Loose wheels and ATC

[retired ian]

I've only been towing for 3 years, so if this has been discussed before I'm sorry.
I had a wheel detached and strike a car recently.

I had caravan stored at home on axle stands.
The wheels were free running.
I checked the 130nm wheel bolts as soon as it was on the ground.
On the day of travel I hitched up and did the usual lights, jockey wheel,hitch AND checked the wheel torque again.

We set off and I noticed a slight tugging whilst towing. I thought it was the wind or bad road surfaces. Nevertheless we stopped at the first layby 5 miles from home and did a visual and checked nothing was loose.
Satisfied we resumed our journey. Still feeling a tugging sensation we decided to stop again at the next layby.
We didn't make it, it was only 15 miles from home.
A wheel detached and struck a car, no injuries, luckily.
On inspection the brakes were toasty , really hot.
Whilst waiting for recovery, a couple of people stopped. They said "that's happened to me!"
In the end my wife went home to get my trolley jack, and a helpful neighbour for backup.
We managed to get it up , quite difficult when it's sitting on the motor mover axle.

Are you still awake!!!

I'm surprised at the blasé attitude of the caravan industry.
We went to the local caravan centre.
The fitter came out and we told our story.
"I bet it's the nearside wheel" he said.
Right first time, I replied.
"We've had a few of these"
He explained about how to fit wheel correctly.
I asked what were causes? " Can't always tell, it just happens sometimes"
What about heat? " That can be a cause".
So I thought back to the tugging feeling and the heat in the brakes.
On further investigation it appears, if you have an intermittent 12v supply "the ATC can go through it's check cycle whilst on the move.
Heated brakes explained......maybe!
I noticed a poorly fitting 12v 20 amp supply fuse.
This supplies the ATC . Also a not quite closed junction block under caravan.
Who knows?
We're booked in for an expensive brake drum and shoes, a wheel box wheel spat, possibly a wheel etc.

Well done if you read up to here!!

Questions for the caravan community.
1 why do you accept poorly designed overpriced parts?
2 why does no one investigate these issues?

The wheel issue could be partially solved by a spigot for locating the wheel. If the bolts slacken the wheel should hold on.
Penny pinching car manufacturers choose safety over cost. Caravan industry choose fat margins over safety.
At present nearside bolts only have to slacken slightly, the wheel is then eccentric the bolts then rapidly part company, and the wheel then looks for a victim.
Offside wheels don't suffer as much from this problem, as it's trying to tighten the wheel bolts.

A simple positive locking device for the wheel bolts.

An ATC button.
Connecting the 13 pin would enable the ATC.
The button or key switch would be used solely for a test cycle and show green led if it's OK.
On the move the ATC would not recycle with intermittent voltage.
The other advantage would be no led showing if a fault was detected on the journey.
But the ATC would still be active and would encourage investigation if no led was showing.

Phew! Thanks for reading.
That's another 10 Minutes of your life you won't get back!

 

[Hutch]

Some time ago, 10 to 12 years ago Bailey recalled their caravans for wheels coming loose, this was to do with the type of bolts being used.

There has been much debate about the direction of rotation and wheel bolts coming loose but again nothing proven.
Glad you didn't have a physical accident to yourself or others.

 

[otherclive]

After their spate of problems Bailey introduced the WSL bolt which then was marketed for other caravans. Although at the time other makes did not seem to be having wheel problems, so perhaps Baileys wheels may have contributed to the problem.

But by checking torque before setting off you did the right thing, and your wheel detached at a distance less than normally recommended for a second check if wheels have been removed and refitted. Your comments wrt ATC do seem to have some validity, but I’ve never heard them before.
Hope you get it sorted.

If you search on the Forum for WSL you get lots of hits.

 

[IanB1485]

Thanks for the heads up and no it wasn't boring or overly long winded as it conveyed important information based on personal experience and an odd issue with a faulty ATC system and a reminder to all to physically check the wheel nuts for tightness with a wrench , not just visual. and the centre of the alloy rim for a temperature rise. It also highlights a possible failure mechanism of alloy wheels on Alko trailers , extreme heat causes the bolts to come loose( rim softening ?). . On Australian caravans I saw a video where the brake control was a dial and warning button in the cab of the car, the rig had crashed despite the brake control See

View: https://youtu.be/xD735nwYDQk
. You can also get wheel bolt position indicators like they have on HGV vehicles.

 

[Lutz]

I am convinced that the issue affecting Bailey caravans is due to them not coordinating adequately with AlKo engineers in the selection of their alloy wheels. After all, AlKo supplied the same chassis to other caravan manufacturers without a problem, so it must be a specific issue affecting only the alloy wheels that Bailey used.
It's difficult to comment on the ATC issue on the case in question without a thorough technical investigation and analysis.
The video above is not really very revealing. The electrical braking systems employed on Australian outfits do not meet European requirements, so it doesn't tell us very much.

 

[RogerL]

I am convinced that the issue affecting Bailey caravans is due to them not coordinating adequately with AlKo engineers on the selection of their alloy wheels. After all, AlKo supplied the same chassis to other caravan manufacturers without a problem, so it must be a specific issue affecting only the alloy wheels that Bailey used.
The video above is not really very revealing. The electrical braking systems employed on Australian outfits do not meet European requirements, so it doesn't tell us very much.

Aren't electric brakes now permitted in Europe - having previously been illegal for decades.

 

[Lutz]

Aren't electric brakes now permitted in Europe - having previously been illegal for decades.

They are legal, but they must not involve any manual intervention as in the case of Australian (and American) electric brakes, and they must be type approved.

 

[JTQ]

The ATC's pre use safety test, going through a full cycle, IMO can't reasonably be criticised because it also means it throws up defective powering issues. Very much to the contrary, it makes that powering defect very evident, and of course without powering the ATC is useless.

Here the action is to either sort the powering defect, or temporarily for that trip disable it, so it can't intermittently power the ATC.

I would like to have an ATC system that proves to me it is working before I leave, rather than face the possible outcome during a trip, it was not.

 

[JTQ]

Spigot fitted wheels, as viable in "user changeable" vehicle road wheels, does nearly zero in retaining the wheels. To be "user changeable" the spigot system has to be a clearance fit, so as a consequence a loose wheel would shuffle on the spigot.
Our wheels, cars and caravans are in respect to radial loading, solely held on by friction, this generated by the level of tension in the bolts or studs clamping, the wheels to the hub.
Once that required level of tension is lost, most typically because of settlement or "give" , the wheel starts moving as the radial load rotates round. That movement then results in the bolts/nuts turning and or the components smashing each other up . Consequently the wheel very soon comes free spigot or not. No bolts, smashed or lost, then no retention. Bolts don't turn until there is already an issue.

Key here in retaining the wheels is the tension retained in the bolts, it must be adequate so the wheel can't move, move and failure follows, often very quickly.

The mentioned WSL bolts use the centuries old engineering principle that the longer the worked length of the bolt, the more tolerant is the tension level retained, for any given settlement or give in the clamping system.
WSL bolts offer about three times the ability to retain an adequate tension level for a given amount of settlement, that the basic bolts had, even at like for like torque ups.

 

[retired ian]

The ATC's pre use safety test, going through a full cycle, IMO can't reasonably be criticised because it also means it throws up defective powering issues. Very much to the contrary, it makes that powering defect very evident, and of course without powering the ATC is useless.

Here the action is to either sort the powering defect, or temporarily for that trip disable it, so it can't intermittently power the ATC.

I would like to have an ATC system that proves to me it is working before I leave, rather than face the possible outcome during a trip, it was not.

I found it hard to describe the test button proposed for the ATC.
The way I was thinking was.
1 Connect 13 pin plug, this applies power to ATC.
2 press test button and make ATC cycle as normal.
Green LED all ok.
3 should the power be interrupted during travel the ATC would still be powered after it re- connected .
The only difference would be a blank LED at end of journey or coffee stop.
Still powered and no worse than present setup.
Blank LED would indicate there had been a fault.
The way the ATC works now. The LED would show green and pretend it's all been fine.
( Nothing to see here! I'm green so I've been ok all the way).
Finding an intermittent fault is your worst nightmare.
If your driving it's difficult to see the LED.
Bad road surfaces can give the same impression as brakes.
This wheel detached in the space of 15 miles.
I stopped after 5 miles and intended to stop at the next layby total 16 miles. I only made 15 of those miles!
Mine test cycles, and turns green.
I attached a video camera under the caravan,
( focused on the balance stirrup ) and did a short test run. Every thing looked ok.
I could be making the facts fit my thoughts.
But this was after I had tightened up the 12v 20a fuse and charged the car battery.
Smart alternators seem to keep car batteries at a low charge
I bought a cheap plug in volt meter, you'd be surprised at the way the alternator charges.
1 I intend to fit infrared sensors to the brakes.
2 I will fit a backup camera focused on the nearside wheel.
3 I'm in the process of designing and making a positive wheel nut locking device. ( In metal as 3d printing in plastic is inviting it to melt if the brakes get hot).
4 nut indicators give the user false security. At least they are brightly coloured when pick them up with your detached wheel.
Maybe it's over the top but I don't want a repeat of this event.

 

[retired ian]

Spigot fitted wheels, as viable in "user changeable" vehicle road wheels, does nearly zero in retaining the wheels. To be "user changeable" the spigot system has to be a clearance fit, so as a consequence a loose wheel would shuffle on the spigot.
Our wheels, cars and caravans are in respect to radial loading, solely held on by friction, this generated by the level of tension in the bolts or studs clamping, the wheels to the hub.
Once that required level of tension is lost, most typically because of settlement or "give" , the wheel starts moving as the radial load rotates round. That movement then results in the bolts/nuts turning and or the components smashing each other up . Consequently the wheel very soon comes free spigot or not. No bolts, smashed or lost, then no retention. Bolts don't turn until there is already an issue.

Key here in retaining the wheels is the tension retained in the bolts, it must be adequate so the wheel can't move, move and failure follows, often very quickly.

The mentioned WSL bolts use the centuries old engineering principle that the longer the worked length of the bolt, the more tolerant is the tension level retained, for any given settlement or give in the clamping system.
WSL bolts offer about three times the ability to retain an adequate tension level for a given amount of settlement, that the basic bolts had, even at like for like torque ups.

A cars front wheels have driven,stop and turn.
A caravan only brake.
I agree bolts don't turn until there's an issue.
Fail safe is a good motto.

 

[JTQ]

I would suggest that positively locking the bolts from turning will only delay an outcome till they are smashed up.
Wheels coming loose can readily happen before they had start to even try and turn. Them turning is a consequence of being loose, not the cause of coming loose.

IMO if you can't trust the integrity of the ATC powering set up, would it not be cheapest and more effective to have an electric warning of lost of ATC power; a drop out relay sounding a klaxon powered by the van's battery?

The ATC by design test cycles if powering is lost, on being re-established.
So unless you alter this aspect of the ATC it will cycle on re powering following an intermittent lose of power.
What the LEDs indicate is a side issue.

IMO it would be quite wrong to fundamentally alter the ATC's proven operating system, just to over come having dicky powering; sort the powering issue not the ATC. I suspect if any insurer is involved a DIY disabling mod to the ATC would be grabbed at with some enthusiasm.

 

[retired ian]

Not sure about the locking device.
But the aircraft industry use positive locking and it tends to work.
Your other point about power supply is valid.
I'm going to set up a voltmeter and variable resistor and power the ATC with a battery. I'll then turn down the voltage and see where it drops out .
Then I'll connect a voltmeter to the car and see what's the lowest voltage coming from there.
It's possible the car is the fault.
I appreciate all the advice I'm getting. Hopefully when it's solved I'll share the knowledge we've gained.

 

[JTQ]

But the aircraft industry use positive locking and it tends to work.

But do they for anything like a similar bolting system, one designed to frictionally carry a radial rolling load? Indeed bolt locking is well practiced but is only relevant where the application benefits from it.
You also wire lock them for example where a free loose bolt can itself be a hazard.

Here as explained, all you will achieve is a short delay whilst the forces get to work smashing up the bolts, and here they are in the scale of things quite puny and not applied as "fitted shear bolts", just tension loading bolts.
As said earlier our wheels are held in radial loading by friction, not by shear.

IMO, you are way better going the WSL route; they IMO know the problem and the solution, not that it is novel or new. A technique I have used myself to cure a client's bolting system failures, one very like this. I have zero connection with the WSL company, nor have I been a customer.

 

[retired ian]

But do they for anything like a similar bolting system, one designed to frictionally carry a radial rolling load? Indeed bolt locking is well practiced but is only relevant where the application benefits from it.
You also wire lock them for example where a free loose bolt can itself be a hazard.

Here as explained, all you will achieve is a short delay whilst the forces get to work smashing up the bolts, and here they are in the scale of things quite puny and not applied as "fitted shear bolts", just tension loading bolts.
As said earlier our wheels are held in radial loading by friction, not by shear.

IMO, you are way better going the WSL route; they IMO know the problem and the solution, not that it is novel or new. A technique I have used myself to cure a client's bolting system failures, one very like this. I have zero connection with the WSL company, nor have I been a customer.

Just for information the wheel bolts are 10.9

Grade 10.9 bolts have a minimum tensile strength of 1040 MPa (145,000 psi).

Here's a more detailed breakdown:

• What is a Grade 10.9 bolt?
  These bolts are known for their high strength and are often used in applications requiring high clamping forces or where safety is critical.
  
  
• Material:
  They are typically made from alloy steel that has been quenched and tempered.
  
  
• • Other Properties:
    • • Yield Strength: They have a minimum yield strength of 940 MPa.
        
      • Hardness: They typically have a hardness range of 32-39 HRC.
        
      • Elongation: They have a minimum elongation of 9%.