question about wheel spacers to increase width of tractor

[Rhino35]

Harry,

I love sea stories like the one about the dual wheel combine's bearing failure. I note you have a Kubota that is about 5% heavier (but 20% more HP) than my Kioti. I looked at the bearing diagram you provided - the vertical load and the cornering load vectors. In another thread a happy customer of Motorsport-Tech.com, which machines custom spacers from blocks of high grade aluminum and has been doing so for 20 years, has a back and forth with some forumites in which the Motorsport-Tech rep states that the way his spacers attach does not unduly stress the wheel bearings. I jumped in that thread and publicly scratched my head because I'm trying to understand not only the physics of installing spacers - and associated risk of catastrophic premature failure and what that might mean on a hillside - but also whether a 3 or 4 inch spacer on each rear wheel even with premature wear/failure is such an enhancement to hillside bush hogging safety that it is a wise tradeoff. So I asked for further explanation in that thread and hopefully we'll hear more. I googled SKF, the swedish bearing manufacturer, and I see there is a calculator, but I am not an engineer and my cursory glance told me trying to calculate an outcome, and make sense of whatever that yielded in terms of risk/life of the bearing, is above my head. Are you interested enough to try and run some numbers for my (our) tractors *grin*? With FEL and bush hog and loaded rear tires I think my tractor is about 6,000 pounds.

I'm finding this subject pretty interesting!

Best,

Rhino

 

[Tollster]

I did the front and rear on my BX. 2.5 on rears and 1.5 on the fronts. I have to disagree with not doing the front extensions. On my BX the front does pivot laterally on the frame, but there are stops. The inherent safety design of many of todays tractors, allow the pivot to hit its limit BEFORE a roll over takes place, essentially turning the axle into a rigid member, however, in many cases, the momentum, leverage, and the angle from the end of the wheel to the center of the tractror in combination to the height of the pivot point does not necessarily prevent the rollover. So adding the extensions decreases that angle once the pivot stop has reached its limit, thereby keeping a lower center of gravity than what was offered from the manufacturer once the limit has been reached.

They essentially extend the point of the fulcrum (pivot) from the wheel, thereby requiring more force or leverage to be applied to create a rollover scenario.

 

[Rhino35]

Tollster,

I agree front spacers would add to stability. Imagine you widened them ten feet, like outriggers, and it is easier to see how a wider track always would add to stability. I'm thinking I'll probably try rear spacers first and see how that feels, then perhaps go with front spacers too. The physics of turning, the load of the FEL, the feedback to the steering wheel, the strength of not only the front bearings but the front axle - seems like more variables up front. I haven't decided and I'm hoping more people chime in with their experiences. Yours is positive. If I may ask...how long ago did you install your spacers and about how many hours of use since?

Thanks for posting!

Rhino

 

[Tollster]

You're welcome Rhino,
Not that long ago I'm afraid, last week. but I too have studied the physics on them and research it off and on for over a year. It wasn't until a few weeks ago that I believed I could really use them. They reduced the sphincter factor considerably. On some side hills I went from a 5 to a 0.

If I could put it in a scale with 0 being the worse, and 10 the best, I would say its between a 4 and a 5. I used to pan out my BH to the uphill side and put out an out rigger if it got real bad. I feel now if I had to do either of those things, it would be a real crisis, and I should not have let it get that bad.
I can understand the additional leverage on the hubs, but if you keep the FEL load within reason, the benefits outweigh the negative's.
The area where we purchased is ALL wooded hillside, and I'm alone 99% of the time, so it was a little easier for me to decide. I'm also dragging timber, and sometimes it tends to roll or pitch downhill. Its those unexpected things that could make a good day go downhill rather fast, not to mention the hidden holes and large rocks in the woods.

 

[vtsnowedin]

Here is a good explanation of why widening both front and rear tread adds to stability.
http://www.nstmop.psu.edu/tasksheets/4.12 Tractor Stability.pdf
It doesn't address the issue of bearing stress or premature failure but as has been said the cost of a few bearings is cheap compared to a hospital stay or a funeral.
I only have 170 hours on my 5045E with the four inch spacers but I'm not too worried about bearing failure as the spacers were factory option and their potential use has most probably designed into the sizing of the tractor bearings. Also being the operator and the payer of repair bills I'm not likely to flog my tractor down a rough road bouncing into pot holes and putting maximum dynamic stress on the rear bearings nor will I neglect to grease them.
Keep it wheels down guys.

 

[Rhino35]

Tollster,

You wrote, "I can understand the additional leverage on the hubs, but if you keep the FEL load within reason, the benefits outweigh the negative's."

This is a great point. I almost certainly won't be using my tractor for heavy FEL work - just the occasional tree limb or buckets of gravel or dirt which I can intentionally downsize with the bearings in mind. The specs on the tractor say the FEL can lift 2,740 pounds - and I never thought about it before your comment - but is that the weight of the load or the weight of the load, plus the loader arms, plus the bucket? I could easily limit anything I lifted to half that weight. It is also not going to be used more than 100-150 hours a year (in all likelihood) and primarily for bush hogging the hills.

Could you please comment on whether you've noticed a change in how the tractor turns? Any difference in how the steering wheel feels?

Your hills sound worse than mine. I posted some pictures on my hill in the "20 degree slope" thread. Way steeper than 20 degrees - and even with spacers I'm not going to go across the steep part. I am interested in increasing he constantly forming and decaying "margin" of safety.

Best,

Rhino

 

[Tollster]

Tollster,

You wrote, "I can understand the additional leverage on the hubs, but if you keep the FEL load within reason, the benefits outweigh the negative's."

This is a great point. I almost certainly won't be using my tractor for heavy FEL work - just the occasional tree limb or buckets of gravel or dirt which I can intentionally downsize with the bearings in mind. The specs on the tractor say the FEL can lift 2,740 pounds - and I never thought about it before your comment - but is that the weight of the load or the weight of the load, plus the loader arms, plus the bucket? I could easily limit anything I lifted to half that weight. It is also not going to be used more than 100-150 hours a year (in all likelihood) and primarily for bush hogging the hills.

Could you please comment on whether you've noticed a change in how the tractor turns? Any difference in how the steering wheel feels?

Your hills sound worse than mine. I posted some pictures on my hill in the "20 degree slope" thread. Way steeper than 20 degrees - and even with spacers I'm not going to go across the steep part. I am interested in increasing he constantly forming and decaying "margin" of safety.

Best,

Rhino

I am not sure if that is the combined weight. But realistically, it's almost 1.5 tons, so ask yourself how often will you be doing that in one lift (an item that cannot be broken down into 2 or 3 lifts?).
If there is one thing that adds up fast I would have to say gravel and stones.
I have not noticed any change is the steering geometry nor the amount of effort required to turn the machine. I have flipped a tractor on its side years ago, and did a two wheeler or two as well (Kubota B7300, tall narrow front end with loader). I can say it happens very fast, the only reason I saved the two wheelers is because I had momentum and was able to correct quickly, transferring the weight to the side that lifted. The other one was a slow speed roll and nothing could save it once it started. I was strapped in and those incidents ensured I reread the 10 commandments of owning a tractor, and a review of various college studies from the Midwest on tractor accidents. I try to read them at least once a year when I get complacent, or when working with a new attachment. Arrogance kills.

 

[redsox1]

I also have an L3800 and added rear tire spacers (from Bro-Tek) this past winter. I did it mainly to increase clearance for snow chains but as an added bonus I do find it increases stability uite a bit, especially when traversing across hills. Fairly easy diy with a couple of helpers on hand. There is a thread on this that I started awhile back if you do a search. Good luck w/ it...

 

[Rhino35]

VTS,

Really good article on tractor safety - thank you. One thing I got out of it - and please correct me if I'm wrong - it that if the rear wheels won't move - frozen, stuck in mud - then the tractor will rotate backwards over itself. I had conceptualized that if the tractor gotten held back - say a bush hog lip caught on a stump - the the tractor would go backwards very fast - but not these two scenarios. And I have to ask...if I have the parking brake firmly set, which affect only the rear wheels, as I am instructed to alway have set in the manual when starting or dismounting, could forgetting to release the brake and trying to move forward also pivot the tractor body up and over? Anyone almost do this with the parking brake?

And it does illustrate nicely how wider front wheels expand the envelope for Center of Gravity. While the pivoting front axle does allow the tractor body to move the CG sideways, when it hits the stop the wider track will still assist the tractor's stability.

I'm new to tractors so I don't know exactly where all the various zerts back by the PTO lead to. There are two zerts, one each, on an outer area of the front axels. How do you grease the front and rear wheel bearings? I didn't see anything specific in the manual, but if I can squirt some grease in there from time to time?

Thanks for joining in the discussion.

Rhino

 

[Rhino35]

Redsox1,

More real world positive stories - appreciated. My dealer is only five miles away and has the block and tackle to make removing the loaded rear wheels job a lot safer than anything I could try in my barn.

Rhino