't like towballs as a hitch mechanism and I don't like snatch straps and given how easy it is to use the pin rather than the towball I'd always go that way - a towball is 500gm of solid shot heading your way fast!

I don't mind risk taking but why do it if you don't have to?

dogbox · Guru

Mike Harding wrote:

I suppose (is there a mechanical engineer in the house?) that a tow ball and caravan are, essentially, moving at the same speed and it is only when the caravan lags the car by the play in the hitch that a shock load occurs? This lag distance will be, say, 5mm so the difference in speed (inertia?) of the van/car will be minimal - it is not as though the car doing, say, 30kph suddenly has a caravan hooked on its towball.
Personally I don't like towballs as a hitch mechanism and I don't like snatch straps and given how easy it is to use the pin rather than the towball I'd always go that way - a towball is 500gm of solid shot heading your way fast!
I don't mind risk taking but why do it if you don't have to?

The next person to suffer grievous harm as a result of a tow ball failing while being used as a recovery point ,will not be the first or last

Peter_n_Margaret · Guru

The lateral (forward and back) load rating required for the tow bar is 2 x its tow rating. The towball requirement is probably similar, but they do break when used for recovery.
Cheers,
Peter

yobarr · Guru

Peter_n_Margaret wrote:
The lateral (forward and back) load rating required for the tow bar is 2 x its tow rating. The towball requirement is probably similar, but they do break when used for recovery.
Cheers,
Peter

Simply leverage at work. Cheers

jegog · Senior Member

Mike Harding wrote:
I suppose (is there a mechanical engineer in the house?) that a tow ball and caravan are, essentially, moving at the same speed and it is only when the caravan lags the car by the play in the hitch that a shock load occurs? This lag distance will be, say, 5mm so the difference in speed (inertia?) of the van/car will be minimal - it is not as though the car doing, say, 30kph suddenly has a caravan hooked on its towball.
Personally I don't like towballs as a hitch mechanism and I don't like snatch straps and given how easy it is to use the pin rather than the towball I'd always go that way - a towball is 500gm of solid shot heading your way fast!

I don't mind risk taking but why do it if you don't have to?

All the rivets in the Commet jet planes were moving at the same speed as the rest of the plane and yet they failed.

Pure and simple metal fatigue was the culprit. Same with tow ball shanks. Tighten the nut too much and all those small shocks from potholes and corrugations advance the metal fatigue

jegog · Senior Member

yobarr wrote:
jegog wrote:
I don't think many tow balls are fixed at the correct tension.
Just as tight as can be achieved with the biggest shifter or stillsons.
The WDH I bought stipulates the torque for all the nuts including the tow ball.
That's right Dennis, and this can be the result. Cheers

Classic metal fatigue photo.

yobarr · Guru

Here we have what I believe is the best hitch of all, a DO35, and it is clear that this example has had some very strong forces applied. Didn't break though. Cheers

oldbloke · Guru

Since the circumstances of the damage are not known, it is a pointless pic and even more pointless statement to say they are "best."

To make any reasonable assessment or comparison with other hitch designs enginerting/laboratory tests would be required.

iana · Guru

Love to have more info on the Comet rivets failing. Sounds a tall one to me!

Plain Truth · Guru

iana · Guru

Yes, the squarish windows meant stress points at each corner, putting in round windows fixed the problem, nothing to do with rivets.

-- Edited by iana on Sunday 8th of May 2022 08:33:40 PM

Sarco Harris · Senior Member

A friend used the pin from his tow ball goose neck to to a straight short tow out of a bog hole. In total moving the towed vehicle only 2 metres, no jerking etc. just a straight slow steady pull.

The result was a bent pin, which then meant he could not easily remove it an refit his goose neck and then tow is camper trailer from the Vic high country.

Long story short, day trip into Bainsdale, new pin, old one cut out (a reciprocating hacksaw I believe was used) and then back into camp.

I suggest simply spend some dollars and buy the proper recovery eye to fit into the towbar, a quality rated shackle and be done with it, and include a spare pin in your kit.

jegog · Senior Member

Plain Truth wrote:

According to a University of Birmingham paper

"A further 1826 simulated cycles were completed before fatigue failure of the pressure cabin from a crack growing from a rivet hole at the forward port escape hatch"

https://www.fzt.haw-hamburg.de/pers/Scholz/dglr/hh/text_2019_01_24_Comet.pdf

Mamil · Senior Member

Why not - what could possibly go wrong?

Recovery using towball.jpg

Aus-Kiwi · Guru

I use a a number 8 around tow bar when using strap or rope . I would never use the ball on its own !! ( can become a sling shot ) I think we have inferior imports these days . No one is really checking quality !! We have used this method to pull transmission / power cables through valleys etc .

Whenarewethere · Guru

A few years ago when I towed a truck bogged with 3 tonnes of roof tiles. It actually had a front tow ball. I still used the towing eye.

Just looking at tow ball design, it is simply not designed for massive horizontal stress.

When I bought my towing ropes from ARB they came with comprehensive safety information. It's worthwhile reading to avoid decapitation.

PeterD · Guru

Aus-Kiwi wrote:
I think we have inferior imports these days . No one is really checking quality !!

Tow ball projectiles have been a problem for over 50 years. It has nothing to do with declining quality.

oldbloke · Guru

Bit surprised the tow pin gave up so easily.

When you look at a ball it looks very strong, but just not designed to take that amount of force/stress. Also the metallurgical strength of the material would be a factor including fatigue.

I wonder if you removed the ball and used the hole on the tongue if it would be ok with a decent shackle??

We need a mechanical engineer on this forum.