Rim separates from flange

[geoffleach]

The tractor in question is an Antonio Carraro TRH 9800 with 350 hours.

At 150 hours, the left rear wheel rim (and tire) separated from the flange. The flange was securely attached to the axle. The bolts that held the rim and flange together were secure, but bolt holes on the "ears" on the flange had been torn out. Factory replaced the flange and rim under warranty.

An 200 hours the problem repeats. I've caught it when the bolt holes are only slightly elongated. The nuts are still securely fastened to the bolts.

There are no problems with the other wheels.

As this is the second time in exactly the same way, I'm inclined to think that I should be looking elsewhere for the source of the problem. Any suggestions? (The factory is on vacation!)

 

[Sysop]

If it is elongating the holes, it is not "secure" enough and moving during operation and wearing the holes out. I think most tractors call for about 500lbs/ft of torque on those fasteners.

 

[Spanner]

The implication made is that you may want to look at the terrain and the way you're operating it. Also the load?

Is there any position you get into where you think you could be overloading on that corner of the machine?

If you aren't in the habit of altering your wheel track (width) perhaps you could have the rim welded to the centre flange with reinforcements?

 

[geoffleach]

The implication made is that you may want to look at the terrain and the way you're operating it. Also the load?

Is there any position you get into where you think you could be overloading on that corner of the machine?

Terrain in hilly and rough. However the operation would not seem to favor one wheel.

If you aren't in the habit of altering your wheel track (width) perhaps you could have the rim welded to the centre flange with reinforcements?

An excellent idea. Thanks.

 

[geoffleach]

If it is elongating the holes, it is not "secure" enough and moving during operation and wearing the holes out. I think most tractors call for about 500lbs/ft of torque on those fasteners.

AFAIK the fasteners are secure. In any case, even if I was to blame, the first occurrence was with the factory-installed wheels. And when I took that rim apart, I had to put a 4-foot extension on the breaker bar to get the nut off of the bolt.

 

[Sysop]

AFAIK the fasteners are secure. In any case, even if I was to blame, the first occurrence was with the factory-installed wheels. And when I took that rim apart, I had to put a 4-foot extension on the breaker bar to get the nut off of the bolt.

That's about right. Perhaps step up to a 5 or 6' extension for reassembly. Welding as advised above is an excellent idea.

 

[Dave M7040]

The tractor in question is an Antonio Carraro TRH 9800 with 350 hours.

At 150 hours, the left rear wheel rim (and tire) separated from the flange. The flange was securely attached to the axle. The bolts that held the rim and flange together were secure, but bolt holes on the "ears" on the flange had been torn out. Factory replaced the flange and rim under warranty.

An 200 hours the problem repeats. I've caught it when the bolt holes are only slightly elongated. The nuts are still securely fastened to the bolts.

There are no problems with the other wheels.

As this is the second time in exactly the same way, I'm inclined to think that I should be looking elsewhere for the source of the problem. Any suggestions? (The factory is on vacation!)

This advice applies to a personal car as much as it does larger machinery.

Once a wheel fastener has come loose, no amount of re-tightening will keep it secure.

The fit and alignment of the various parts becomes compromised in minute amounts by the relative movement of the parts and sufficient to compromise the securement of the wheel and tire. It is not just the clamping action from tightening that holds things in place but the centering action of the various fasteners.

Since it has happened twice on the same wheel and not on any others, I would be looking for a new hub and wheel studs which may include the axle shaft itself plus all new wheel and rim hardware.

At such low hours, starting to re-engineer the wheel assembly by welding seems inappropriate and you are taking on responsibility that belongs to the manufacturer. Imagine driving along a road with a heavy implement and the same rear wheel assembly fails and you swerve into oncoming traffic. People are badly injured or dead and there is the welding having failed........ deep crap to say the least.

You have an expensive sophisticated machine and the manufacturer needs to be held responsible.

Dave M7040

 

[Spanner]

I don't read it as the hub bolts that have failed Dave.
Correct me if I'm wrong -
but I read it that the rim bolts have let go.

???

 

[Egon]

Bolts that have been over stressed past the yield point. They need to be replaced.

 

[CincyFlyer]

That's about right. Perhaps step up to a 5 or 6' extension for reassembly. Welding as advised above is an excellent idea.

Perhaps a proper torque wrench for reassembly, rather than guesstimating.

 

[boomer1025]

Try putting rubber gasket material between the hub and rim where they bolt together. Also make sure the nuts are not bottoming on the bolts when you torque them.
For some reason your not getting enough clamping force or the surface between hub and rim is too slippy/smooth.
Another thing you might want to try is putting heavy flat washers under the bolt heads and nuts if possible.
Re-torque the bolts after several hours of use a couple of times

 

[CalG]

This can only be a hardware issue. Not sufficient clamping force to keep the clamped surfaces from moving.

Any movement is too much. The bolted connection will only continue to loosen. Suspect incorrect hardware. As mentioned, the nut may be bottoming on the threads before full clamping force is achieved. Rubber in the interface is a BAD IDEA. It only allows relative movement.

Welding would be an option to discovery.

My bet is a set of hardened washers and a close examination of just what is pinching up when you apply that five foot cheater will answer the question that even the dealer and mfg. warantee missed.

You didn't give the size of the wheel fasteners that are failing. If the bolt holes are torn, welding in some reinforcing tabs with new holes may be an expedient.

Post pics if you can. There may be evidence that has been missed. ;-)

As a stop gap, CHECK those wheel fasteners prior to every use. Any movement will show as "debris" at the faying surfaces. NO MOVEMENT IS ACCEPTABLE!

 

[geoffleach]

Here's the problem

The cap screw is M14x1.5x50mm, grade 8.8. That's 'as delivered' from the factory.

The first time this happened the rim-to-flange connections were ripped apart. This time I was alert to the problem and found it when the cap screws had worked a bit loose. The holes in the rim-to-flange connections appear to be unaffected.

I'm going ahead with new hardware and careful torquing, checking every use.

You suggest an 'hardened washer' What hardness spec would satisfy that?

Thanks for the help.

 

[geoffleach]

You have an expensive sophisticated machine and the manufacturer needs to be held responsible.

An excellent point, and one that I'll take to heart.

 

[CalG]

Commercially, "Hardened washers" are not often available in different grades as bolts may be.

Washers are either of high quality and "hardened", or they are not. and likely soft as butter!. Hardened washers are MARKED! So identification is easy.

Make sure there is sufficient clamping pressure with the bolted connection, and I feel your problems will be behind you. Check them often, they have shown a weakness.

Those fasteners are "hammered! No muy bueno!

The "problem" is obvious. The fasteners were not always tight.
Observe the damaged threaded region of the bolt. Positive indication that the clamping force had slackened, and the two surfaces worked against the the bolt . That should never happen in a wheel flange.