Stupid mistake with Diff Lock.

   / Stupid mistake with Diff Lock. #1  

WVBill

Veteran Member
Joined
Jul 21, 2000
Messages
1,505
Location
Whidbey Island, WA
Tractor
Sold my Kubota B6100 when I moved to WA
Yesterday I was helping my neighbor level an area for an above-ground pool. I was pulling my box blade with my B6100 (gear drive) in 4wd around the six foot circle for his pool.

I lost traction so I engaged the diff lock - while truning at minimum radius. I think I might have gone about 10 feet with the diff lock on before I pulled my head out of my anatomy and said oops - turning with the diff lock on is a no-no. Nothing broke that I could tell.

What should I be watching out for? Exactly where would the damage occur if something was damaged? Should I drain and re-fill the transmission?
 
   / Stupid mistake with Diff Lock. #2  
My non-technical answer would be that, if you can feel it engage and disengage, then no damage was done.

With your foot off the diff lock and in 2 wheel drive, turn a tight circle on pavement; if everything feels nice and smooth, you should be okay.
 
   / Stupid mistake with Diff Lock. #3  
My best guess would be that as long as you were in soft enough ground to need the lock engaged in the first place all you would do is spin the inside tire, no harm done. I suspect the only damage might be done on a hard surface.
 
   / Stupid mistake with Diff Lock. #4  
Hello...I'm an idiot, but why is this a concern ??

If I understand the system, the differential lock just locks the two rear drive axles in effect creating a solid axle with both wheels attached. The wheels don't change position relative to the tractor frame...they don't change size... they don't do anything except turn together at exactly the same axle RPM....right ??

This will only cause a headache when you try to turn and the inner wheel ( which wants to travel a shorter distance ) can't.

I can see a problem if you lock in a rapidly spinning axle ( wheel spin ) or if you drive around that way ( tire wear ), but why the concern about mechanical damage ??

What am I missing ??
 
   / Stupid mistake with Diff Lock. #5  
</font><font color="blue" class="small">( turning with the diff lock on is a no-no )</font>

Yes, because when you turn the outside wheel travels farther than the inside wheel and with the differential locked, both rear wheels are going to turn the same number of revolutions, so with one traveling farther than the other, one or both is going to have to slide. That is, of course, if you actually turn since you may not be able to turn; may be instead sliding the front wheels a little sideways. Which one you do, I reckon will depend on whether the front wheels or the back wheels have the most traction at the time. And as long as you didn't have enough traction on the rear wheels at the time to break the differential lock (and apparently you didn't), no problem and nothing else you need to do 'cept maybe try to remember not to do that again. /forums/images/graemlins/wink.gif /forums/images/graemlins/laugh.gif I suspect you and I aren't the only ones who've ever done that. /forums/images/graemlins/frown.gif
 
   / Stupid mistake with Diff Lock. #6  
Once again, Bird comes up with an answer for the question that we can all understand.

Thanks, Bird, for your contributions here. We all gain a lot from them.
Kevin
 
   / Stupid mistake with Diff Lock. #7  
The nice thing about Florida sand is that when I forget to release the diff lock nothing bad happens when I turn. The bad thing about Florida sand is that it's so easy to get wheel spin, espcially with a pretty good box full of stuff in the box blade, that I find myself using the diff lock a lot, which also means that I forget to lift my foot off it more than most. When the sand is really loose (sugar sand), I've actually spun both loaded R4's, and that's with only 18 HP! Guess that's why they make heavy tractors...

Bird's explanation is exactly right. And, you probably aren't going to do a lot of damage if the dirt is soft. On our road racing cars, many people weld the differential so that if a tire lifts off the ground on cornering, there is always one tire getting exactly the same amount of traction. At low speeds on pavement, like in the paddock, you hear lots of tire chirping and hopping and it's difficult to turn, but at speed it hardly makes any difference - when cornering as hard as you can there's always a certain amount of slip, anyway.
 
   / Stupid mistake with Diff Lock. #8  
I was at my dealer's shop today asking about a few things I want fixed before my tractor goes out of warranty. One of them is the diff lock that takes my full 240 lbs. to engage. One of the techs figured that if it decided to stick when it was time for it to unlock I could be looking at a broken axle. /forums/images/graemlins/frown.gif
 
   / Stupid mistake with Diff Lock. #9  
I've had the lever hang up on a bolt head for the foot rest, what happened to me is I couldn't turn, just plowed two furrows with the front tires.
 
   / Stupid mistake with Diff Lock.
  • Thread Starter
#10  
Thanks everyone for putting my mind at ease. The tractor seems fine. Diff lock engages and disengages and no tire scrubbing. Whew! I need to remember not to engage the diff lock when turning - although when turning seems to be the times I most get tire spin.
 
 
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