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Positive Pressure for axles/tranny's etc.

Discussion in 'The Garage' started by hawkeye649, Jul 16, 2006.

  1. hawkeye649

    hawkeye649 1/2 ton status

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    Anyone know how these work in particular? Are they run off of an on-board air system by the engine, electric? I was wondering what kind of PSI/volume an AIR pump (you know those useless smog things) put out, and if they could work for 2 axles, a t-case/tranny, and possibly a dizzy? hmm... :dunno:
     
  2. sled_dog

    sled_dog 1 ton status

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    positive pressure for axles? I'm sorry I'm unfamiliar with the concept.
     
  3. hawkeye649

    hawkeye649 1/2 ton status

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    Ya it's something the military does for their parts. It helps insure that water wont get into your axles. Even with breathers above the water line apparently the pressure of the water can be enough to get into your pumpkins. I'll probably never need it but it sounds cool, relatively cheap, and I have my mind set on it so I've been looking into it. :D
    My only concern is that it may force warm fluid into my lines, possibly plugging them...? :confused:
     
  4. hack500

    hack500 1/2 ton status

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    it'd work for keeping most of the mud/water out but it would also push out the gear lube, too.
     
  5. sled_dog

    sled_dog 1 ton status

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    yeah I forsee a lot of leaks. it would have to be very low pressure I'd say. What front axle do you have? MAD4wd has external axle seals for Dana 60s now, I'm personally planning to get a set to aid in water intrusion protection.
     
  6. JEBSR

    JEBSR 1/2 ton status

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    I really don't understand this concept considering vents were originally put in diffs to keep it from building pressure and blowing the seals. Can someone explain?
     
  7. hawkeye649

    hawkeye649 1/2 ton status

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    Right now it's a couple of 10b corps. I would also assume it would need to be low pressure too. I can't really imagine smog pumps putting out much at all, lest they would be super chargers.. :grin: I had even thought of an aquarium air pump, besides the 110VAC aspect they seem well equipped. They are 100% duty cycle, designed to work with resistance to the pumpage (12"+ of water above them) and are small. Maybe even one of those cheapie tire pumps with no air tank and a piston the size of your fanger would do, they wouldn't be pushing all that hard so the non-100% duty cycle might be OK.
    But when the hypoid gets warm I'm sure it slops all over the place, which probably means back into the tubes, when being forced out by air. I want to vent mine up to either the air cleaner or to the top of my snorkle so I'm worried about pluggage. I was thinking a piece of 1/2" copper tube as "hard line" for front/rear with flex lines going to it would probably carry enough volume that even if the fluid did get all up in there, that air could still pass by as it pooled in the lower half of the tube.
    I haven't been able to find much on the military apps exact workings. I was wondering if they were positive pressure, and had a short exit tube with water check valve. During normal operations the air is pumped in, and then out, and when the water closes the valve the axle is going to be cooling off and the air shrinkage will be supplimented by the pump. Only problem there is which will leak first, oil seals or check valve, to let the building PSI out? Hmm.... :dunno:
     
  8. hawkeye649

    hawkeye649 1/2 ton status

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    So no one has experience with these? :eek1:
     
  9. ntsqd

    ntsqd 1/2 ton status

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    At max my guess is that you'd need 5 psi to offset any pressure head from submergence depth. If you need more than 5, you likely also need some Scuba gear. :haha: :haha:

    If you have OBA then you could set up a regulator to hold that pressure. I would consider a system with a 2 way solenoid valve. In the "off" position the solenoid valve allows venting to atmosphere. In the "on" position the valve allows that <5 psi into the system.

    Whether the seals would hold the pressure depends on both their design and their orientation to the pressure. Remember that the seals used in axles aren't designed specifically just for axles. They're also used in other places, i.e the front crank seal of a 22R/RE yoter engine has the oil pump right behind it so it's holding back engine oil pressure.
     
  10. hawkeye649

    hawkeye649 1/2 ton status

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    Well 10 feet of water would be about 4.3 psi, so I don't think I'd need much either.

    No ex-military mechanics that know how these suckers work?
     

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