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why not a hydrostatic transmission?

Discussion in 'HardCore Corner' started by Jetboy, Oct 27, 2004.

  1. Jetboy

    Jetboy New Member

    Messages:
    1,118
    This might seem like a stupid question and maybe it is not allowed in rockcrawling comps, but why don't we see hydrostatic transmissions? seems like they would give much better low end torque and more controll than any automatic. the one in our tractor is sweet for going real slow. I know they are heavy, but so is a tranny and a tcase. so it seems like with the cash that everyone is spending for their crawlers that only see the trails you could even mount a motor on each axle and eliminate drivetrain worries. Maybe I just have too much time on my hands???
  2. Niner

    Niner SILVER Star

    Messages:
    819
    Location:
    Readfield, WI
    There are other issues associated with the option you are speaking of.

    break a line off and the fitting is stuck in the hydraulic motor would be one heck of a pain on the trail, since you couldn't move until it was fixed.

    breaking an axle shaft you can still move, in most situations.
  3. Jetboy

    Jetboy New Member

    Messages:
    1,118
    yoru right there are some issues to overcome, but you could just carry some spare parts and some tools to fix the lines, also you could make a universal line that could repalce any of the lines, also the one axle could be disconected and use the other axle. you could also build protection for the connectors. It would also be easier to swap a hydrolic motor on the trail than a boroken tcase or a broken tranny.
  4. woody

    woody it's all my fault Staff Member

    Messages:
    9,614
    Location:
    Wisconsin
    if you've watched comps, it's not as much crawling as pure momentum and speed....not sure hydrostatic would provide the instantaneous wheelspin that a healthy vortec provides...
  5. Jetboy

    Jetboy New Member

    Messages:
    1,118
    I'm not sure about that I don't know how fast they react, but it seems pretty easy to do a wheelie in a bobcat. the way that our tractor works is you have a foot pedal that rocks to go foreward or reverse with no gear shifting (I guess thats a given or it wouldn't be a true hydrostatic) and in the middle is not nuetral but more like brakes, the hydro lines are locked. and as you move the throttle is automatic depending on the power needed,it sits at idle untill the system senses the need for more energy then it reacts, but it is very fast as if it is instant like stepping on the gas, but your really dictating tire speed not power applied the engine so it is more controllable power. I think part of the problem would be that you may be limited on the top wheel speeds.But that would all depend ont he ratios of pump volume, pressure and motor volume and gearing.
  6. Jetboy

    Jetboy New Member

    Messages:
    1,118
    The advantage to a clutched system is that you can store up energy in th flywheel, but most run auto's so that doesn't apply as much. and yes the torque converter with a high stall will allow it as well as a tranny brake, but I'm not sure what they are using. I have never been to a comp. I live in MT and we don't have much for rock crawling, but I'm planning to move to the SLC area for grad school next summer or fall so I would like to get a crawler started if I can find some time.
  7. heavytlc

    heavytlc Regular Member

    Messages:
    67
    The rules have stated that it had to be of automotive origin, but I know that is not always the case. Mr. Torbet does a good job with regular tractor axles, but not hydro wheel motors, or hydro static. I guess it could be legal for comp then. Woody is right on the wheel speed, at least for comps.

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