Al-Ko Trailer Tongue failure

On Friday, July 8, 2016 at 1:08:38 PM UTC-7, wrote:
Rather than drifting this thread on into principles of bolt engineering, instead lets focus the on the real problem. The new Al-Ko tongue design again leads to concerns of possible tongue failure. The old style Cobra round tongue also has a history of failures and also generated the same concerns. As Cobra trailer owners, we should be campaigning Spindelberger to provide better engineered tongue components. A new, well optioned, Cobra trailer can easily cost $20,000 or more. The last thing I expect to do after taking delivery of a new trailer is upgrading tongue bolts.

On Thursday, July 7, 2016 at 5:21:21 PM UTC-4, Dave Springford wrote:
On my way home from Nephi (towing my trailer with the RV) I stopped for fuel and found one of the bolts that holds the Al-Ko trailer tongue together was gone as can be seen in the picture he


No intention to get off into the weeds on bolting technology, but there's no evidence at this point indicating a bolt shear failure rather than the bolt working its way out. Dave would have likely found the remainder of the bolt shank in the square section draw bar if the bolt failed in shear. If there was nothing remaining then the probable scenario is the nut coming loose and the bolt working its way out. Dave will have to let us know what the situation really was. If the nut came loose then loctite is a better solution than nylocks and there's no need to upgrade the bolts on your new trailer.

On Friday, July 8, 2016 at 2:13:45 PM UTC-7, Casey wrote:
On Friday, July 8, 2016 at 4:08:38 PM UTC-4, wrote:
Rather than drifting this thread on into principles of bolt engineering, instead lets focus the on the real problem. The new Al-Ko tongue design again leads to concerns of possible tongue failure. The old style Cobra round tongue also has a history of failures and also generated the same concerns. As Cobra trailer owners, we should be campaigning Spindelberger to provide better engineered tongue components. A new, well optioned, Cobra trailer can easily cost $20,000 or more. The last thing I expect to do after taking delivery of a new trailer is upgrading tongue bolts.

Right On. I can't believe they are still using steel wheels with hub caps. Nice aluminum rims are not even an option. Not sure if current hubs come with bearing buddy/quick lube fittings. But if not that is amazing as well. A shot of synthetic grease every couple of years and one would never need to replace bearings or have to open bearing cap.

Has anyone checked if their fuel tank is within the range of motion the chains will allow?

To get an idea of what the trailer tongue has to deal with behind an RV, try riding in the back seat of one of those shuttle buses built on a truck chassis, AKA "short bus". Enjoy a glass of something colorful if you dare. After that, the idea of loosening or breaking things shouldn't come as a big surprise.

Casey, you've probably noticed when replacing the steel wheels on your own trailer that AlKo have used sealed bearings for more than a decade.

Jim

Keep in mind (not really directed to Herb....) if you upgrade the bolt rating, it ALSO requires a higher torque value to maintain the correct clamping force within the elastic limits of the fastener.
Common issue is, "well hey, I put in better hardware, but it still failed!!", person never properly torqued the better hardware to an appropriate torque valve within elastic range.
I'll stay out of lubed vs. dry threads, rusty vs. clean threads........

Just checked my trailer year 2011 and the same cross bolt was sheared at the nut. The bolt was still in but the nut was gone and you could see the shear plane. and yes the trailer is towed with a motor home.

David
ASG29E BV

wrote on 7/8/2016 7:20 PM:
Just checked my trailer year 2011 and the same cross bolt was sheared
at the nut. The bolt was still in but the nut was gone and you could
see the shear plane. and yes the trailer is towed with a motor
home.

Were there any threads on the bolt in the sheared area?

--
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email me)
- "A Guide to Self-Launching Sailplane Operation"

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On Friday, July 8, 2016 at 6:14:51 PM UTC-4, JS wrote:
On Friday, July 8, 2016 at 2:13:45 PM UTC-7, Casey wrote:
On Friday, July 8, 2016 at 4:08:38 PM UTC-4, wrote:
Rather than drifting this thread on into principles of bolt engineering, instead lets focus the on the real problem. The new Al-Ko tongue design again leads to concerns of possible tongue failure. The old style Cobra round tongue also has a history of failures and also generated the same concerns. As Cobra trailer owners, we should be campaigning Spindelberger to provide better engineered tongue components. A new, well optioned, Cobra trailer can easily cost $20,000 or more. The last thing I expect to do after taking delivery of a new trailer is upgrading tongue bolts.

Right On. I can't believe they are still using steel wheels with hub caps. Nice aluminum rims are not even an option. Not sure if current hubs come with bearing buddy/quick lube fittings. But if not that is amazing as well. A shot of synthetic grease every couple of years and one would never need to replace bearings or have to open bearing cap.

Has anyone checked if their fuel tank is within the range of motion the chains will allow?

To get an idea of what the trailer tongue has to deal with behind an RV, try riding in the back seat of one of those shuttle buses built on a truck chassis, AKA "short bus". Enjoy a glass of something colorful if you dare. After that, the idea of loosening or breaking things shouldn't come as a big surprise.

Casey, you've probably noticed when replacing the steel wheels on your own trailer that AlKo have used sealed bearings for more than a decade.

Jim

Jim,
Wow. I did not realize that. My trailer is a 1975 Pfeiffer but probably does have the Alko axle. The bearings are not sealed of course. I pulled the bearings out, inspected, cleaned and re-greased with synthetic grease. I'm so use to re-greasing trailer bearings that I did not even know/realize that they were using sealed bearings. I never had a trailer with sealed bearings. I guess not common in the US. I just wonder why they are still using steel wheels and hub caps without a upgrade to aluminum wheels.

Casey

In answer to the question if the bolt was sheared in the thread plane. Yes.. It looks to me like the threads were crushed in the original shear plane with the bolt tight and that allowed the nut to come loose and back off a bit. The actual shear was about 1/2" from the end of the bolt. There is about 3/4" of thread remaining. Ideally the shear plane should not have threads.

David
ASG29E BV

Here's a better picture of the bolt I added to the tongue of the Duo trailer to eliminate the shear loads on the two cross bolts.

http://www.foxonecorp.com/images/tongue%20bolt.jpg

KS

On the subject of trailer tongue issues, I just noticed that the coupler can rotate 360 degrees inside the tongue round tube in my Cobra trailer. It was always relatively loose and could rotate 30 degrees but not 360. Not sure when it happened but it towed just fine before I noticed this today. Nothing looks broken and all bolts seem to be in place. Problem is that I am in the middle of a flying trip. Anyone experienced this or has an idea what is going on and how to fix this? And most importantly, is the trailer still road worthy?

Thanks

Ramy

Got a very quick reply from Alfred that my issue is simple to fix and not a big concern so I am relieved. Excellent customer service.

Ramy