Mowing Gyro action -- an aid to hillside mowing?

   / Gyro action -- an aid to hillside mowing? #1  

MikeOConnor

Silver Member
Joined
Dec 16, 2002
Messages
170
Location
Western Wisconsin
Tractor
Two Power-Trac 1850s (preferred for mowing and grapple-bucket clearing type work on really steep hills). Kubota M680 for snowblowing, grading, bucket.
Hi gang,

This is my first post (usual story, 'been lurking for a long time, very helpful discussions, etc.).

I looked for this before I posted, so apologies if I missed it. But here's a brain teaser. I am wondering how much stability on a hill the gyroscopic action of a rotory (or flail) mower provides.

Seems t'me that I routinely mow on hills that are steeper than the 20-degree consensus (questions about sanity can be posted directly rather than to this thread). The tractor will sometimes want to **slide** down the hill, but never wants to roll.

I'm concocting the theory that this is because I'm dragging a pretty darn heavy gyroscope behind me, and it's resisting the roll motion, but not the slide motion. From there, my college physics memory fails me...

Here are the brain-teaser questions;

1) Is this right?

2) How does a person figure out how many "more degrees" they can add to the tilt meter?

Have at it!

m
 
   / Gyro action -- an aid to hillside mowing? #2  
Mike,

Welcome to TBN! Wow, for a first post, you sure picked a heck of a topic!

Well, I'm an electrical engineer and only have the fundamental understandings of the forces involved from the gyroscopic phenomenon. It sounds plausible.

However, I would hate to rely on those forces. I'd hate to see the tractor roll over simply 'cause you stepped on the clutch when something jumped in front of the tractor, or you reduced the throttle for some reason.

Perhaps those more mechanically minded will elaborate.

Again, welcome to the board.

~Rick
 
   / Gyro action -- an aid to hillside mowing?
  • Thread Starter
#3  
Hi Rick,


Nice t'be here. Thanks for the welcome...

Yep, I agree -- you wouldn't want to push it just because of the flywheel effect. But at the same time, pushing in the clutch isn't going to instantly remove the benefit of the gyro either because the mower will freewheel (my flail mower takes about 30 seconds to spin down from full speed).

One of the things that interests me is the difference between driving on the hills with the (rigidly-attached) mower vs going on the same hill with stuff that's just being pulled at the drawbar. My theory is that you should be more conservative when doing drawbar stuff -- 'cause even if you have a flywheel, it's not going to transmit the benefit to the tractor through the 3-point.
 
   / Gyro action -- an aid to hillside mowing? #4  
While we're nitpicking here, let's not forget to add in the suction effect of the blades sucking the cutter to the ground. /w3tcompact/icons/laugh.gif
 
   / Gyro action -- an aid to hillside mowing? #5  
Glad to have you join us, Mike. I think your theories are good, but I don't think I'd want to be the one to test the practical application./w3tcompact/icons/laugh.gif I hadn't thought about it before and sure don't know, but do think it should make some difference, but doubt it would be enough to be considered a benefit.
 
   / Gyro action -- an aid to hillside mowing? #6  
I doubt that the gyro effect is enough to give you half a degree, however, the fact that that heavy mower is way below and to the rear of those back tires gets the center of gravity a bit lower.
I do a lot of mowing in very steep terrain and I've been to the edge many times. With the mower on the ground I've had that lifting feeling and just lifting the mower a couple of inches gives me a chance to get the front end started downhill to get stabilized.
Be careful, if you do have a tilt meter or your backside tells you you are close, don't take any chances. It only takes a small rock or chunk lurking in the grass to tip you.
 
   / Gyro action -- an aid to hillside mowing? #7  
One other thing Mike. If you do a lot of side hill, get those back tires as wide as your rims will allow. And yes, thanks for coming on board. I'm new in here too. Sure is a lot of good information traded in here.
 
   / Gyro action -- an aid to hillside mowing? #8  
Well, I thought I'e enlighten everyone with a calculation of just what the effect of a rotating mower would have. So I went out and did a Google search for "Gyroscopic Effect" and here's what I came up with:

47-217518-gyroscope.jpg

Feel enlightened? /w3tcompact/icons/clever.gif /w3tcompact/icons/laugh.gif
 

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   / Gyro action -- an aid to hillside mowing? #9  
MikeOConnor - "The tractor will sometimes want to **slide** down the hill"

I wouldn't want to be on a hill that I'm sliding sideways on! Even if the gyro effect did help, you still run the risk of sliding sideways and then hitting a stump or rock. Once that happens the momentum of the tractor sliding sideways will cause it to flip.
 
   / Gyro action -- an aid to hillside mowing? #10  
Bill,

You're bringing back bad memories of my dynamics class! It's after noon and its still too early on a Monday to be doing that math!

If the tractor is side slipping, I wouldn't want to be on that slope!
 
 
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