JD 855 Rear wheel dragging.

[zzvyb6]

Answer is quite simple. They call it a differential because ...

It differentiates !

That means for a unit rev of the tranmission/drive shaft, the average of the revs of the left wheel and the right wheel must be the same.

So: input_rev = (L_rev + R_rev) / 2.

So, in your case, the input_rev was low and the left wheel was stopped (L_rev = 0). This means the other wheel (on concrete) was actually going twice its usual rpm to satisfy its mechanical action. Yes, a brake drag friction level can cause this, but I believe its simply the effect of the tire-on-grass slip friction being low enough so the left side side-gears in the diff. housing locking up. This is how a limited slip diff works. Check the oil level in the diff. Could be low enough for the side gears to be dry but the pinion lube to be ok.

If you jack up the entire rear axle housing, and you spin one wheel clockwise with the input_rev = 0, (engine off, xmission in any gear) then the diff equation says the the other wheel rpms must be -1 (i.e. it turns the other way) to satisfy the differentiator equation.

The differential is there to minimize tire scrub for sharp turns whereby the outer wheel must turn a faster rpm than the inner wheel without scrubbing your lawn, field or wearing the tire tread from scuffing.

 

[855Idiot]

Update,

I was clearing two to three feet of snow over the Hollidays.
After an hour or so, I noticed the same rear wheel dragging.
I had to use the diff lock to make the wheel move in the snow.
When I was not using the diff lock, I could feel the tractor pulling sideways.
Because the snow was so deep, ice built up in-between the inside of the rim and the tire.
I believe that the ice buildup combined with the wheel acting up caused the bead to pop on the rear wheel.

It was 9 degrees at the time.
I had to remove the wheel and warm it by the fire to melt the ice and get the bead to hold air again.

The Tractor has not really been used much (4hrs) since this thread began.
I've decided to replace the tranny fluid and filter before I use it again.

Was this just cold weather, deep snow and bad luck combined or is there something more sinister going on with my tractor?

Any thoughts?

 

[yankeerider]

As Dutch455 asked earlier, what is your rear ballast situation?

I really think your earlier problem was nothing more than weight transfer off the rear wheels and the tractor wanted to roll downhill faster than the hydro wanted it to. On my property, I descend a very steep hill and, even with a full ballast box, it will "lock" a rear wheel due to poor traction and "light" rear end. It's far worse if I have the FEL on and no ballast because I'm gonna pick up an implement at the bottom of the hill. Engaging 4Wd before descending fixes this problem every time.

this second occasion- are you sure the tire was at full pressure before you began working? I've spent hours in deep snow without popping a bead. I suspect your tire was real soft to begin with, you lost the bead because of low pressure, and that let the snow/ice in. Once no bead, rolling resistance was high and tire didn't want to turn.

i don't think you have a sinister problem.

 

[Dutch445]

Just one more thing to check, when you brought
that tire in to fix it, did the bead area seem ok?
were you able to dry it good, and get a good
tight seal?
we have seen wheels spin inside tires, and that
could have been what was happening in the snow,
your axle and wheel could have been turning,
but the tire wasn't. ( i have had that happen
myself, and thought my tranny was dead, until
i noticed the liquid ballast running out of the inside
of the bead)
if your tire has had any slime, or other stuff put inside,
that can also contribute to a tire that will slip on the rim

let us know what you found

 

[Soundguy]

I still vote for jacking the rear up locking the pinion, and seeing what the diffy does..

soundguy

 

[855Idiot]

When it happened this time, I had my box scraper on the back, as I found it really handy for dragging and pushing snow. The box weighs #500.

I didn't check the tire pressure before starting but it sat level and worked fine for sometime before the bead went.

By the time I put it away I had to use the diff lock most of the time to get it to turn both rear wheels.

Is it possible I have some sort of brake issue affecting the tranny?
Frequently there is a groaning sound as I start out after the tractor has set for a while.
Is is possible to back off on the brake on one side?

I'll jack it up this weekend and see what the wheels do.
I also plan on doing the tranny fluid and filter.

What else should I do...remember, I'm an Idiot!

 

[yankeerider]

...By the time I put it away I had to use the diff lock most of the time to get it to turn both rear wheels.
...remember, I'm an Idiot!

Well, that doesn't sound right, if that tire was wanting to skid everywhere after reinflating unless you had the diff locked.

Time to check that brake.

 

[855Idiot]

When I re-inflated the tire, I had no gauge.

I had to put some PSI's in it to seat the bead.
I then dropped the pressure till it "looked" correct.
This could have also been a factor/after the fact.
I'm sure the tire still has more PSI's than the other.
But even with more pressure, it still dragged...

 

[Tractors4u]

Is it possible I have some sort of brake issue affecting the tranny?
Frequently there is a groaning sound as I start out after the tractor has set for a while.

It does sound like a break problem. You say that you have only put 4 hours on the tractor since you originally posted this problem, correct? If the tractor isn't used very often, there could be some rust in the brake drums causing them to drag.

 

[dfkrug]

Is it possible I have some sort of brake issue affecting the tranny?
Frequently there is a groaning sound as I start out after the tractor has set for a while.
Is is possible to back off on the brake on one side?

I think one brake is dragging. Yes, you can adjust the brake pressure
applied by each pedal separately. There is an adjustment on each
rod. Perhaps you got snow/ice packed in around the brake actuator lever
on one side of the rear axle?