JD 855 Rear wheel dragging.

[855Idiot]

I was playing around on the lawn this weekend.
Went down a slight hill half on concrete half on grass.
Was in low range just idling down the hill.

One of the rear wheels locked and made a mess of my grass and concrete.
The wheel just didn't want to move, it was happy dragging along.
I stepped down on the diff lock to force it to move but I was a bit disappointed it locked up like that?
It quit misbehaving a bit later...

Did I do something wrong?
Is this common/normal?
Is my diff about to blowup?
Searched the board here but didn't find anything?

Thanks,
Glenn

 

[JerryG]

It is just the nature of the beast. When going down anything steep, put it in 4wd and that will take care of the problem. Also, putting the differential lock on while the tractor is moving can break it.

 

[RoyJackson]

Let me see if I understand this...
You were driving down a slope...one tire on concrete, the other on grass..is that correct?
One tire stopped turning...which one? It sounds like the one on the grass...is that correct?

I could understand one wheel stopping if you lost traction going up that slope, but it just doesn't sound right going down slope.

One more question...were you using your brakes when driving down? If so, were the pedals locked together?

 

[855Idiot]

Right side on concrete.
Left side started on grass then went to concrete.
Left side locked and messed the grass and left dirt & rubber on the concrete.
Reversing didn't unlock the wheel.
Not using any brakes at the time.
Lightly using forward pedal to go slow down a mild hill.

I didn't use the diff lock in motion but, how is the diff lock used/properly applied & released so not hurt the machine?

I have no tractor experience and I'm currently trying to acquire a manual.

...boy these things have personality...
Thanks,
Glenn

 

[RoyJackson]

That left rear wheel should not have locked up.
As to the cause...well, I'm not a hydro guy so I can't help you. I do think you should get that tractor to a dealer soon...before any serious damage.
Before you go to a dealer...try driving down the same route...see if this repeats itself.
If it doesn't...might have been a fluke (WAG on my part). If it does repeat...definitely call a dealer.

As far as using a differential lock, this is what my (790) manual states:

Using Differential Lock
CAUTION: Avoid injury! Driving at high speeds with the traction assist engaged may result in loss of steering control. Do not engage traction assist or turn with the traction assist engaged while operating machine at high speeds or on slopes.

The differential lock is used to provide better traction when rear wheels start to slip. Engaging differential lock will lock right and left side rear axles together and cause both rear wheels to turn at equal speeds for maximum traction.

IMPORTANT: Avoid damage! Using the traction assist function improperly can damage the transaxle:

· Reduce speed and allow drive wheels to rotate at same speed before engaging or disengaging traction assist.

· Disengage traction assist when driving on dry asphalt or concrete.

· Use traction assist only when necessary for improved ground engagement.

NOTE: Turning radius is increased when differential lock is engaged. To assist turning, release differential lock and use turn brake pedals.

Engage Differential Lock:
1. Stop or slow machine movement.

NOTE: Differential lock will remain engaged as long as rear wheel slippage occurs. If tires slip and regain traction repeatedly, hold down pedal with foot so differential lock remains engaged.

2. Push down on differential lock lever (A).

Disengage Differential Lock:
1. Remove foot from differential lock lever.

NOTE: Rear wheel slippage will keep differential lock engaged. Lock will automatically disengage when traction equalizes.

2. If lock does not disengage, depress one turn brake pedal, and then the other.

When one of my wheels stops or slips due to a loss of traction, I take my foot off the throttle and depress the differential lock. Once engaged, I remove my foot from the lock and increase RPM (using the 790's foot or hand throttle). When I say "one wheel stops", this does not mean lock up!

 

[Soundguy]

Since that tractor has a diffy ( right? ) I'm surprised that one wheel locked, with no brake applied.

Soundguy

 

[jd110]

A couple of things come to mind here. If you don't hear any noises from the differential, I doubt you have problems there. If you have your loader on and going down hill, the weight transfer takes alot of weight off the rear especially if you had a load in the bucket. If there is a sideways incline as well as front downhill, The wheel on the upper side could have simply lost traction. Do you have rear ballast? I have run across some machines that have liquid ballast in one rear wheel and not the other. That can definitely cause traction issues. You may simply need to add rear ballast. Lastly, you could have one brake dragging that would cause the wheel to slide in limited traction situations. Try jacking up the rear of the tractor and put your range lever in neutral. You should be able to rotate both rear wheels freely.

 

[Dutch445]

Definately look at your ballast setup, that could be
all that was causing this.
if your hydro pedal was just slightly pushed, you may not
have had the hydro going as fast as the tractor wanted
to go down the hill... so in effect, the hydro was trying
to brake the tractor, and the wheel with least traction slowed
or stopped. was the tractor in 4wd? that may help
in a situation like this, to keep all the wheels moving at the same
speed.
you may find that a little more pedal, and the hydro will keep up
with the tractor's momentum down the slope.

let us know if you have any other quirks with the tractor.,
but like others have said, it may just be normal.

 

[855Idiot]

Ok, I decided to recreate the scene of the crime

Last night, I put the tractor in the same place at the same speed as before...

...nothing happend, it went down the hill as it should have, no dragging, no misbehaving, no nothing.

The tire that locked last time was the inside, up hill tire so simply loosing traction makes some sense. Fortunately it didn't want to repeat the problem so...

I'm thinking it's misbehavior was a fluke.

I'd like to try and see if the rear wheels will spin freely while jacked up in neutral. For some reason I was thinking a hydro tranny, would not allow the wheels should spin freely?

It seems to me that the rear brakes are extremely tight, I hear a groan every time I start to move. It sounds like the brakes having a little battle with the tranny. This is only a start and stop noise.

Thanks,

 

[Soundguy]

see if you have a break dragging..

Soundguy

 

[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?