Tractor flip overs and wheelie bars

[flusher]

Reading through the threads in this forum, I noticed several discussions of flip over accidents while people were pulling things (stumps, other vehicles, etc) with their tractors. Almost invariably there was no ROPS on the tractor.

IIRC, a ROPS is supposed to provide protection both for roll overs and for flip overs. Is this correct?

What about using wheelie bars on a tractor when pulling. I know that they are pretty much manditory in tractor pulling contests. Is there anyone out there manufacturing wheelie bars for tractors?

 

[Boomerang1]

Flip overs could be avoided using the correct procedure when pulling.

 

[Soundguy]

Many 3pt implements will= a wheelie bar. For instance.. a box blade ont he back of your tractor should stall a tractor powered backflip pretty quickly before a high angle is reached..

Soundguy

 

[JC-jetro]

I'll always pull with the 3 pt carry all attached and lowered about 8" above ground. Same effect as box blade like soundguy commented.

 

[flusher]

Many 3pt implements will= a wheelie bar. For instance.. a box blade ont he back of your tractor should stall a tractor powered backflip pretty quickly before a high angle is reached..

Soundguy

Very true.

I was thinking more of the pulling situation (e.g. drag disk).

 

[MossRoad]

An implement on the 3pt won't act like a wheelie bar because the 3pt hitch doesn't have "power down". Therefore, an implement is free to float up, which is what will happen in a rear roll over.

The safest way to pull something is to use the swinging draw bar located under the centerline of the rear axle.

 

[Soundguy]

Moss... please.. look at the physics involved in a tractor 3pt hitch.

Put a ( arguments sake ) a box blade on a tractor 3pt. Now.. lift it to max.. it is going to be about 3 feet off the ground... That implement is about an inch away from max lift.. in other words.. if you grabbe dthe implement and lifted it.. it might go another inch up past what the lift piston will do... then what happens.. it stops... solidly.. it is that stopping point that the backflip would be stalled. Even on a short implement like a box blade.. measure from the rear tire contact patch, to the rear edge of the implement.. Now.. imagint a right triangle.. the rear tire contact patch and the implement contact point are on the grount. Draw a line straight up from the rear tire contact patch, and then make the hypotenuse from the implement contact point. That is the max angle the tractor can flip backwards. True, the front wheel may be 3' off the ground.. but.. the flip is still stalled. Now, iIf it were a longer implement.. say.. a 4' or 5' mower.. then you have dramatically changed ( lowered that angle).. I doubt whether the average sized cut could get more than a couple feet off the ground, depending on how their mower toplink was set.

If you read a ford owners manual.. this is stated, and listed as a 'safety device '.. for the exact reason i just stated... the correctly attached 3 pt implement will help stall a backflip. ( same as a rops.. except the implement just stops it sooner. It's all geometry...

All bets are off with a drag implement.. and if you use a 2pt hookup.

PS.. Moss.. for what you wrote to be correct, the 3pt lift arms would have to be able to rotate all the way around the tractor.. and we know that isn't happening. 3pt lift specs, ( height and width ) per tractor category are standardized, and spelled out in ASAE documents... tractor manufacturers and implement manufacturers use these when designing the 3pt lift and implements, so that the geometry works. etc.

If you can't picture this.. go borrow a CUT put a bb on it, lift it to max, chain the front down with a 6' emergency chain now use a hi lift jack and jack the front up till the box blade touches. That's you max backflip without the structure of the implement or the toplink failing. I doubt the tires can pull enough traction to do either unless we have a real wimpy implement.. like a cat 0 implement on a cat 1 tractor.. etc.

This works even better on larger tractors... On my NH 7610s.. i have a 10' mower.. at max 3pt lift, she is less than 3' off the ground inthe rear.. pivot that back.. see where the front tires go.. and stop....

Soundguy

 

[psdx]

Flip overs could be avoided using the correct procedure when pulling.

Agreed - as long as the point of attachment is BELOW the centerline of the rear axle the tractor will never flip back from pulling a load. The factory drawbar is the BEST place to pull a heavy load - a clevis mounted on the drawbar works wonderfully.

 

[flusher]

Moss... please.. look at the physics involved in a tractor 3pt hitch.


Soundguy

Agreed.

How about a double-bottom plow mounted on the 3pt and draft control. Does your analysis apply to this situation?

I ask because there's a thread going on now in the Attachments forum that warns of flip overs using such a plow and an older tractors (1960s vintage I suppose).


http://www.tractorbynet.com/forums/attachments/94592-first-time-plow-user-questions.html#post1073074

 

[MossRoad]

The discussion is pulling something with a tractor and using a 3pt implement as a wheelie bar instead of attaching the chain to the proper point lower than the centerline of the rear axle.

3pt hitches do not have "power down". If they did, we could raise the rear end of the tractor up off the ground by lowering the 3pt hitch. There is nothing holding the implement down but gravity. Yes, there is a maximum upward travel to the 3 pt arms. However, that travel is much farther than most of us realize. Let's try it.

Hook up a box blade to a 3pt hitch. Back up to an unmovable stump. Drop the box blade to within one inch of the ground. Hook a chain to the stump and run it over or under the box blade. Doesn't matter. Hook it to a point on the rear of the tractor higher than the centerline of the axle. Rev up the tractor and take off. As soon as the chain tightens and the tires grip, the front of the tractor will launch skyward because there is nothing holding the box blade down. The tractor will rotate until the maximum travel of the 3pt arms is reached. My guess is the tractor will be at an angle greater than 45 degrees in less that 1/2 second. I base this on what I have read on several reports on tractor roll overs and most agree that it only takes 3/4 of a second to go completely vertical. At that point, most operators will be in "poop your pants" mode. Not many folks (myself included) would have the skills to quickly react properly at that angle. Maybe the implement will keep it from going over the rest of the way. Maybe the top link will snap or bend and over you go.

The point is, pulling should be done by attaching to the proper place below the centerline of the rear axle always. No exceptions. If we hook up properly, we won't need wheelie bars.