Power steering loosing power

[wh_bob1]

I have a 2000 JD4100 hydro with 410 loader with 150 hours. At about 10 hours, I noticed that when I tried to back up to attach a 3ph attachment the steering would not function at the end of the ranges, making it nearly imposible to position the tractor's 3ph arms. Dealer changed all fluids - problem persisted. Dealer checked pressures - within range but on low side. JD finally asked them to add shims to boost the ps pressure. This solved the problem. However, this summer, when I was mowing a very steep berm laterally, I did notice some steering drift and plan to have it checked out. I think that the 4100 is overall one of the most trouble free models.
I hope this helps. This forum was a big help when I was trying to decide what cut to buy. Good luck!

 

[slefevre]

Bigpete,

The surface was dry blacktop.

slefevre

 

[BillyP]

In my mind, I can't see it being anything other than a weak pump. The only thing that troubles me with that thought is it happened right after you changed the fluid. The size of the back tires ain't gonna matter, not with the steering. I think your dealer or his mechanics don't know what they are doing, or they would have figured this out by now. As far as the JD dude, he's probably a company man, the dealer fed him a line of BS or he's fresh out of college or don't know ****.

 

[bigpete]

Hi again, Dennoace:

You mentioned: <font color="blue"> In general I have ABSOLUTELY no idea what anyone is talking about when discussing how in the world two larger rear tires will affect steering to this degree. The reason the muscle cars would be steering funny is because the unreasonable rear lift (usually several inches straight up...not just a larger tire) would completely change the F/R weight ratios not to mention a host of other engineering properties that are present on a car which is 98% on pavement vs. a tractor with a couple more inches of diameter in the rear. And the alteration would affect cornering, etc not so much sitting still and turning the wheel in the parking lot of the local drive-in. That problem would have more to do with front tires being swapped for much wider ones, etc.
</font>

The reason we are discussing this possibility is because this is what the JD RM has told JClark. I have a hard time grasping the magnitude of a couple of inches thowing off the "caster" of the front steering dynamics, but I also can't rule out the possibillity that this has something to do with it. The rest of us 4110 owners with stock wheels are not having the problem.

You don't need to take my word for it that creating a negative caster condition in the king pin of a steering mechanism will make it more difficult to steer. It's more stable in cornering, but more effort is required. If our tractors are designed with a near-neutral caster, even this small amount of lift from the rear, coupled with a load on the front, could throw the caster into enough of a "negative" angle that the steering effort could be increase exponentially. It's an engineering fact. Perhaps it's just magnified with all the conditions JClark is creating.

Anyway, you can do a Google search for 'Caster Steering" and get a bunch of very technical feedback. Racing engineers write about it all the time. The Hoosier Racing Link will lead you to a basic definition, and the Hunter page will discuss it on a more technical level. It's real...

Hoosier Racing -- Look up 'Caster'

Hunter Undercar

 

[JClark]

slefevre,

Thanks for running the tests on your 4110. According to my 410 manual the ballast box filled with sand is 528#. I'm guessing your ballast box filled with stone is less than that, maybe 400#. A bucket full of wet snow is a tough one. Figure a 55 gallon barrel full of water is about 500#, so maybe big scoop of wet snow is 300#.

Given those weights, pre 60 hours, my 4110 would turn lock to lock on dry pavement with little effort, ballast up. Now, same setup, it won't turn at all past about a half turn of the steering wheel.

Your results with the front tire pressure are interesting. I am beginning to believe, based on your tests and the experience of wh bob1 with his 4110, that the hydraulics run very close to capacity for steering. Just a little difference in wear, setup or manufacturing tolerances can cause steering in loaded conditions to be difficult.

I don't believe the 4WD lag issue is material to the steering problem. The pump running the drive train is entirely separate from the pump running the steering and other hydraulics.

As for the status, today I carried the tractor back to the dealer for testing. The dealer called and said they have finally received the flow test equipment and even offered to come get it. I don't leave the tractor at the dealer for a couple reasons. It is my tractor even though I am still making payments on it to JD Credit. I don't like having it left out in the weather and I don't want one of the adolescents who work their to go hot dogging around on it. Which is why I politely refused their offer to pick it up and instead carried it to them myself. I am funny that way about my toys.

I made it very clear that I am prepared to return the tractor to stock condition for the operability tests but they said not to bother just yet. I think I mentioned upthread that I have a line on some stock 4110 R4s that are the same size as the stock R4s on the 4110.

wh bob1, when you said 'add shims to boost the ps pressure', do you mean shimming the relieve valve?

 

[JClark]

By the way, thanks to all for commenting on this issue. By the time this over with we will all know more about steering JD 4110s than any JD dealer in the world. Hell, maybe we already do.

 

[JerryG]

The steering is self bleeding, like the hydraulics.
The size of tires no problem or virtually none in two wheel drive. A FWA compact is designed to have the front tires rolling circumference 3-5% more than the rears, this produces a lead situation when in FWA. When in FWA and the rear tire size is increase to a point where the lead % of the front to rear is decrease to a point to where it is neutral or negative, that is when the front tires are in a lag situation. When in a lag situation, the entire drive train (including the steering) is placed under stress. The front end is now pushing instead of pulling (or leading). This is make the tractor or truck or anything with FWA to steer hard.

 

[jrlichina]

Another word on caster. Proper caster promotes stable steering characteristics and aids in self-centering of the steering wheel. Caster is important on higher speed vehicles like cars, trucks, and obviously race cars, but it is NOT an issue as it pertains to CUTs. In general caster comes into play when the vehicle is in motion not in static situations. The only time it would have an effect in a static situation is if the caster angle was changed drastically(greater than +- 20 degrees). At extreme caster angles the force required to turns the wheels will increase. This would require those rear tires to be about 8-10 inches larger in diameter, which is not the case. Remember this tractor steered fine before the fluid change! There is some problem in the steering system(I also believe his front tire pressure is too low). I still think the most likely cause is some contaminent or foriegn object in the system that got in during the fluid/filter change. It only takes a very small particle or metal chip to block a passage or interfere with a relief valve. This dealer clearly has incompetent mechanics.

JerryG, nice simple explaination of lag/lead conditions. Only one thing to add is that this is valid only when the vehicle is in motion, not in static situations.

 

[JerryT]

Jerry G
Your point is well taken, plus as I mentioned in a previous reply on this subject, the technical manual indicates that different tire sizes could be the problem. However, shouldn't it go away if you take it out of 4wd?

 

[wh_bob1]

I think that is the valve that was shimmed. I think that it is front of the operator's seat, somewhere near the drop-rate valve. Also, I have R4's. When I had my problem, I had the loader mounted with nothing in the bucket. The dealer also had to get the instruments to measure the flow/pressure. I remember only one other poster on this board or on Compact Tractor Board in the MidWest who had a similar problem. Out of curiosity, do most larger farm tractors with hydro's have a combined hydro/steering resevoir?
Let me know if I can answer any other questions.