Slopes and tractor tilt

[SPYDERLK]

Tell you what...I've got to mow on Sunday (08 May) if it dries out enough. It needs mowing but too wet today. I have a pretty decent slope I mow across (8-10 degrees or so, measured quite a while back by a tiltmeter).
I know the slope is safe from mowing it the last 10 years. I'll get off my tractor and look at the front axle. I don't normally carry a camera, but I will get a pic if possible.

Sounds like a great idea. I'll do the same here tomorrow (trying to keep the tractor off the grass for one more day - it's like walking on a sponge here.)

If you've got a particular slope you want, I'm sure I can find it somewhere around here. The steepest I drive on regularly is 22 degrees - straight up & down only. I'm chicken. I do have some 25+ degree slopes with trees on them and I'm not sure how I'm going to get the lumber this spring - I may just use my favorite 1/2 hp tractor.

I will remain a vicarious member of the empirical study group. ... It sure would be nice if the stops were adaptive to slopes, acting to damp and limit downhill pivot. Tractor designers could invent this feature. It would make the tractor much more stable.
larry

 

[RoyJackson]

I will remain a vicarious member of the empirical study group. ... It sure would be nice if the stops were adaptive to slopes, acting to damp and limit downhill pivot. Tractor designers could invent this feature. It would make the tractor much more stable.
larry

That's true...but what we might need is a funeral director...

Boy, a beautiful day in south central PA!!! Hope it holds up until tomorrow!!!

 

[Jerry/MT]

I agree that we'll disagree.

The only way to hit the stop is to 1) drive across uneven ground or 2) start a roll. No matter how steep the slope, if the slope is flat (like a 1/2 open hardback book cover) then you'll be dead center on the front pivot - equidistant from both stops.

So no, you don't roll on every slope because you don't hit the stop on every slope. I was responding to someone earlier who talked about the front axle stop arresting a roll - and my point is that once a roll has started because of the usual reasons*, it's rare that the front stop arrests the roll.

*usual reasons include - hole, bump, sudden turn, load shift, etc. All of these things lead to a sudden change in the stability of the tractor. Rolling because you just flat out exceeded the tilt limitations without turning, hitting a low spot or high spot is pretty rare, IMHO.

You gave a good example of what I was trying to say.

Simple static stability gives a lot of insight to the problem of longitudinal stabilty (roll) for a tractor. It is not the final answer because there are many variables but they all are perturbations of this simple stability relationship. That's why in my first post I would not consider using the calculated max slope as a limit. I would use 80% of that angle because of the effects of speed and slope roughness, uncertainty of the cg due to added equipment, etc.

The front end loader is a destabilizer in general because it raises the roll center. I don't see any data that supports the contention that the loader does not change the roll center of the tractor when installed. When I installed a loader on my Ford 4610, I could pick up each half of the side mounts. They were about 150#'s each. The loader main frame was 850# and the bucket was about 200 #. Most of the weight of the side mounts was above the tractor cg as is the main frame. There is no way that the cg was not raised by this installation. My NHTD95D has an 820 TL loader and has a cab. This loader installation may actually stabilize the tractor because the cab raises the cg and the loader appears to lower the cg, but I can't be sure. I'm sure without the cab, the loader would decrease the stability of the tractor.
Putting a balanced load in the bucket (balanced laterally) and carrying it low can be stabilizing (relative to the no load in bucket case) IF it lowers the verticle height of the cg. If a load, (like a big rock) is carried low in the bucket and shifts to the downhill side of the bucket, the cg will shift to the down hill side proportionately and reduce the stability reealtive to the centered load case.

Forget about the front axle helping you very much. It can't do any good until it hits something on the tractor structure to stop its rotation. By then, the rear wheel is off the ground and you're in the roll.

All this simple analysis does not consider additional loads from bumps and holes along the slope which are also destabilizing. There is also a lot to be said for watching your speed when traversing a slope.

If you read the many pages of warning in the operators manual for a tractor and those for a loader, you will see these very same warnings.

 

[RoyJackson]

You gave a good example of what I was trying to say.

Simple static stability gives a lot of insight to the problem of longitudinal stabilty (roll) for a tractor.

Spoken like a true retired aeronautical engineer...

 

[SPYDERLK]

That's all very nice...why don't you run your tractor across a slope too...that way there can be three of us with real world input rather then the theoretical.
Get pics!

Now, if only I can convince TripleR to do it too...

What is this? ... a vote? The results will and have been well foretold by the theoretical. They will be substantially identical to North Countrys description at the depth to which he addressed it. Beyond that depth there will be variance according to the exact scenario. Such variance will be compatible with theory and easily accounted for by going deep enuf into theory to cover the specific case.
larry

 

[Jerry/MT]

Spoken like a true retired aeronautical engineer...

Roy,
Is that good, bad, neutral or just what is??????


(Actually my specialty was propulsion aerodynamics but I got interested in tractor stability when I started ranching; kind of a self preservation thing.)

 

[RoyJackson]

Roy,
Is that good, bad, neutral or just what is??????


(Actually my specialty was propulsion aerodynamics but I got interested in tractor stability when I started ranching; kind of a self preservation thing.)

Not bad at all!!

One of the jobs I used to do was translating the engineering jargon to something that could be used by the production and other non-technical folks.
Technical writing was one of the best courses I ever took...that and psychology.

Anyway, after reading the technical jargon, I figured you had to have an engineering background of some sort...so I read your profile.

 

[RoyJackson]

What is this? ... a vote?

Negative...the sample, so far, is a small CUT (the 2305) and a large frame CUT (my 4400).
Right now, we have too many variables (how North Country's slope varies as it's traversed vs my slope and it's corresponding variations) and too small a sample size. That, in addtion to variables we cannot account for (materials and design, primarily) since none of us have access to that information...

Although we'll run this little test, it's not particularly scientific. It'll be what we call "anecdotal data".

Now, if you really want to prove out those theories, you'd need to do some computer-aided work.
Otherwise, this thread has been a pretty interesting theoretical discussion with very little empirical data to back it up (and that includes all the posts, including mine).

BTW, you responded to a post I revised extensively...I thought the original post was a tad rough and wisea$$.

 

[Jerry/MT]

Not bad at all!!

One of the jobs I used to do was translating the engineering jargon to something that could be used by the production and other non-technical folks.
Technical writing was one of the best courses I ever took...that and psychology.

Anyway, after reading the technical jargon, I figured you had to have an engineering background of some sort...so I read your profile.

Who did you work for as a tech writer? You're absolutely right! Engineering has it's own language and it specialized depending onthe specific technical area. psychology is also useful for dealing with engineers!

 

[TripleR]

Roy, I would like to help you with your "research", but I am now afraid to get on my tractor.

Actually I will be mowing pond levies next week with our M8540 with FEL and a pull type Woods DS1260, been working on some minor slopes this week with my L5030 HSTC hauling full buckets of crushed rock. In theory the full bucket is supposed to help stability, but it sure raised the pucker factor for me for some reason.

Please don't use any more big words, I can't keep up, my minor was in Psychology and it isn't helping.:laughing: