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  1. #1
    Silver Member MikeOConnor's Avatar
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    Dec 2002
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    Western Wisconsin
    Tractor
    Kubota M6800, Power-Trac 1850 (preferred for most jobs)

    Default Gyro action -- an aid to hillside mowing?

    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


  2. #2
    Platinum Member
    Join Date
    Apr 2000
    Posts
    762
    Location
    Greater Springfield area, Massachusetts
    Tractor
    Kubota B2910, also Honda HT3813 with mower and front blade.

    Default Re: Gyro action -- an aid to hillside mowing?

    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

  3. #3
    Silver Member MikeOConnor's Avatar
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    Dec 2002
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    124
    Location
    Western Wisconsin
    Tractor
    Kubota M6800, Power-Trac 1850 (preferred for most jobs)

    Default Re: Gyro action -- an aid to hillside mowing?

    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.

  4. #4

    Join Date
    May 2002
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    579
    Location
    Harrisburg, Illinois
    Tractor
    MF 165, Kioti 2554

    Default Re: Gyro action -- an aid to hillside mowing?

    While we're nitpicking here, let's not forget to add in the suction effect of the blades sucking the cutter to the ground. [img]/w3tcompact/icons/laugh.gif[/img]

  5. #5
    Epic Contributor Bird's Avatar
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    Mar 2000
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    37,308
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    Texas

    Default Re: Gyro action -- an aid to hillside mowing?

    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.[img]/w3tcompact/icons/laugh.gif[/img] 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.

  6. #6
    Veteran Member
    Join Date
    Dec 2002
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    1,070
    Location
    Western Washington
    Tractor
    5300 JD 4X4

    Default Re: Gyro action -- an aid to hillside mowing?

    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.

  7. #7
    Veteran Member
    Join Date
    Dec 2002
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    1,070
    Location
    Western Washington
    Tractor
    5300 JD 4X4

    Default Re: Gyro action -- an aid to hillside mowing?

    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.

  8. #8
    Veteran Member
    Join Date
    Jul 2000
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    1,344
    Location
    West Virginia (Eastern Panhandle)
    Tractor
    '78 Kubota B6100DT

    Default Re: Gyro action -- an aid to hillside mowing?

    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:


    Feel enlightened? [img]/w3tcompact/icons/clever.gif[/img] [img]/w3tcompact/icons/laugh.gif[/img]
    Attached Images Attached Images

  9. #9
    Veteran Member
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    Jan 2002
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    Location
    Colorado
    Tractor
    2000 New Holland TC29D with 7308 FEL, and top & tilt. 1950 John Deere B. 1940 Farmall A.

    Default Re: Gyro action -- an aid to hillside mowing?

    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.

  10. #10
    Elite Member hazmat's Avatar
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    Feb 2002
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    West Newbury, MA & Harrison, ME
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    Kubota B3030 loaded!

    Default Re: Gyro action -- an aid to hillside mowing?

    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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