Preventing tractor back flip

[arsenix2001]

And as far as "stuff up front" goes I'm not talking about a welded hook on a loader bucket, the front of the frame on most tractors is just as strong as anything attached to the rear of the tractor including the rear axle assembly like the draw bar.

i would differ on opinion to this statement. Most ag tractors unlike industrial tlbs basically hold the front and back together via the transmission to the rear axle, and perhaps loader braces. Tlbs have a dedicated subframe. When using the drawbar, its attached to the rear axle where most tractive force takes place. Pulling from the front with enough rear traction can put undue stress on the tractor. This is a balls to the wall hard pulling senario tho, as in repeated snatches bacwards under heavy power.

 

[LD1]

I'm curious, just how many times or instances do you use YOUR tractor to PULL something that is likely to cause a "back flip"

Not very often. I have been doing what I have been doing for MANY years. Not trying to sound arrogant, but I have never came close. And I have latched onto and skidded, or tried to skid logs that were just too big.

And I usually do it by chaining short and onto the 3PH, that way I can raise the log up out of the mud/dirt, and add a little weight to the back for traction. But with the loader out front, there is little chance of going over. But I an not reccomending anyone else do this either.

 

[xtn]

He made at least one major wrong choice or several smaller ones that added up. The most efficient wrong choice would be to pull from the top link or its mount on the tractor.
larry

Heck, might as well pull from the top of the ROPS. Yes, pulling from above the rear axle is much more efficient way to flip, as the tractor only needs to crawl out from under the attachment point instead of wrapping itself backwards over it.

 

[LD1]

i would differ on opinion to this statement. Most ag tractors unlike industrial tlbs basically hold the front and back together via the transmission to the rear axle, and perhaps loader braces. Tlbs have a dedicated subframe. When using the drawbar, its attached to the rear axle where most tractive force takes place. Pulling from the front with enough rear traction can put undue stress on the tractor. This is a balls to the wall hard pulling senario tho, as in repeated snatches bacwards under heavy power.

BINGO.

While the frame up front may look all beefy and strong, it probabally doesnt go much past the motor. If you look, most tractors transmission-rear end connection is just the castings. NO frame.

And even on the tractors I have seen that have 1/2 frame, there reallt is no good place to even hook without adding some sort or hook or something??

Either way, its just not good on the tractor. But I guess its a good thing you cannot get maximum tractive force by doing this, or you probaballly really mess someting up.

 

[RoyJackson]

Can you please address the part of my post that was addressed specifically to you?

xtn

What was written was all the posts were based upon certain assumptions with little personal experience or any empirical data. That included my posts...not that you posted anything directed toward me, personally. I've never had a rear roll over...have you? The only time my front tires ever came off the ground had nothing to do with pulling from the draw bar.
The professor most likely had more statistical data resulting from actual rear rollovers and greater knowledge of tractor design and dynamics.

Your comment in an earlier post about the professor generalizing...well, what do you think you're doing? Exactly the same thing...generalizing. The difference is the professor has more credibility.

 

[Farmwithjunk]

Have you ever witnessed it happen? On level ground, with a slow and steady pull, and a drawbar mounted below the axle?

I wasn't there to see it happen, but I WAS there to help extricate the trapped victim....

Years ago, IIRC around 1982, while on the Fire Dept, I made a run where a man was killed on a JD4020 that flipped backwards. He was trying to pull a stuck combine out of the mud. All the "rigging" was still in place. He had a piece of cable between the fixed drawbar and the steering axle of the combine. It was roughly 25' long. There was one witness. He was in the cab of the combine. He told us the tractor started pulling, then the combine quit moving after a couple feet, then he looked out the rear window just in time to see the hood of the tractor come up and over. It was a 4020 PowerShift, narrow front, no front weights, but quite a few rear wheel weights..... There was nothing to indicate the operator was jerking on the combine, which was verified by the man in the combine. The tractor was found in 2nd gear, but due to the nature of the rollover, could have possibly been in another gear at the time of the accident, shifter being moved as tractor hit the ground, OR while rescue techs worked to free the man. It was the first rescue run I made where there was a fatality, so it sticks in my mind to this day.

The state medical examiner and the Fire Marshal released their statements a few days after the fact. They had a couple engineers specializing in accident reconstruction to look over the findings. Their comments were included. They said so long as the hitch point on the tractor was above the traction point (tires to ground) there was a possibility of rear rollover. Seeing a dead man pinned under the fender of a tractor every time you close your eyes for a few days cements that finding, let me tell ya.

It CAN HAPPEN (and DOES happen, however rare....) in spite of all the theories stating how impossible this is.

While in my freshman year of college, I was on a debating team. I read (with great interest) a transcript of a debate where a woman argued that the earth was flat. It was VERY convincing. (VERY....) She made her points so convincingly, her opponent finally had no response. So even armed with the unquestionable knowledge that the earth ISN'T flat, a good theory and a better debater can make a case against "facts". I see a LOT of that here in this thread, albeit not quite as convincing...... with the knowledge that back-flipping a tractor (while pulling from a low point) IS possible and has happened. Granted....ALL the stars must align properly, and slow operator response is probably a major contributing factor.....Still, no theories to the contrary will be good enough to win this debate.

 

[SPYDERLK]

I wasn't there to see it happen, but I WAS there to help extricate the trapped victim....

Years ago, IIRC around 1982, while on the Fire Dept, I made a run where a man was killed on a JD4020 that flipped backwards. He was trying to pull a stuck combine out of the mud. All the "rigging" was still in place. He had a piece of cable between the fixed drawbar and the steering axle of the combine. It was roughly 25' long. There was one witness. He was in the cab of the combine. He told us the tractor started pulling, then the combine quit moving after a couple feet, then he looked out the rear window just in time to see the hood of the tractor come up and over. It was a 4020 PowerShift, narrow front, no front weights, but quite a few rear wheel weights..... There was nothing to indicate the operator was jerking on the combine, which was verified by the man in the combine. The tractor was found in 2nd gear, but due to the nature of the rollover, could have possibly been in another gear at the time of the accident, shifter being moved as tractor hit the ground, OR while rescue techs worked to free the man. It was the first rescue run I made where there was a fatality, so it sticks in my mind to this day.

The state medical examiner and the Fire Marshal released their statements a few days after the fact. They had a couple engineers specializing in accident reconstruction to look over the findings. Their comments were included. They said so long as the hitch point [[on the tractor]] was above the traction point (tires to ground) there was a possibility of rear rollover.

It CAN HAPPEN (and DOES happen, however rare....) in spite of all the theories stating how impossible this is.

While in my freshman year of college, I was on a debating team. I read (with great interest) a transcript of a debate where a woman argued that the earth was flat. It was VERY convincing. (VERY....) She made her points so convincingly, her opponent finally had no response. So even armed with the unquestionable knowledge that the earth ISN'T flat, a good theory and a better debater can make a case against "facts". I see a LOT of that here in this thread, albeit not quite as convincing...... with the knowledge that back-flipping a tractor (while pulling from a low point) IS possible a has happened. Granted....ALL the stars must align properly, and slow operator response is probably a major contributing factor.....Still, no theories to the contrary will be good enough to win this debate.

How long and high was the drawbar? Did it bend upward? Im not asking for specific measurements, but instead to hilite parameters that matter. The explanation given by the examiners is not supported by Physics. I expect the true cause escaped everyone.

Since it happens under some sort of unknown condition, I wonder why a demonstration of the phenomenon is not done with real documentation so wed be able to see the problem instead of attributing it to capricious occurrence. Its just magic ...

I would sure like to see that flat earth debate.
larry

 

[tmajor]

Reading that story, brings a couple of things to mind.

Thinking of my own experience, I'm guessing that many of us, who have pulled such things, may have come closer to flipping the tractor, than we realize.

I'd say that the fact, that the combine stopped, was the key to the accident. My mental process always seemed like, "start slowly, so as not to break traction", then once you are moving, "give it some gas to keep the momentum up". At this point, a sudden stop, caused by the pulled object, could be "sudden death" or injury (if you are lucky).

 

[SPYDERLK]

Reading that story, brings a couple of things to mind.

Thinking of my own experience, I'm guessing that many of us, who have pulled such things, may of come closer to flipping the tractor, than we realize.

I'd say that the fact, that the combine stopped, was the key to the accident. My mental process always seemed like, "start slowly, so as not to break traction", then once you are moving, "give it some gas to keep the momentum up". At this point, a sudden stop, caused by the pulled object, could be "sudden death" or injury (if you are lucky).

Absolutely. Could cause a very quick back tip that proceeded past the driven point soley by inertia.:thumbsup: ... altho quick deceleration of the tractor mass from the height of the drawbar favors a quick transient shift of weight to the front. But with the engine at full song its ready to grunt and rare it up fast.
larry

 

[tmajor]

Absolutely. Could cause a very quick back tip that proceeded past the driven point soley by inertia.

Actually, in addition to "inertia", if the combine stopped and the tractor tires stopped due to good traction, the tractor drive system would actually power the tractor mass backwards around the drive axle.