2WD design thoughts

Discussion in 'Hacks' started by XL-erate, Nov 26, 2012.

  1. bk brkr baker

    bk brkr baker Long timer

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    Pretty heavy in the weight department. My Vermeer baler has a slip clutch that uses diaphram springs instead of coils. It's heavy too,maybe there is a really small one somewhere.
    I'm not sure how this kind of slip clutch would work to allow the difference in wheel speeds in turning.
    They are used in ag equipment to prevent catastrophic distruction when your mower or baler eats a tree limb or breaks a chain.

    When Murph built his 2 wheel drive he used a semi-viscous clutch from an awd auto. They are small and probably lighter than the spring clutches.
    #81
  2. FlySniper

    FlySniper Bleh...

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    Ah heck, I'm not against it, but it would make for a really odd read down the road. (Still, it might be better....<label for="rb_iconid_28">[​IMG]</label>) I just got home from work, so I'm a little too shagged for decision making. Either way really, I made an ass of myself and can't really bury that fact.
    #82
  3. XL-erate

    XL-erate Been here awhile

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    Well that makes me want to delete some stuff even more. Just as well as there's no hard feelings it's also nice to be able to go back and give some rewrite to the gnarly stuff, lots I can remove at no loss to anyone! I'll see what I can clean up or something because there's still a whole bunch of other posts in the thread. I'll give it a try and see what can be changed or removed.

    Okay, I went back and chopped out a whole bunch of unpleasant stuff and nuked a couple of my posts. I hope it's not a problem for anyone but I figured at this point, nothing to lose and maybe it will be a little more pleasant to read this way.
    #83
  4. XL-erate

    XL-erate Been here awhile

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    I read your post at the link. I see the similarity of a shaft and a clutch drive system.

    A sprag clutch is much more mechanically complex and from what I've seen, manufacturer specific for repair, replacement or replacement parts. I think the increased complexity makes it much more prone to eventual failure, more moving parts etc. In a type that can handle 90-100 HP I believe it would be much more expensive than a steel hub/plate and a friction hub/plate. A sprag clutch is not something you can build yourself without a fairly complete machine shop and some extreme skills. Other than mentioning the shaft and sprag clutch I didn't see too much in details of build.

    As I've mentioned I haven't said that my design is the original clutch type drive or Limited Slip system, that's nothing new at all. What's different is the extremely simple design to accomplish that goal, and the DIY of building all at home except for axle splines. 2 hub/plates, 2 pieces of shaft, a few bearings and supports, sprockets & chain - done.
    #84
  5. windmill

    windmill Long timer

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    The Gravely L series tractors used a slip clutch like that, they are approximately 4" in diameter and about 2"thick. They were attached to all power implements and were in production for about 65 years so they are easy to find.
    #85
  6. FlySniper

    FlySniper Bleh...

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    Smells better already!:freaky

    On those slip clutches for tractors... Those were the first things that came to my mind, but I've not seen any as small as 4" dia.. Even that small, it seems like a bunch of rotating mass that would need supporting. I'm just not sold on the idea that they would function reliably as an LSD. But I do tend to overthink things.
    #86
  7. XL-erate

    XL-erate Been here awhile

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    Agreed on the rotating mass, also there's the overall weight, whether that would be a factor? Most tractor stuff isn't famous for being ultra-light.

    It would be nice to know if it's possible to adjust the friction rate or slip pressure. I suppose a guy could swap out the springs but it would be nice if they were adjustable, springs could get pricey with trial and error. Might be worth looking into...

    .
    #87
  8. windmill

    windmill Long timer

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    Here's a Gravely slip clutch, dont have one loose to weigh, but I would guess it is under 4 lbs.

    [​IMG]

    [​IMG]
    #88
  9. XL-erate

    XL-erate Been here awhile

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    Pretty darned compact!
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  10. Biebs

    Biebs BMW Airhead

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    Is that a centrifical clutch as speed picks up it engages?? Gravely slip cluth or did you mean Gravity??:freaky
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  11. windmill

    windmill Long timer

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    "Gravely" is a commerical mower manufacturer that made 2 wheel tractors, and all their power attachments had a slip clutch to protect the gear driven pto.

    [​IMG]

    [​IMG]

    [​IMG]
    #91
  12. XL-erate

    XL-erate Been here awhile

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    Apparently the Gravely slip clutch is rated for 30-35 lbs slip pressure.

    http://www.ytmag.com/cgi-bin/viewit.cgi?bd=ttalk&th=74365%3E

    http://www.mytractorforum.com/showthread.php?t=32659

    A Yahoo Search for PTO Slip Clutch shows there's all kinds of these things out there, might have some real possibilities. Many are electric. A guy could set one up to run 1WD 99% of the time, then if the going gets rough flip a switch and have electric slip clutch engage 2WD.

    The low horsepower part might not be a problem at all if the second drive wheel is just used as a helper to keep things rolling in soft stuff. They're probably used for many horsepower rating. I'm going to look into this a lot deeper, may be a very good solution!
    #92
  13. XL-erate

    XL-erate Been here awhile

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    I was starting to get excited about the electromagnetic slip clutches but then reality kicked in. They present the same old problems I wanted to avoid: expensive, complicated, heavy, mfr. only specialty parts, can't repair out in the world if at all.

    On the non-electric slip clutch models I saw most had very low input power ratings, like for small garden tractor engines/drives. When sizing one would have to consider engine's torque rating plus the multiplication factor of transmission and final drive ratios.
    #93
  14. FlySniper

    FlySniper Bleh...

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    Weeelll now....


    Looking at the "teeth" on the Gravely, it looks like it only works in one direction. I imagine the matching part also has the saw tooth cut.... err, I guess when enough torque is applied the teeth ride up on each other and force the clutch to open, tightening the bolts increased spring pressure to resist opening the clutch...

    So if the wheel driven by this unit (hack wheel) has traction and the tug wheel doesn't, this might actually work against you if the spring pressure is set too low. (Cutting power to the high traction side.)

    And since there is no way to disconnect power to the tug wheel alone, sharp right hand turns are still going to pit your turning efforts against a locked differential, while left turns should allow the Gravely to work. (This is where I start wondering about consistency, I don't see it performing the same in mud as it does on hardpack... it's too dependant on the spring pressure, although maybe there's a happy medium??)


    Uhg... I need to go look at one again. It's been years since I've been near a tractor.

    But... I do have something similar out in my shed. Instead of having the saw tooth shaped teeth they are triangular, so will slip in either direction. Not sure what it came from, but it's only about 2" in diameter with a 3/4" shaft.
    #94
  15. windmill

    windmill Long timer

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    The "teeth" have nothing to do with the function of the clutch, they serve to aline the drive cog on the pto. For the OP's application, it would probably work best to remove them and weld a universal yoke in their place.
    #95
  16. FlySniper

    FlySniper Bleh...

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    I found an exploded view... Not as fancy as I was thinking...:evil
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  17. brstar

    brstar Been here awhile

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