Tractor Rollover Myths and Facts

[RoyJackson]

"As to the bushog value against rollover - Even tho they have the top flex link, or sometimes a chain that would thwart application of compressive forces entirely, you still get earlyearly warning and a good rollback pause from that way back tailwheel touching."

One other thing...that driven PTO shaft is only going to collapse so much and would (in my limited reasoning skills) impede a full roll over even with chain used for the top link (or, in my experience, a disconnected top link).

Of course, even if the implement prevents a full roll, you'll probably be killed by being impaled by the implement's 3PH framework.

 

[scott_vt]

Does anyone know of a back flip actually happening in a tractor pull?

On the other hand, why do the front wheels rise somewhat, and then no more?

Tom

Afternoon Tom,
To the best of my knowledge, no matter where you go to a tractor pull, even back woods pulls, you have to have wheelie pads or bars whatever you want to call them ! Depending on who is sanctioning the event, they stipulate what safety equipment is necessary ! I am not an experienced puller, these things are what I have observed at events that I have attended.

Yes, the tractor front end will rise somewhat, but only until the rear pads contact the ground.

 

[TMcD_in_MI]

- - Ever had a situation where you dont know exactly what is wrong, but you know its not right. Figure 5 in the Tractor Overturn Hazards link in post 18 presents just such a situation for me. The "angle of pull" is a puzzler. I can discern neither its intended meaning nor its true meaning.

Larry - I am with you on this, because it makes no sense to me either. The dashed line doesn't represent any real force that I can imagine. I wonder what the author was thinking?

Tom

Later Edit: I just emailed the author. I'll let you know if I hear from him.

 

[Farmwithjunk]

Does anyone know of a back flip actually happening in a tractor pull?

Tom

Either 1974 or 1975, National Championship Tractor Pulls, Louisville Kentucky, during the National Farm Machinery Show. A "Hot Rod" tractor flipped backwards and on to the front of the sled, pinning (and killing) the driver. It was the reason for the NTPA adopting the wheelie bar rule.

With high horsepower pulling tractors, you have factors like wheel speed, inconsistant traction, and "never back off" competitive nature of drivers in addition to the regular "physics" involved in a tractor raring up.

 

[mars1952]

Hmm..I'd like to see a pic of the mx5.. does it not have rigid connections to support the a-frame?

I will definitely post pictures of my MX5 ASAP. The upper linkage on mine is rusty where it bent. I hammered it back enough to make it useable. In the mean time here is a picture of an MX5
As you can see from the picture the MX5 is pretty robust where the lower 3PH arms attach. The part that bent is the upper linkage. It seems unlikely that I could rear rollover with this mower on flat ground. The Lower 3PH linkage would stop the rollover. Uphill is a different story. In my stroy mention in my first post. The mower stood up almost 90 degrees perpendicular to the tractor. If I was rolling backwards down a hill I don't see how the MX5 mower would have stopped me.

Also.. with a long implement on back. the tractor should not be able to reach a very high angle ( fronts off the ground ).. thus the implement doesn't have to suppor the weight of the tractor yet.. just resist traction forces...

"just resist traction forces..." what does this mean?

IE a 5' long mower ou the back should bottom out with the tractor at less than breakover point..

The implement could be 100' long. It wouldn't matter how long it was if the linkage crushed.

You bring up lots of 'ifs' if this.. if that. well sure.. IF you cahinn your tractor to an imovable object, and IF you have a wimpy implement on back, and IF you have no rops, then you will PROBABLY be mashed between that nice falt implement and your tractor IF you roll her over backwards. That's not a failure of anything but the operator... IMHO

Many people can not afford (or at least think they can't afford) to add a ROPS or buy a new ROPS equipped tractor or heavy duty implements. These are the people we need to educate. Immovable objects are often hidden, like stumps or rocks. Sometimes you don't know if an object is immovable until you try to move it. If you tell some one that all they have to do to keep from having a rear rollover is keep a 3PH implement on their tractor you are doing them a disservice. Any argument that says "Always, Never or every time" can be disproved by a single example. The reverse is not true. (I suppose that there is a counter to this rule as well.)

RANT(paraphrased)

Let's please not get ridiculous.
Marshall

 

[Soundguy]

The pto may or may not hold.. just depends on if the A-frame folds. I'd hate to se the implement and tractor after that though..

I've had to rebuild a JD pto section 2x due to a pto shaft that was toolong, and got shoved into the back of the tractor.. still.. it should do 'something' anyway..

Soundguy

"As to the bushog value against rollover - Even tho they have the top flex link, or sometimes a chain that would thwart application of compressive forces entirely, you still get earlyearly warning and a good rollback pause from that way back tailwheel touching."

One other thing...that driven PTO shaft is only going to collapse so much and would (in my limited reasoning skills) impede a full roll over even with chain used for the top link (or, in my experience, a disconnected top link).

Of course, even if the implement prevents a full roll, you'll probably be killed by being impaled by the implement's 3PH framework.

 

[Soundguy]

That looks like a decent mower...

I will definitely post pictures of my MX5 ASAP. The upper linkage on mine is rusty where it bent. I hammered it back enough to make it useable. In the mean time here is a picture of an
As you can see from the picture the MX5 is pretty robust where the lower 3PH arms attach. The part that bent is the upper linkage. It seems unlikely that I could rear rollover with this mower on flat ground.

That was the point I was making.

The Lower 3PH linkage would stop the rollover. Uphill is a different story. In my stroy mention in my first post. The mower stood up almost 90 degrees perpendicular to the tractor. If I was rolling backwards down a hill I don't see how the MX5 mower would have stopped me.

Going up a hill would certaitly be an aggravating factor. No disagreement there.

"just resist traction forces..." what does this mean?

Verbatium.. ecaxtly what is said. On flat land, if you tip the tractor back untill the mower is grounded and 3pt lift arms have traveled their max range.. then the front of the tractor will likelyy not be at a point of no return.. In other words.. if you jacked upt he front of the tractor as I just mentioned, and then let it go.. it would not continue going back.. it would slam the fronts down. In that situation.. the only forces the rear iplement would have to be able to overcome is the traction forces of the tires spinning on the ground. Aggravating factors like uneven traction or slopes will certaintly effect this.

The implement could be 100' long. It wouldn't matter how long it was if the linkage crushed.

True.. that's why i added a prefacing statement a few messages back detailing that the more stout/beefy the rear implement was.. the more 'help' it would be in 'helping' to stall a backflip.. ( not preventing a backflip ).

Many people can not afford (or at least think they can't afford) to add a ROPS or buy a new ROPS equipped tractor or heavy duty implements. These are the people we need to educate. Immovable objects are often hidden, like stumps or rocks.

I agree... yet.. this info changes -nothing- in the discussion with reference to an implement on the rear possibly helping stall a backflip. The presence or lack of a rops does not figure into the equation if you are looking intot he situation of whether or not a rear implement may help stall a backflip. Kinda like saying you have a unbreakable 4' chain on the front axle that is pinned to an imoveable object, and then you are trying to see if the implement on the rear will help stop the backflip.. makes no difference if the chain or rops will stop it.. we are just looking at the implement side of the equation.. lets keep it all in perspective here.

Sometimes you don't know if an object is immovable until you try to move it.

True.. and sometimes a cigar is a cigar. I see lots of broken tractor due to someone trying to move something they had to know was way way to much of a load. That doesn't diminish the fact that there are also probably many out there that thought they were moving less of a load.. or the load became dynamic and got out of control.. etc.

If you tell some one that all they have to do to keep from having a rear rollover is keep a 3PH implement on their tractor you are doing them a disservice.

Hmm.. I just skimmed over all the posts here.. and that text doesn't appear anywhere ( but in your post ) IE.. i don't see anyone here saying that an implement onthe rear = NO chance of a rear flip. if I missed the post that said that.. then I appologize. So far the posts i see dealing with an implement backflip are mainly geared around 'helping' to prevent or stall a backflip.

Any argument that says "Always, Never or every time" can be disproved by a single example. The reverse is not true. (I suppose that there is a counter to this rule as well.)

I agree.

Let's please not get ridiculous.
Marshall

Too late. This type of post is virtually meant to or guaranteed to ilicit heated debate. To think otherwise is sheer folley.. (grin).

Soundguy

 

[N80]

Here is the way the link on the JD LX series mowers looks:

As you can see, it flexes to a point (really nice design in terms of practical use) and then stops. At that point the stress is on the straps.

In any case, as for Myth #1, I have no technical wisdom, but it seems a bit irrelevant. In regard to preventing rear rollover, is there a better place to hitch to than the drawbar? I guess the relevance of the myth is primarily for those who think it is impossible to roll it over that way. But I'm not sure that sort can be helped with facts and figures anyway.

 

[RoyJackson]

"In regard to preventing rear rollover, is there a better place to hitch to than the drawbar? "

Well, the draw bar is designed for towing and it is below the rear axle. So, using the draw bar and some common sense is probably your safest and least detrimental to the equipment.
That, and proper use of the ROPS (including the seatbelt) will reduce, but not eliminate, the potential for an accident.

Another method of skidding, and I don't recommend this (although I did it once) is rigging the chain to bucket hooks and reversing the load to where you want it. The reason I don't recommend this is the potential for damage to your tractor's drive train. There have been at least two 790 owners who posted reports of damage to the front axle components which required replacement of some of the gears.
The gears are designed (so the posts went) to take the maximum load going forward. Reversing put stress on the gears that they weren't designed to take.

 

[Tom_Veatch]

Larry - I am with you on this, because it makes no sense to me either. The dashed line doesn't represent any real force that I can imagine. I wonder what the author was thinking?

Tom

Later Edit: I just emailed the author. I'll let you know if I hear from him.

From reading the commentary in the article, I believe the dashed line in Fig 5 is intended to be a generic representation of the "angle of pull" or line of action of the pull force. It certainly doesn't represent any actual line of force in the figure. Be interesting to see the author's response.

I find the comment in the section "Drawbar Leverage" beside Fig 5" (emphasis added)

Assumptions for this example include a tree stump that does not budge, a log chain that does not break, and a tractor with properly ball sted (weighted) tires and an engine that does not stall.

to be misleading in the discussion of rear turnover.

The only effect of weighted rear tires in a rear turnover would be to make a turnover more likely. Weighted tires have no more influence in resisting a rear turnover than non-weighted tires. The weight of the rear tires, wheels, axles, etc. provides no restoring moment in this situation. However, weighting the rear tires does enable the tractor to develop more traction. All other things being equal, this increases the ability of the tractor to lift it's front wheels before the tires break traction and begin to slip.