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Drop axle failure

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Question-has anyone had experience or known of any drop axle failures? Such as cracking and ripping apart/ catastrophic failures. I won't mention the brand name but we have had

four failures one of them today. Fortunately the drivers have caught all of these at very low speeds. It's not an over loading issue the axles pack 7,000 lbs. The company that built them

naturally said we are the only ones that have had a problem. I find that hard to believe, I wonder what the NTSB would say? Pics of the one from two months ago.

 

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Looks like a hydrogen fracture next to the weld area.

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17 minutes ago, 41chevy said:

Looks like a hydrogen fracture next to the weld area.

Interesting you say that because a friend of mine that is a professional welder said the same thing. And where there are four there are more.

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Looks like the tubing wall could be a little thicker.    terry:D

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A little cheezzy & cheap everybody wants light weight that's not where you skimp .

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That is a light axle and if its not watch close this will happen.I think its from hi centering against the stops and also how much air pressure is in the bags.I also think if the axle fails to raise when backing it could help breake it.I would like to have lighter axles but you dont need to be getting off the hiway with these light axles.That looks like a Hendrickson and i am afraid to try to use them that light.

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I agree, depending on how much air in the bags and where it is located on the truck, it could get leaned on pretty hard in certain scenarios.  Only looks like 1/4" wall?  With the leverage and the side load from turning I bet it really works that joint pretty hard.

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I have to ask     who called that cheesy looking pile of scrap an axle?

Edited by carlotpilot

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To answer some of the questions raised above. That axle is a ST13 Hendrickson rated at 13,000 lbs. To be legal on bridge the axle has to 9'6" from center of rear axle to center of tag. Our tags automatically raise when shifted into reverse off the backup light switch. These axles lift plenty high, we have no docks where they could ground out or high center. And as far as cheesy pile of scrap I agree but every company building drop axles have gone the fabricated route, Van Rayden and Watson Chalin also.   Bag  air pressure is 69 to 71 psi on our tag axles.  And no the axle is not so light that if it wasn't raised it would break it, although it's very rough on tires. And again the axle carries roughly 7,000 lbs.  

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Isn't that bag pressure a little high? Don't seem we run ours with that much pressure.    terry:D

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I was thinking same thing run ours between 40 and 50 psi

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26 minutes ago, terry said:

Isn't that bag pressure a little high? Don't seem we run ours with that much pressure.    terry:D

No that's pretty standard psi that we run on a 265 wheel base tractor. Even when all we had were forged axles that was the psi. We net 58,500 with a 24" pin setting on

a 53' three axle trailer and four axle tractor. Actually that's pretty standard psi for any out fit running the same equipment we are. And again the axle is only packing

a rough 7,000 lbs. 

 

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fwiw     this axle that we just had installed carries 8300 pounds with just 15 psi in 2 bags 

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Our drop axles are spec-ed and installed by the factory building the truck. We order them installed so all mounts are huck riveted. And as far as psi in the bags that is well within range for the axle. 

But the question I started this thread with is { has anyone experienced or known of any drop axle failures}. I realize the axle has design faults but there has to be others out there that broke. That's all I'm asking.

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I forgot to say i have seen a few broken and i myself think it may have been air pressure problem.I know each axle design uses differnt pressures but like said that sound to be excess pressure for 7000 lbs.To find out it needs to be put on scales and axled out to find proper air pressure. &0 pls may b good for 13000 lbs.

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58,500# on a 265" wheelbase 4 axle tractor? That sounds like Bridge Formula B, and with only 43,500# allowed on your "tridem", that could be at least 15,000# on the steer axle? Lift the pusher to get some traction, and even more weight could be transferred to the front axle. That's if you can get that much weight transferred forward, unless your landing gear is set way back it's hard to transfer more than a few thousand pounds to the front axle, especially if it's set forward. That leads me to suspect these failed pusher axles are overloaded. Keep in mind too that the drive tandems may be sagging under load at different rates than the pusher- For example a 44,000 pound tandem on steel springs will settle less under load than the air sprung pusher, transferring more weight to the pusher than stationary weighting would suggest.

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I would fathom a guess it all depends on the arm length and where the bag mounts for what air pressure it takes to get it to support a given load.  Shorter length(leverage)=higher pressure.

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at the old job i saw that 4 times out of 15 trucks in 3 years. 

all caused by drivers not lifting the axle when making turns. 

they also would loose tires off the lift axles every 3-4 months due to snapped wheel studs from not lifting on turns too. 

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8 hours ago, tjc transport said:

at the old job i saw that 4 times out of 15 trucks in 3 years. 

all caused by drivers not lifting the axle when making turns. 

they also would loose tires off the lift axles every 3-4 months due to snapped wheel studs from not lifting on turns too. 

We've never lost any tires or suffered any broken studs due to turning. Your not going to turn  tight with a 265"wheel base tractor and a 53' 60" spread 3 axle trailer.

 

 

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i have seen broken mounts and cracked axles none as severe as pictured they did not actually come apart. most that i have seen cracked were after worn kingpins/bushings or stabilizer shocks possibly combined with poor alignment caused them to go into a violent shake going down the road, or drivers backing up with the lift axle down

 

Edited by Ezrider

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I've yet to see one come apart like that. I've replaced a few fabricated steer axles due to wear on the king pin bosses but never snapped right off. Not a fan of those axles. They are throw aways. 

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I've had 20000 pound axles break like that.  I'm convinced someone never had the correct height in the first place.  Lots of geometry in the mounting.   Just an FYI.  Small bags like those on a 13000 pound axles...less volume . Hence the @ 60 psi only yields 7K. Where a bigger volume bag 60 psi might be closer to 20 K

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