How to Break a Kenworth Sway Bar

Horse Plains Drifter

The bar section in the picture is 2" in diameter, and about 18" long. The complete bar is "U" shaped and about 40" wide and weighs around 70#-80#.

It has been raining a lot here, about 30" thus far this year. The woods are wet, and soft. The truck got over too far trying to get around a pickup that was parked in the way. The soft shoulder started to give way, and there was no coming back. In slow motion the truck just laid over. No apparent damage besides this sway bar, and the right hand mirror, and driver's pride.

No, it was not me

Mr. Perfect

I think a more relevant post would be how NOT to break one.

select-fire

Hey Boss the truck rolled over again

montanajoe

That's a lot of force to snap that.  Glad no one was hurt.  Guess if you gotta put it over, soft and slow is the way.  

TRAP55

On the plus side, the driver did a damn fine job chaining down that load.

Glad the driver is okay.

SCOUT5

TRAP55 said:

On the plus side, the driver did a damn fine job chaining down that load.

Glad the driver is okay.

That's the first thing I noticed.

Don McManus

That bar was cracked long before it broke. Possible that it finally breaking put him in the ditch?

BobJudy

Don McManus said:

That bar was cracked long before it broke. Possible that it finally breaking put him in the ditch?

Yup, the corrosion evident in 90% of the break seems to show an old crack that finally broke all the way. Bob

toad67

I can hear the shovel operator cussing from here......

buddyb

Logging and dump trailers are hard on trucks,especially suspension components.

Horse Plains Drifter

BobJudy said:

Don McManus said:

That bar was cracked long before it broke. Possible that it finally breaking put him in the ditch?

Yup, the corrosion evident in 90% of the break seems to show an old crack that finally broke all the way. Bob

The rust in the break is simply from the bar laying out in the back of the pickup for 3-4 days. Stuff rusts that fast around here. There is one funny looking spot in the break that I do not quite get though. It is that thumb nail size spot that is very evident in the second picture of the bar. The spot is completely black in color, but no old cracking radiating out from it. The driver said that the bar let go when the truck was tipped way up, like 25°-30°. He said it let go with a bang that sounded like a rifle shot. He said he thought the frame broke when that happened.

CaptFun

Mr Perfect can give you the full run down, but the short answer is the rust colored area is long term fatigue  cracking and the "bright" area is fast fracture during the final failure.  We had a similar failure last week on one of the auger screws that remove lead from one of our 25 yard ranges,   2" diameter shaft > 85% fatigue, <15% fast fracture.   Still working on finding  the root cause here

jimdeere

RCFA conclusion-Driver error.

elubsme

Wow, sure glad it wasn't you.  I broke two torsion bars on a '76 W 900 but was going slow both times.  Retirement is good, my friend.  

kannoneer

Oh, it broke because of the wreck and not before? Well, when a loaded semi goes over, the stress can break a lot of heavy steel parts. Not really a surprise there. Now,  if it snapped just rolling down the road, that is a whole different deal.