Question- has any one seen or know of any of the later fabricated drop axles having catastrophic failure? And as failure I mean the axle cracks and rips apart where its welded leaving the upper king pin boss and spindle with hub and tire separated from rest of axle. We have had four such failures. I am going to get some pics to post so it is plain to see. Truck Shop
Pics of axle that broke two months ago and was the second axle in that same tractor. We had the fourth one break to day. Truck Shop
I've never seen that... Who built the axles?
Hendrickson- All of our trucks have fabricated steer and drop axles. Worried we will lose a steer axle and that will be very bad. Hendrickson says we are the only ones having issues-I find that very hard to believe. It's not an over load issue the axles run loaded around 7,000 lbs. Truck Shop
Looks to me like the break starts on the front side next to the factory weld... Design or procedure flaw.
Possible hydrogen cracking next to that weld? Truck Shop
Not sure about that, but it may be a fatigue issue. If the break is starting at the toe of the weld it's a weld or design issue. Most factory welds like that are done with dual shield wire, so I wouldn't think hydrogen embrittlement would be a problem. I'm leaning more to a crappy initial design and you guys are the guinea pig. If your steer axles have a conventional U-bolt mount I bet they are doing fine.
It's hard to really tell in the pictures but it looks like it started at the corner on the bottom edge where the ear comes off for the mounting bracket , stress point that should be a sweeping curve instead of a square angle?
Problem is there all fabricated axles these days, even Watson Chalin is fabricated. But I agree with a crappy design, I thought the bottom piece should be thicker and one solid piece the upper formed piece that forms the tube should have been thicker material. Truck Shop
Have you caught one in the process of breaking, to see where the cracks start? Then you would know which area needs reinforced. I would be hesitant to just start welding fish plates on a steer axle, simply from a liability standpoint. Are they dragging the axle backing up with it down? or having it drag when turning corners and running out of steer angle? or is it just hitting potholes or rough road loaded, twisting them around?
Had a tube gate break like that. The rust starts internally at the bottom. A small defect gets larger & deeper with fatigue, time and moisture. A forensic metallurgist may give you a handle on cause & effect along with leverage on Hendrickson. https://www.failureanalysis.org/forensic-metallurgy
We look the axles over good each time the trucks come in, never have caught one in the process of breaking. And I have no intention of welding on or modifying any axle of any kind, I like to be able to sleep at night. The axles automatically raise when shifted into reverse, operates off the back up switch. The steer angle is not an issue. You raise a good question about potholes and rough road and I'm not trying to be a smart ass but with the roadways in the shape they are in the U.S. most highways are one big pothole. And the axles lift high enough that loading ramps are not an issue with grounding out or high centering causing undo stress. I have some pics of the one that broke yesterday it's an early model with no bottom reinforcing like the updated one in the previous pictures. Truck Shop
Some pics of the one that broke on Wednesday note it is a first generation model, the one above was a redesigned axle. I had a fellow with good fabrication credentials look at both axles today and his opinion was both axles were doomed for failure before they left the drawing board. Truck Shop
That stuff isn't much more than sheet metal to begin with. What were they thinking? That makes those 7K school bus I beam axles look tough.
Well that's very true now just how many of these are running the highways nation wide? Now you folks can understand my concern with crap like this being sold. Federal DOT and any other range of federal safety people should never have passed this crap to be used on the road. Truck Shop
Looks like they all failed at the bracket and/or the bottom plate welded to the flange? Probably the bottom plate since that's what's in tension. I'm really lost as to why they wouldn't run that plate all the way to the transition. After a bit of poking around on the internet, i would be shocked if Hendrickson doesn't own Watson Chalin.
If I remember right hendrickson uses the same beam on the 8-12k drop axles. I'm on the way out to check my 8's now...