Slope...What is safe V2.0.

   #1  

Evets Tsorf

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May 16, 2019
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northern California
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John Deere 750
There was a thread started a couple weeks ago posing the question,what is safe, anyone roll over? This thread went off the rails for sixteen pages, discussing the type of vegetation we mow and why, discussions of the meaning geometric equations and some reference to the Road Runner and Coyote.

In this thread I posed a question that I am still looking for an answer for.

I purchased an older John Deere 750 for a piece of property I purchased last year. It has some slopes that I would not use this tractor on. Some I do with a tight sphincter. I have a five foot brush hog that is big for this tractor, I made an assumption that as this implement being quite heavy and very low to the ground should increase the stability of the tractor. There are many stories about people rolling their tractor brush hogging, rolling tractor and wirling blades likely to tighten my life insurance underwriters sphincters too.

What am I missing on the CG of the tractor, the brush hog is lower and heavier than many ballast boxes we put on our tractors for stability.
 
   #2  

Roadworthy

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Your tractor is a bit on the small or light side for that brush hog but not unworkable. Some tractors allow the rear wheels to be moved farther apart - that would add stability. Putting ballast (liquid) into the rear wheels would also help lower center of gravity. If the tractor happens to start over be prepared to exit in a hurry. The mower may slow you down but the tractor probably weighs three times what that mower does. If you have a front loader, keep it low. The TBN store does carry a tilt meter. That may be a worthwhile investment for you.
 
   #3  

Agvg

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Norway
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Does your manual has any data on side way stability? Any picture showing the slopes?
 
   #4  

Diggin It

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Side mowing slopes is pretty much always a bad idea unless the machine is designed for it. Aside from whatever the tractor may do, that extra weight behind can start to slide down hill and pull the rear of the tractor with it. It's not just static ballast, it's whirling ballast on wheels and will react accordingly.

Mowing straight downhill with extra weight behind can push the tractor and maybe overcome limitations of the transmission and the ability of the tires to adhere to the ground.

Mowing straight uphill with that weight behind can cause the front tractor wheels to become light on the ground and lose steering.

I do my steepest hills straight up and down with a belly mower.
 
   #5  

TerryR

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Boone, NC
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JD 870
In your original post you asked what is a safe slope, uphill, downhill, and sideways. The reason you never got a satisfactory answer is that nobody knows. It depends on a lot of factors, including lots of details about your equipment, which you didn't provide.

I used an JD 870, which is one model later than your machine and one size larger, to mow my field with a 5-foot Bush Hog brand rotary cutter for over 20 years. I have the rear tires set to maximum width and all four tires loaded. My steepest slopes are 20 degrees, or 36%. I have mowed across that once, but quickly decided to mow that section up and down. The problem is, it's that steep at the top and bottom as well, where I have to turn around. I do that carefully.

I've seen suggestions from time to time about getting an incline meter. Why? That only tells you what the slope is and not how steep is safe. You can measure the slope for free with your iPhone.

You ask whether the mower makes the tractor more stable, since it's lower than a ballast box. A ballast box is used to compensate for a load on the FEL, not for hillside stability. I doubt the mower makes the machine any more stable, but it will certainly drag it sideways on a side hill. Even on my less steep sections I need to run the front tires close to a foot higher up the hill to keep the mower cutting where it should.
 
   #6  

Henro

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I think the specific question is:

Is a tractor with a brush hog attached more stable on a side slope than the tractor would be without the brush hog?

At first thought it seems like it might be, but all bets are off if the mower causes the rear wheels to break free and start sliding down slope.

My gut is telling me that a relatively large mower on a smaller tractor would make the tractor less stable on a side slope, rather than more stable...especially when the tractor is moving.

Edit: After posting I see Terry has the same conclusion in his last paragraph
 
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   #7  

flusher

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Sacramento
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Getting old. Sold the ranch. Sold the tractors. Moved back to the city.
You can increase the track width with spacers to improve stability on those slopes. And use the widest rear tires you can find.

Here's my 1964 MF135 diesel that has rears with 16" rims and 18" tread width. This tractor was lowered to work in the orchard. The front spindles were shortened to keep the tractor level.


MF135 stump2.JPG
MF135 stump1 (1).JPG

Good luck
 
   #8  

3Lfarms

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The only way I see an inclinometer being of any use would be to mount it, then pick up one rear tire with a forklift until the tractor is ready to tip over. Mark that angle on the inclinometer as the bail out point.
 
   #9  

CobyRupert

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Washington County, NY
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JD 5075E
My :2cents:
- Adding weight below the CG lowers the CG.
- When the attachment is lowered to where its weight is on the ground, it doesn't lower the CG.
- On flat ground, one can see that a raised mower will put more of the tractor and mowers total weight on the rear tires. One would say that on a sidehill, this will alter the traction and increase sliding possibility (i.e. more weight on a decreased effective tire area) depending on soil conditions, tire types, etc...

However, remember that on a sidehill, when tailwheel is slightly raised, some of the mower's weight gets applied to the top link (above the CG.). It seems to me that some of this force would be in a twisting "downhill" torque direction, promoting overturn. (Other may want to check my thoughts here.) This would be in addition to lightening front axle traction.

- I say that if the mower is lowered to were tailwheel eliminates torque on the toplink, and remaining mower weight is on lift arms below tractor's CG, CG is being lowered. While also not shifting as much weight from front axle to rear axle

This is a very dynamic situation. Another reason it doesn't make sense to depend on maximum tilt angles determined when "at rest" that are totally different than when traveling and dipping into a hole, or climbing a stump, or while turning, etc..
 

Diggin It

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Also remember that no matter how stable you feel on a slope or how many times you've worked it safely and 'even' it looks, one molehill, gopher hole or soft spot from moisture can change your angle quite suddenly and toss the machine to one side unexpectedly. I've hit hidden low spots when not on a slope that have kicked me to one side quickly.
 
 
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