Welding Tips and Tricks

Here's a 20+ year-old weld that failed catastrophically... Steve S

Nice, Whats the go with the drive shaft set up?

Mick

The drive shaft (four segments) carries power from a small Kubota diesel near the front of the trailer to a pump at the rear.

Should have been about 2400 RPM.

Apparently, the driveline shop did not balance them.

The torn doubler had a crack in the weld that was missed through multiple inspections and failed after five minutes of vibration.

Steve S

Cool as. Is a set up like that unique to your kind of trailers( liqud h, he), cant say ive sent it before, Not that Ive really looked.

Two bits says the driver over cooled the pump and froze the bearings in the warm end of the pump. Then the instant you put the PTO in gear it finds somewhere for 50 HP to go. I've had the shaft come apart but never ripped the carrier mount out of the trailer though.

@Mike, they're unique to cryo trailers, but other trailers like propane and anhydrous amonia trailers have trailer mounted pumps that run off a PTO on the tractor or an electric motor driven pump. We have quite a few now that have hydraulic driven pumps also. Hydrogen and Helium trailers use an electric motor or pressure unloading mostly.

Len

Hey,

Thanks len, I see the bulk O2truck unloading at work sometimes, but never put any thought into it. I have a mate that used to drive bulk propane, so ill hit him up for more info on our set ups here.

Mick

that's an amazing pic! good thing no one was standing near by.

Braehill wrote:Two bits says the driver over cooled the pump and froze the bearings in the warm end of the pump. Then the instant you put the PTO in gear it finds somewhere for 50 HP to go. I've had the shaft come apart but never ripped the carrier mount out of the trailer though.

@Mike, they're unique to cryo trailers, but other trailers like propane and anhydrous amonia trailers have trailer mounted pumps that run off a PTO on the tractor or an electric motor driven pump. We have quite a few now that have hydraulic driven pumps also. Hydrogen and Helium trailers use an electric motor or pressure unloading mostly.

Len

Len, this happened at our shop, while we were proving the pump circuit on a rehab. This trailer was rotten metal from "GO". I fixed at least 12 vacuum leaks before it saw sandblast and paint.

Right as the pump caught prime, this happened.

Thank goodness it happened in the "proof", rather than after delivery.

Steve

It's best that it happened there and not after the trailer was filled and had to be cleaned up and purged again. And lucky no one in your shop was walking next to it when the shiete hit the fan. I bet there was nobody left napping in the shop after that let loose. At least the engineers were smart enough to put the PTO lever on the opposite side of the trailer so when you put them in gear you're at least a small distance away from the shaft.

By the picture, that looks like a LOX Equipment trailer, and those trailers have seen many days in service. It's a wonder they last as long as they do with as many heat cycles they go through. I know the outer tank doesn't see the extreme changes that the inner does, but it still has to move quite a bit in it's lifetime.

Len

Good eye, Len,

With what little I showed, I'm impressed you recognized it as a LOX Equipment trailer.

On this particualer trailer, I found a stunning number of bad welds, particularly on working doublers, which caused three of us to go over it with a fine-tooth comb, looking for more. Apparently we missed one, and a slightly out of balance drive shaft showed us where it was.

Steve S