Broken drawbar... chances a 'pro' welder can fix it

[Sodo]

Dadnatron pics are worth thousands of words. I'm takin' that back that's an easy weld (unless that's your toddler's thumb).
That's a heavy duty unit and a job for an experienced welder of heavy eqpt.

I'm surprised I can't see an incremental progression of the crack. It looks like it happened all at once. I'd have to advise that whatever you did don't do it again. :laughing::laughing::laughing:

 

[ksbrdmkr]

I have had good luck welding breaks like that on drawbars and 3 pt arms with stainless steel rod, a bit more expensive but easy to weld with. 7018 is 70,000 strength and some SS is up to 120,000.

 

[jack707]

Just make sure your welds are sound and bevel the piece before welding.

 

[dragoneggs]

I'm surprised I can't see an incremental progression of the crack. It looks like it happened all at once. I'd have to advise that whatever you did don't do it again. :laughing::laughing::laughing:

Yep that is what I was looking for too. Looks like it fractured with little to zero crack growth!

 

[bigdeano]

How much is a new drawbar? It may well have a higher tensile strength than any weld you could put on there. You don't want something you have to baby or could cause an accident if it breaks.

 

[Shield Arc]

You could always do a spark test to see what kind of metal it is.

 

[CalG]

Yep that is what I was looking for too. Looks like it fractured with little to zero crack growth!

How can fatigue propagation failure be a metric for a single time "strain to yield " event?

Welding can be a useful and safe repair. Preheat for such a large section can't hurt. If the subsequent repair is less brittle than the original part, So what? It will bend INSTEAD of rupturing. Considering the application, I would not suggest this repair for the novice.

Put second pivot in your connection to allow free articulation (pintel hook) . A tow bar is not meant to just drop a pin through unless you are always on level ground. (covered above)

 

[dragoneggs]

How can fatigue propagation failure be a metric for a single time "strain to yield " event?

Metric no... but you are on to it... that is what Sodo and I are talking about. The point is that many failures in the field are the result of a strain that ultimately ruptures the the part but almost always can be traced back to a fatigue crack that weakens the ultimate strength such that an operational load fails the structural member.

 

[CalG]

Metric no... but you are on to it... that is what Sodo and I are talking about. The point is that many failures in the field are the result of a strain that ultimately ruptures the the part but almost always can be traced back to a fatigue crack that weakens the ultimate strength such that an operational load fails the structural member.

How does that influence the prospect of a successful repair by welding?

 

[Sodo]

How does that influence the prospect of a successful repair by welding?

It doesn't. It can be repaired.

Just trying to imagine what kind of load would break that huge member in one whack. And probably shouldn't do that again. All the other things connected to the drawbar felt that load too, lucky if that's the only damage.