Tractor tipping - how easy?

Hermio · Jul 28, 2015

The math for this is not difficult. The maximum static angle is equal to 90 degrees -arctan(2* cg/width), where cg is the height above ground of the center of gravity, and width is the distance between contact lines of the tires. For example, if the contact width is 72" and the cg is 48" high (fairly high for most tractors of such a width), the static tipover angle is 36.86 degrees. Trust me, I will never traverse a slope at such an angle! Of course, dynamic conditions are different. For example, if the tractor slides sideways on a slope and hits a rock, rut or tree stump, the inertia may cause a tipover at far less than the static angle. I do not feel comfortable beyond 20 degrees.

vtsnowedin · Jul 28, 2015

Wider is better. Run the math formula above with your wheels set as narrow as possible and then again with them set wide. This is mine set wide with beet juice in the tires. Wouldn't go int the woods with it any other way.

Hermio · Jul 28, 2015

I have the Rimguard in my tires, too. 1300# of it, in fact. But I still don't know the CG. However, I found that the difference between the factory default setting, versus the maximum, which is 3.6" wider, only made 1/2 to 1 degree difference, depending on what assumption you use for CG. I am toying with the idea of adding spacers. Setting the wheels to the max puts the valve stems on the inside, which is inconvenient and also exposes them to branches kicked up by the tires and trapped in the wheel well. (A beef of mine: it seems that all tractors run the wiring for the rear lights up the inside of the wheel fenders. They should be run on top to protect the wiring.)

vtsnowedin · Jul 28, 2015

Hermio said:
I have the Rimguard in my tires, too. 1300# of it, in fact. But I still don't know the CG. However, I found that the difference between the factory default setting, versus the maximum, which is 3.6" wider, only made 1/2 to 1 degree difference, depending on what assumption you use for CG. I am toying with the idea of adding spacers. Setting the wheels to the max puts the valve stems on the inside, which is inconvenient and also exposes them to branches kicked up by the tires and trapped in the wheel well. (A beef of mine: it seems that all tractors run the wiring for the rear lights up the inside of the wheel fenders. They should be run on top to protect the wiring.)

The center of gravity in most tractors is between your feet at the top of the transmission casting. Fluid in the tires drops it a couple of inches and a loader and it's frame raises it a few inches and moves it ahead about a foot.
The valve stems are just as likely to get in trouble with an errant stick pointing inside as they are pointing outside. I don't have any lights mounted on the fenders and wouldn't want wires anywhere near where the winter ice chains are running.
My JD has eight position rims which give you about two feet of difference between narrowest and widest plus I added 4.1 inch factory spacers each side so If I added any more it would need a wide load permit to be hauled down the road.
Doing the math in a static situation I could be on a one to one slope (45 degrees) and still not tip over sideways.
Not going to test it though as I'm too old for crushed bones to heal quickly.

Hermio · Jul 28, 2015

Amen to that, although on my Mahindra, my feet are above the transmission completely. My experience is that errant sticks are far more likely to do damage to a valve stem on the inside of the wheel well than outside, as they cannot fall away; they often wrap up around the axle. I am not so sure the loader changes the height of the CG much. The sub-frame is almost as heavy as the lift arms, and if the bucket is down low, it may serve to lower the cg somewhat, especially if it is a very heavy 4-way bucket, which mine is. (600# heavier than OEM). I have thought about spacers, but I do some logging, and putting the wheels too far out increases axle stress. The Mahindra axles look beefy, but everything has a limit. And the stresses in farm equipment axles are already very high when pulling in low gear.

vtsnowedin · Jul 28, 2015

Hermio said:
Amen to that, although on my Mahindra, my feet are above the transmission completely. My experience is that errant sticks are far more likely to do damage to a valve stem on the inside of the wheel well than outside, as they cannot fall away; they often wrap up around the axle. I am not so sure the loader changes the height of the CG much. The sub-frame is almost as heavy as the lift arms, and if the bucket is down low, it may serve to lower the cg somewhat, especially if it is a very heavy 4-way bucket, which mine is. (600# heavier than OEM). I have thought about spacers, but I do some logging, and putting the wheels too far out increases axle stress. The Mahindra axles look beefy, but everything has a limit. And the stresses in farm equipment axles are already very high when pulling in low gear.

It would vary of course with every make and model but most of them have a attachment point that is in front of the operators feet with some heavy duty bracing under and around the tractors core frame. From there the arms and pistons rise up and go forward higher then the center of gravity of the bare tractor cancelling out the weight of the attachment frame then down to the weight of the bucket which is position dependent but always forward of the tractors bare COG. But you are right hat if held low the loader can lower the COG especially if there is a load in the bucket. But driving around empty with the bucket say a foot off the ground I think in most cases it is a few inches higher then a bare tractor.
I bought the factory spacers figuring that they had done the math and knew what they were warranting. So far so good.

jwmsjwms · Jul 6, 2016

in reading about tipping accidents, it is surprising how many happen on simple slopes that you would not even consider as being a problem and would most likely not even look at at the tilt-meter. ROPS AND SEATBELT!!!!
have a friend that regularly gets tire/tires off the ground and has no protection on his Bota. DUMB GUY, DUMB GUY, DUMB GUY!!!! Was helping him last weekend lifting a log and had to get him to stop so I could cut the thing up into smaller pieces. will be the death of him one of these days. (Maybe I can get him to put the tractor in his will to me!!!!)

czechsonofagun · Jul 6, 2016

Tractor tipping

(cars) tractor tippin (long) - YouTube

Snowback · Jul 6, 2016

czechsonofagun said:
Tractor tipping

(cars) tractor tippin (long) - YouTube

Not what I expected, but pretty funny!

My advice to Jay4200 is to be careful on side hills, (Preferably up and down rather than across if they are steep), no sharp turns at speed on hard pack or paved/concrete roads, and always watch out for unexpected rotten tump wells or ruts/holes. It can be easy it is to tip a tractor if one is not careful.

ROPs and seatbelt worked here. Notice how that front axle pivot is inherently unstable with lateral forces and uneven terrain.

If one operates responsibly there is little risk of tipping, but if you make a sharp turn in medium range and tap the left rear brake to make a slightly sharper turn, then you can end up on three wheels for a brief moment. That may or may not have happened to me after the 4th of July Parade in our neighborhood on Monday...