Frozen Brake and Ruined Differential

Discussion in 'Trucks [ Eighteen Wheelers ]' started by fatdog, Jan 16, 2012.

  1. fatdog

    fatdog Bobtail Member

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    Dec 10, 2011
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    Well, it appears I'm being blamed for ruining a differential. Just wanted some knowledge on the topic from a mechanic so I know what I'm being blamed for in better technical detail.

    I picked up my tractor at a CAT shop where they had been working on a boost sensor problem. It sat there for a couple of days, during which it rained, snowed, and got pretty cold. Apparently when I drove away, the wheels on the right of the front tandem were locked by a frozen brake shoe.

    I noticed a slight drag after getting on the road, but it was so slight that I really didn't think much of it since the tractor was cold. I could not see that front right wheel clearly enough to notice it wasn't spinning because of the splash guards and position...just not a good spot to see that position. Anyway, got two miles down the road and the "drag" seemed to increase and I started looking more intently at all my gauges, with no apparent issues, no smoke or weird dragging or screeching sounds...just an increased sense of being held back. Then I started losing power to my wheels, had a chattering-jerking thing happen, lost most/all power to the wheels, pulled over. Still did not know what had happened until the tow truck showed up. He was able to watch the brakes as I released them, and that's when I realized what was happening.

    The truck was bobtailing, the road was wet. I may have stopped sooner, but still wouldn't have figured it out in all likelihood, since I couldn't safely release the brakes on the side of the road and go out and look at the shoes.

    Anyway, how likely is it that a supposedly healthy power divider/differential will be destroyed before it would pull the brake shoe loose under these sorts of conditions? I'm just trying to reconcile in my mind how something as powerful and tough as the torque running out through the axle would fail to break the ice before breaking the differential/power divider.

    I hate to put my ignorance and stupidity out here like this, but it was pretty traumatic for my ego to realize I had been driving around with a frozen brake shoe, and I am supposed to be a good experienced driver. Anyway, flame away if you must, but some education about the issue would be nice. Thanks
     
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  3. JohnP3

    JohnP3 Road Train Member

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    Feb 21, 2010
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    First off you will destroy the differential having one wheel locked.
    I am a mechanic and use to explain to drivers, that they should always back up first under a trailer to be sure the 5th wheel is locked then tug test it, then when the truck is at about 5 miles an hour coast to be sure everything is freed up. If it stopped their was a problem.
    I use to have an area in the industrial area that had a slight hill, If they figured there truck had a power loss problem they would take the loaded truck there, before they came to the yard, crest the hill at 30 MPH and coast the telephone poles were marked with letters, they told us were they got to and we would have a better idea whether the problem was something draging or an actual power problem.
    Just a thought!
     
  4. Big Don

    Big Don "Old Fart"

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    I would think that if you notice anything out of the ordinary, and a feeling of a slight drag is out of the ordinary, you would have stopped and at least tried to check it out. This is NOT a flame, so don't take it that way. But if something seems wrong, it probably is.

    You also show 9 years driving in your profile, which means you've been around long enough to know that if something happens, it is ALWAYS "the driver's fault." About all you can do now, is to learn from this and go on with your career.

    How badly is this going to hurt you with your company, if at all?
     
  5. Heavyd

    Heavyd Road Train Member

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    Yep, sorry to say, but you did smoke the diff. The differential spider gears are spinning when one wheel is turning faster than the other. In your case one wheel wasn't turning at all so those little spider gears where just-a flyin'! They aren't designed to spin like that for too long because they are just splash lubricated, but when they are spinning they actually throw the oil out and away from themselves so they get oil starved and burn out pretty quick.
     
  6. bender

    bender Road Train Member

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    Don't Kid Yourself
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    These things happen every day, especially in winter...now you know, suck it up and move forward the wiser. Everyone of us has learned our lessons along the way.
     
  7. truckbiz

    truckbiz Light Load Member

    Heavyd covered it pretty good for you, IMO the diff should be easily repaired, I doubt much more than the cross and spider gears were damaged.
     
  8. Wildcat74

    Wildcat74 Medium Load Member

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    Almost had the same thing happen to me once, though I was able to catch what was happening within about 200yds because the ABS light came on. Tough situation and accidents happen but you've got to learn from it as others said. Don't beat yourself up over it too much!
     
  9. ENR

    ENR Light Load Member

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    Oct 8, 2009
    Ontario
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    Great thread..

    This is very easy to have happen and I appreciate you putting it out here. Just about any of us could have been caught by this to some extent.

    I'm going to have my drivers read this.
     
  10. Allow Me.

    Allow Me. Trucker Forum STAFF Staff Member

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    Rancho Mirage, Ca.
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    A good driver is aware of things with his equipment. The binding or dragging should have been a warning to you, STOP immediately and have a look.
     
  11. fatdog

    fatdog Bobtail Member

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    Well, I still feel dumb, but it is what it is. I should have stopped sooner, but it's too late for that. Anyway, The shop is saying that it's a $3,400 repair and they are trying to make my boss pay for it...which could trickle down hill...

    My boss is telling them that the average life for a diff/power divider is like 450,000 miles, and this unit has 380,000 on it...it should be discounted. (We lease this truck...that's why he's using that argument, hoping to get a "depreciated" cost). Their salesman was following me on this trip and never noticed anything either from behind me, so he is also using that argument. The salesman also seems to be on our side, so perhaps the cost won't be too crazy.

    I was up front and honest with them about everything, and if it comes down to it, I'll pay for my mistake. Feeling dumb and then paying stupid tax is tough, however, so I am hoping to avoid paying much for this one.

    Thanks again, and y'all take care in this cold weather.
     
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