Broken tow ball

Submitted: Sunday, Jul 21, 2013 at 17:31
ThreadID: 103345 Views:6065 Replies:11 FollowUps:28
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Recently retired we have purchased a 2013 Isuzu Dmax Crew cab. We have purchased many extras including a tow kit with ball. After towing from mid North Coast to Beau Desert over Mount Lindsay (in the Rain) the ball broke. Luckily for us it broke as we were leaving Beau Desert caravan park the next morning. Has any one else lived to tell this story? We are very safety conscience and R and M is up to date. The dealer is looking into this near miss as I type.
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Reply By: dieseltojo - Sunday, Jul 21, 2013 at 17:41

Sunday, Jul 21, 2013 at 17:41
That's not a good tow ball surely . Did it have a 3.5 ton stamp on top of the ball.

Either way I replace my tow ball at least every 5 years. Also, I check the bolts in the hitch area and bar fixings.
AnswerID: 515134

Follow Up By: net J - Sunday, Jul 21, 2013 at 20:46

Sunday, Jul 21, 2013 at 20:46
Hi dieseltojo,
I am not sure or the tonnage of the broken one but the new one is 3.5 ton.
The kit was new in January 2013.
Hubby is very meticulous with our safety and has a 10 point check every trip. Maybe Mt Lindsey made it lose?
FollowupID: 794287

Reply By: Notso - Sunday, Jul 21, 2013 at 17:53

Sunday, Jul 21, 2013 at 17:53
I've heard of it happening. The important thing is to ensure you buy a load rated ball. I suppose it is possible to have a faulty unit even though it carries a load rating. Maybe find one not made in China! If that's possible.
AnswerID: 515136

Follow Up By: Member - Boo Boo (NSW) - Sunday, Jul 21, 2013 at 18:13

Sunday, Jul 21, 2013 at 18:13
Can you let the forum know the result of their investigation into the tow ball failure.


FollowupID: 794279

Follow Up By: Notso - Monday, Jul 22, 2013 at 12:12

Monday, Jul 22, 2013 at 12:12
Lord knows? It happened outside a caravan park where I was staying. I just helped out the traumatised couple while it was sorted out.
FollowupID: 794324

Follow Up By: Lyn W3 - Monday, Jul 22, 2013 at 13:48

Monday, Jul 22, 2013 at 13:48

So you were there when it happened, perhaps you could shed some more light on what did happen.
FollowupID: 794332

Follow Up By: Notso - Monday, Jul 22, 2013 at 15:22

Monday, Jul 22, 2013 at 15:22
The ball broke at the very top of the shank right under the flared flange.

From what I could see it looked like a clean break.
FollowupID: 794343

Follow Up By: member - mazcan - Monday, Jul 22, 2013 at 16:03

Monday, Jul 22, 2013 at 16:03
hi notso
thanks for clearing that up the op stated it broke off on the neck of the ball which is just under the ball head
but now you have stated that it was the shank that snapped just under the flange that sits on the top of the tow tongue which is a totally different situation
that may have been caused by a spring washer breaking and dropping out as mentioned by axle and self allowing the shank to slop around in the hole and would/cause it to snap the shank

net j was sure lucky he wasn't up to full speed out on the rd when it broke
FollowupID: 794346

Follow Up By: Notso - Monday, Jul 22, 2013 at 16:20

Monday, Jul 22, 2013 at 16:20
Two different events, the one I am referring to occurred about 3 years ago.
FollowupID: 794349

Reply By: Member - Phil G (SA) - Sunday, Jul 21, 2013 at 18:16

Sunday, Jul 21, 2013 at 18:16
Where did it break?
Could the nut have been loose?
AnswerID: 515139

Follow Up By: Rockape - Sunday, Jul 21, 2013 at 18:24

Sunday, Jul 21, 2013 at 18:24
I will ask the same as what Phil has asked. I checked my ball before we left and found the spring washer had flattened and was poking out on side. If this had been left, failure would have occurred.
FollowupID: 794280

Follow Up By: net J - Sunday, Jul 21, 2013 at 20:51

Sunday, Jul 21, 2013 at 20:51
HI Phil,
The ball failed at the neck of the ball. It was like it had been cut with a knife. The nut could have worked loose I guess.
FollowupID: 794288

Follow Up By: fisho64 - Monday, Jul 22, 2013 at 00:33

Monday, Jul 22, 2013 at 00:33
if it was at the neck of the ball it would have little to do with the thread or nut.
Metal fatigue?
FollowupID: 794295

Reply By: Axle - Sunday, Jul 21, 2013 at 18:34

Sunday, Jul 21, 2013 at 18:34
G/day Net J.

Maybe it had the thread taken to far up the shank which will weaken it considerably.

I reckon they should be made like a tapered ball joint or tie rod end joint.

Glad nothing serious happened.

Cheers Axle,.
AnswerID: 515142

Reply By: Ross M - Sunday, Jul 21, 2013 at 18:49

Sunday, Jul 21, 2013 at 18:49
net J

As others have asked, where did it fail. This is important.

The threaded shank?
At the top of the shank where it becomes the flange?
In the curve of the neck where it begins to become a ball?

Does your tow tongue have a flat top and bottom or is the hole in the tongue raised a bit at the edges of the hole and it angularly stresses the shank when tightened?

To be safety conscious is a good thing, but if there is an underlying problem which you don't see then safety can be severely compromised.

Many tongues are hole punched and the upper or lower surface is not flat an cannot seat the ball flange properly no matter how tight you do the nut tension.

There are lots of reasons why it may fail.
Faulty ball metallurgy also is possible.

Not sure how a dealer can ID the cause?

Ross M
AnswerID: 515143

Follow Up By: member - mazcan - Monday, Jul 22, 2013 at 12:43

Monday, Jul 22, 2013 at 12:43
hi ross m
net j clearly said is broke at the neck of the ball that means just under the ball, however net j didn't seem to clear on whether the nut was loose at the time of the break which should have been fairly obvious had he taken a close look imho

I had one do the same years ago on the farm in my case the spring washer popped out from under the nut letting the thread shank slop in the the tow-ball hole and the heavy duty ball broke at the neck with the load weight and jurking shock action
I never use spring washers now
a thick flat washer if needed to take up space
but have had too many spring washer failures they don't seem to make spring washers out of quality steel anymore lok-tite is a better and safer option cheers
FollowupID: 794327

Follow Up By: Ross M - Monday, Jul 22, 2013 at 21:48

Monday, Jul 22, 2013 at 21:48
Yes, I see that, he posted that after I replied.

The neck of the ball is just under the head, part of the ball lead in curve and not the shank as I see it. Neck is above the flange, shank is below the flange.

If above the flange is where it failed and as the ball develops, then I would be looking at the surface finish ie, machining quality. Possibly a sharp groove which begins to fail and looks smooth in the fracture.

Something which fails quickly with force usually has a grainy, ripped apart surface.
FollowupID: 794379

Reply By: Motherhen - Sunday, Jul 21, 2013 at 19:52

Sunday, Jul 21, 2013 at 19:52
As farmers, tow ball breakages are not uncommon. This is why you have safety chains. As said, be sure the towball is rated to take your caravan weight, and replacing every few years is cheap insurance.


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AnswerID: 515146

Reply By: Member - Andrew - Sunday, Jul 21, 2013 at 21:54

Sunday, Jul 21, 2013 at 21:54
Hi net J

It would be very interesting if you could identify the make and perhaps post a picture of the failure.
it may also be of interest to your local registration authority in case it is a substandard product and not actually made to the standards.
There is always an issue with what are effectively "counterfeit" parts displacing the slightly more expensive but complying parts. This has happened with suspension and driveline components as well as mag wheels.
The supplier should be able to advise where it came from so it's legitimacy can be verified.

If it turns out to be legitimate it would be good to get some feedback on the actual cause of the failure, ie manufacturing fault, fatigue, overload or shock loading due to looseness.
AnswerID: 515150

Follow Up By: net J - Tuesday, Jul 23, 2013 at 09:10

Tuesday, Jul 23, 2013 at 09:10
Hi Andrew,
I am new to this forum and only wanted feed back on the broken tow ball. I don't know how to send a photo but I have two. The local Dealer supplied the towing kit and installed it so I trust it is first class and maybe just a metal fault??
I will update the post when I find out more information.
Thanks for you comments.
FollowupID: 794398

Reply By: Lyn W3 - Sunday, Jul 21, 2013 at 22:41

Sunday, Jul 21, 2013 at 22:41
Think I'll stick to the tongue and ball I got from the USA.

Both rated at 12,000lbs with the ball having an 1 1/4" shank.
AnswerID: 515152

Follow Up By: harry & the hobbit - Monday, Jul 22, 2013 at 08:21

Monday, Jul 22, 2013 at 08:21
Why is it so difficult to get a higher rated ball in Australia? A quick search only brings up those rated to 3500lbs.
FollowupID: 794306

Follow Up By: Lyn W3 - Monday, Jul 22, 2013 at 11:42

Monday, Jul 22, 2013 at 11:42
In the USA they tow much heavier loads compared to here, therefore there is a need for higher rated equipment. In Oz the basic limit is 3500kg so why exceed this rating.

A lot of the tow balls here have just a 7/8" shank whereas in the USA most are 1" or 1 1/4" shanks.
FollowupID: 794319

Follow Up By: garrycol - Monday, Jul 22, 2013 at 12:04

Monday, Jul 22, 2013 at 12:04
Harry & Hobbit

Supercheap sell 3500kg rated balls - so not hard to find.
FollowupID: 794322

Follow Up By: Lyn W3 - Monday, Jul 22, 2013 at 12:21

Monday, Jul 22, 2013 at 12:21

Think he made a mistake saying 3500lbs instead of 3500kg. In the USA you can get a 50mm/2" ball rated to 15,000lbs or about 7,000kg. which are machined from a solid billet.
FollowupID: 794325

Reply By: Thinkin - Monday, Jul 22, 2013 at 10:15

Monday, Jul 22, 2013 at 10:15
Hi net j, think back if you might have gone down a sharp gully or gone over a sharp hump
where you might have articulated the ball coupling over its limit. This manoeuvre could stress and fracture the ball where it could break at some later stage .
If this is the case you might not have any concerns.
AnswerID: 515161

Follow Up By: Thinkin - Monday, Jul 22, 2013 at 10:26

Monday, Jul 22, 2013 at 10:26
I should have added a treg type hitch might suit your purpose
FollowupID: 794312

Follow Up By: net J - Tuesday, Jul 23, 2013 at 08:57

Tuesday, Jul 23, 2013 at 08:57
The caravan is a Jayco Heritage and we tow with a Hayman Reece towing pack. The van has not been off road. I must admit Mt Lindsay has steep areas and sharp bends but it is a main road. We don't know what caused it and that is why I have created this post. From the post I have seen I am thinking it was a "Stress Fracture or a Faulty tow ball".
Thanks for your input.
FollowupID: 794395

Follow Up By: Lyn W3 - Tuesday, Jul 23, 2013 at 09:05

Tuesday, Jul 23, 2013 at 09:05
You need to tell us what the broken ball was rated at. If it was only rated at 2000kg and you are using a WDH well there's your problem.
FollowupID: 794397

Reply By: Michael ( Moss Vale NSW) - Monday, Jul 22, 2013 at 18:55

Monday, Jul 22, 2013 at 18:55
A ball for towing is a pretty outdated bit of engineering! A Treg or Trigg hitch,is in my opinion is a better option. It provides better articulation, some of the shock to be absorbed through the polyurethane block and the securing pin is secured from both ends. If its a cheap imported ball, you wouldn't know where it was made or the steel it was made from. Its rare to see a brand name stamped on a towball, so there is never anyone to blame in case of a failure. Michael
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AnswerID: 515187

Reply By: The Bantam - Tuesday, Jul 23, 2013 at 10:47

Tuesday, Jul 23, 2013 at 10:47
It must be understood that the common or garden tow ball ( no matter how good) is a fundamentally flawed device.

It must also be understood that, there is not a large safety margin in any light trailer towing parts, well certainly not compared to regulated lifting tackle or heavy transport items.

Tow balls do break and the place they are known to break is directly under the flange.....any engineering student that was listening in class will tell you why.

That is where there is a sudden transition from a narrow shank to the larger part of the ball.

Good towballs should have a small radius at this point, but it still remains the single biggest stress point on the ball.

This is why we DO NOT use tow balls for snatch recoveries.....they can break, they are known to break and they DO break.

This is compounded by the generally rough and buthcerous level of enginering in ALL light trailers and caravans ....AND...the ever pressing desire for people to push their towing capacities to the very limit of the allowed capacity.

If you have a large trailer or van, it is wise to.

Be very fussy about the brand of ball you buy

Replace said ball regularly

carry a spare ball


Make sure your safety chains can do exactly what they are suposed to do, and that includes maintain controll of the trailer and not allow the drawbar to strike the ground under any circumstances.

It has also been postulated by some that there are inherant weaknesses built into the ball and coupling so that if the trailer flips, it will break away and have far less tendancy to take the tow vehicle with it.

So the tow ball is fundametaly flawed and known to beak....this is before we consider cheap nasty items and out of specification stresses like over articulating the a hitch that has definite limits.

AnswerID: 515233

Follow Up By: The Bantam - Thursday, Jul 25, 2013 at 09:35

Thursday, Jul 25, 2013 at 09:35
Just a little follow up on some very real issues that many people will not be aware of.

First we must understand that there is more to the ADR requirements and the various regulations than a lot of people wish to understand.

Overseas towing practice and the hardware they use, may to some, make our regulations seem inadequate or out dated.....but overseas...especially the US..they have different considerations and a completely different package of regulations.
BTW they seem happy kill a lot more people on their roads than we do in proportion.


The standard ADR compliant 50mm tow ball is rated at 3.5 tonnes towed capacity...lets not bother with the fine detail beyond that..except to say that there is not a huge safety margin like there is in lifting gear.

The standard ball has a 7/8" UNF shank....that fits all standard tow bars as factory drilled.

There are variations available, but in Australia, towing a light trailer on a draw bar, rear hitched with a ball is limited to 3.5 tonnes.

If the ball is rated at 3.5 tonnes it will be stamped on the top.

NOW...there are balls available that are only rated at 2.5 tonnes (and less), (not sure about their ADR compliance), but either way they would be adequate for those towing a 750Kg box trailer, but a disaster waiting to happen for anybody doing heavy towing.

Even though my vehicles will not tow 3.5 tonnes, I would not buy or leave fitted a ball rated any less than 3.5 tonnes......its just not worth the $5 saved.

there are also specialty balls available, such as high rise balls, that raise the ball on the towbar around an inch......none of these I have seen are 3.5 tonne rated.

There are 50mm, 3.5 tonne rated balls available with 1 inch shanks, that may address the findamental weakness to a point.
But it requires the tow bar to be drilled out and then a standard ball can not be fitted to that tow bar.

There is a 70mm 4.5 tonne rated tow ball and coupling available in this country BUT neither are ADR approved and thus illegal for use on the road.

The only other ADR approved ball and coupling available is the 9 tonne 3 inch format intended for goosekneck trailers.

Even the use of poly block couplings like the Trigg would be limited to 3.5 tonnes by the standards, but in reality are limited to 3 tonnes.

All heavier draw bar towing goes across to Pintle hook & eye, and lots of industrial users go across to pintle hook at 2 tonnes, mostly because anything that heavy they expect to tow with a truck.

We keep comming back to pushing the limits of the of the format.....AND...realy pushing the limits of safety.

When all states require a truck licence to drive a rigid vehicle over 4.5 tonnes, I remain gob smacked that we allow people to drive combination well above that limit , towed by a passenger car that is not specifically designed for the purpose and in a form that would be considered fundamentally unstable in heavy transport.

FollowupID: 794599

Follow Up By: Lyn W3 - Thursday, Jul 25, 2013 at 12:04

Thursday, Jul 25, 2013 at 12:04

"There is a 70mm 4.5 tonne rated tow ball and coupling available in this country BUT neither are ADR approved and thus illegal for use on the road."

That statement is a load of BS, we just had a 4.5T equipment trailer delivered with a 4.5t 70mm ball and coupling all fully ADR compliant and registered complete with stamped CRN numbers.

FollowupID: 794604

Follow Up By: garrycol - Thursday, Jul 25, 2013 at 13:25

Thursday, Jul 25, 2013 at 13:25
Well it is not BS and is a bit harsh - maybe not correct but not BS. BS implies deliberate misleading information where I am sure Bantam posted up in good faith.

Most larger jap style forward control small trucks that are used by used by service utilities like Telstra and power companies use a combined ball/pintle hook to tow and the balls used on these are the 70mm version and are all legal.

But doesn't seem relevant to to overall discussion - given the OP has only just got the vehicle and the tow package as part of the purchase this would indicate to me the ball would have been an approved 3500kg tow ball (other than Ebay or overseas can you buy a non rated tow ball in Aust??).

The fact it has failed is a major concern as high lighted in the thread.

FollowupID: 794605

Follow Up By: The Bantam - Thursday, Jul 25, 2013 at 21:31

Thursday, Jul 25, 2013 at 21:31
There may be any number of non-standard couplings like the Trigg off road coupling that are individually complinaced as a matched pair.

To be compliant the coupling must be used with the hitch specificaly designed for it.

BUT the only generic ball coupling (a coupling that is interchangable between brands) mentioned in the ADRs is the 50mm ball, with a limitation of 3.5 tonnes.

Yes there are combined pintle hook and ball couplings out there.
The only ones I have seen that are expressly ADR approved use a 50mm ball.
These are common on telstra, council and power utility company vehicles.
Because they allow the vehicle to tow trailers fitted with both the generic 50mm coupling and the generic 75mm pintle ring.

Interesting that when used as a pintle hook they are rated at 6 tonnes, but when used as a 50mm ball they are only rated at 3.5 tonnes.
The ball functions as the hook when functioning as a pintle.

Like may things too......the mentioned 70mm ball may be rated at 4.5 I'd want to see the approval paperwork for both the ball and the coupling before I towed it on the road.

FollowupID: 794634

Follow Up By: Lyn W3 - Thursday, Jul 25, 2013 at 23:30

Thursday, Jul 25, 2013 at 23:30
Here you go Bantam:

ADR Approved 4.5T coupling

ADR approved 70mm balls also available there.
FollowupID: 794637

Follow Up By: The Bantam - Friday, Jul 26, 2013 at 09:09

Friday, Jul 26, 2013 at 09:09
As I said.

4.5 tonne Electric Coupling to suit 70mm Tow Ball.

Park Brake included. ADR Approved. CRN 45126

If your 4.5t electric coupling has no CRN (Commonwealth Registration Number) then it can only be used for agricultural purposes. There is no legal approval for a tow ball over 3.5t to be used on the road without a CRN.

If the CRN cannot be found on your Invoice or ask your supplier for it. If he cannot give it to you, ask for a credit on the one you have purchased.

4500kg x 70mm Tow Ball - 1 1/4 inch shank not included.

CM235 4.5t Coupling Installation Instructions.

Install coupling over tow ball and adjust side nut until tight then back off 1/2 turn.

Use 4 x 5/8" Grade 12 bolts of suitable length + Washers + Nylocks.

Max Torque 100 ft/lbs

Also note the comments that come at the head of the page linked.

Australia Standards have their origins in Germany and are tied to the EU standard that are quite rigorous.

SAE is the Standard American Equivalent and is less rigorous than the Australian Design Rules.

Pintle Hooks rated over 3.5t when used on the road must comply with the Australian Design Rules and be ADR Approved.

Pintle Hooks when use on the farm and NOT on the road or highway can be SAE or NO standard. These Pintle hooks are usually cheaper.

SAE Pintle Hooks are illegal for Use on Australia roads and Highways.

Generally, when buying Pintle Hooks or any towing towing equipment over 3.5t ask for the CRN number or the test report number. © Steve Wotherspoon

also note that on th linked page there are several examples of 50mm ball/ pintle hook combinations.

To put it bluntly....if you are towng anything over 3.5 tonnes you should be doing so with a truck and realy you should be coupling with either a pintle hook or a turntable.

There are several couplings that while individually approved are non standard and are in general used to push the limits of the regulations.

Remember as soon as you go over 4.5 tonnes you are in the relms of heavy transport and building a trailer becomes very much more strictly regulated.

FollowupID: 794648

Follow Up By: garrycol - Friday, Jul 26, 2013 at 14:01

Friday, Jul 26, 2013 at 14:01
So if you have a 70mm tow ball that is CRN = 45125 approved it is ADR approved and these are available at on the above mentioned site.

So ADR approved 70mm 4500kg balls and other towing equipment is available.
FollowupID: 794670

Follow Up By: Rockape - Friday, Jul 26, 2013 at 17:17

Friday, Jul 26, 2013 at 17:17
instead of a book written about the world and any other big place.

YES. Lol. I think someone should be in politics.
FollowupID: 794678

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