Broken Back Trailer

Today I drove past a weigh station with several police cars parked next to a dry van. The police had their emergency lights on, but there was no tractor in sight. The trailer had broken right in the middle, between the king pin and tandems. Bottom of trailer touching the ground and the roof had bent down in parallel. Sheet metal sides crumpled from the distortion. I couldn’t detect any sign of a rollover, just the broken frame and floor.

How does something like this happen?

Trailer Failure Cause - 2 examples

Our company has seen a few of these.

Many of the newer trailers do not have a full-length frame. They use a combination of the crossmembers and side walls to create the rigidity. When the rivets holding the sidewall to the rub-strip (inside) get broken away, the integrity of the trailer is compromised. Sometimes those rub strips get seriously damaged by forklift operators.

Sometimes Drivers wonder why we should even worry about the rivets on the sidewalls, but this is one example of what can go wrong if too many of those rivets are missing.

I hope this helps.

The majority of dry vans and reefers do not have an underframe per say, not like a flatbed or tank. The only true frame is that of the suspension/tandems.

Totally agree with the point about integrity and inspection details!

Much like a truss bridge, the van unit as a whole provides structural rigidity and integrity. The top cord and all of its connection points is highly critical. Exactly why any component damage like missing rivets, or damaged cross members can eventually cause a catastrophic failure. Always comes back to PTI. I see it skipped all the time…troubling.

Our company has seen a few of these.

Many of the newer trailers do not have a full-length frame. They use a combination of the crossmembers and side walls to create the rigidity. When the rivets holding the sidewall to the rub-strip (inside) get broken away, the integrity of the trailer is compromised. Sometimes those rub strips get seriously damaged by forklift operators.

Sometimes Drivers wonder why we should even worry about the rivets on the sidewalls, but this is one example of what can go wrong if too many of those rivets are missing.

I hope this helps.

I deliver a lot of aluminum extrusions to the trailer manufacturing plants. It is unnerving to see how flimsy a dry-van trailer is before the top rail and sidewalls are put in place. G-Town referred to it as the top cord, but we are talking about the same piece. That piece is really the main gusset supporting the weight of your freight. The dry-van trailer is built on the same theory as a suspension bridge. The sidewalls are like the cables and the top rail is the supporting member.

That was a simplified explanation. The engineering is a little more complex, but I like to keep things simple so we can more easily understand them. The sidewalls are doing more than cables on a suspension bridge, but it's a very similar structural solution.

Very interesting and educational.

I assume reefer trailers are not as susceptible to this type of damage, or are they?

For the most part, reefers use the same construction method.

Here is a very good YouTube video showing how trailers are fabricated and constructed…

https://m.youtube.com/watch?v=Vz6ejxYZ1b0

Sorry, tried to make it a hot link but it wouldn’t connect.