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A question about splitter pumps.

Discussion in 'Chainsaws and Power Equipment' started by metalcuttr, Jun 13, 2021.

  1. metalcuttr

    metalcuttr

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    I have a Dirty Hand Tools 35 ton splitter. It has given me trouble free service for going on 6 years. I recently split some gnarlies for an acquaintance and noticed a few drops of hyd oil on the floor under the pump when I had it parked in the garage. It has never done this before. I did have the machine stall for a few moments before continuing to split on a number of the crotches and knotty pieces. I don't think I have ever totally stalled the wedge before. I have the impression that the pump and coupler are dripping dry because it has slowed to nothing in a few days. Is this normal as a machine gets older. I am one of those guys that can't stand anything leaking even a small amount. Appreciate any comments. Thanks.
     
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  2. Eric VW

    Eric VW Moderator

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    Did you check all fasteners for tightness? You know how heat likes to make metal expand....
     
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  3. jo191145

    jo191145

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    The clear hose on my DHT hardened to glass and leaked all the time. When I finally went to replace it was when I learned how hard it had gotten. Crumbled into bits.
    If it’s on the lovejoy I don’t think it’s the hose tho. Sounds like the pump seals. Unless your 35 is configured differently than my 28
     
  4. Screwloose

    Screwloose

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    Just inside of the seal is a small hole in the bearing plate on the suction side of the pump to scavenge any oil that makes it through the bearing. The seal is not a high pressure one and a few things can cause it to weep.
    I'd wipe it off and monitor it and if it persists and gets on your nerves just replace the pump.
    Pumps are a commodity item and are typically interchangeable size for size.
    Stay away from aluminum pumps.
    Check your coupling and mounts carefully. A worn coupling can cause eccentric radial loading.
     
  5. metalcuttr

    metalcuttr

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    I went out and cleaned the pump/coupler/entire surrounding area, and then ran the splitter. When I put a load on it there is a small gush of fluid from the front of the pump area. Looks like the seal is failing. I checked the hyd fluid level and it was not appreciably low so what ever happened must have just happened. I was able to locate a direct replacement pump on Flea-bay so I went ahead and ordered it. They call for a 17.5 gpm pump and it seems that everyone else is selling 16gpm or 22gpm but nothing in between, although I did locate one 18.5. It was with in the same pressure range. I wonder if that would give greater cycle speed to the ram but maybe increase the heat in the fluid (thinking out in the future if I ever need another one). Also the coupler seems to be nice and tight with no play, cracking or damage. Probably will not replace that. Thanks for the suggestions!
     
  6. Screwloose

    Screwloose

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    I couldn't resist the urge for a autopsy when the dust settles.
     
  7. brenndatomu

    brenndatomu

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    Higher gpm takes more hp to run it...but no worries, if the small increase is even noticable, you can easily lower the pressure that the pump switches from hi flow to low flow mode at, which will keep the engine happy. I would have probably ordered that pump too...
     
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  8. metalcuttr

    metalcuttr

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    I understand exactly. I will tear down the old pump and possibly try to rebuild it if parts are available.
     
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  9. metalcuttr

    metalcuttr

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    The min HP engine for that pump was 9.5 which is what I have. I will have to go back and check the specs. Maybe the max pressure was higher.
     
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  10. Screwloose

    Screwloose

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    I definitely do not recommend rebuilding it.
    In order to do a rebuild you will need to reduce what is essentially "blow by". Most likely end plate to gear wear. You can grind the plates flat then grind the gear sides and then reduce the body again by grinding to the actual required clearance.
    It only takes a very, very small amount of wear to allow 2500+ psi of warm and thin fluid to wind up in the seal cavity.
     
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  11. MasterMech

    MasterMech The Mechanical Moderator

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    If he's only bumping it up 1-2GPM from stock - I wouldn't expect there to be any problems. When that thing unloads into "low", the difference is likely to only be .5-1 GPM and there's usually a fair amount of design "overhead" in the available engine power.

    I say - give'r!
     
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  12. MasterMech

    MasterMech The Mechanical Moderator

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    Same for some of my mechanical charges at work. Even a $5-6k vacuum pump is generally not worth re-machining.

    There are exceptions, some pumps are built with replaceable wear parts and surfaces made available in kits from the OEM. Prime examples are axial piston units found in older ZTR Mowers and their associated wheel motors. But a typical gear pump like these splitter pumps doesn't usually have such a kit available.
     
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  13. brenndatomu

    brenndatomu

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    It's typically more than that...1/4-1/3 is more common...so a 12 GPM would flow more like 3-4 GPM in high pressure/low flow mode.
    Like this one...
    Hydraulic Log Splitter Gear Pump: 2 Stage, 16 GPM
     
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  14. metalcuttr

    metalcuttr

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    Received the replacement 17.5 gpm pump and got her in. I also replaced the filter and removed and cleaned the pickup screen on the intake side of the pump. The screen seemed to have a lot of sludge in it. I wonder how well they clean the box tube/reservoir when they are fabricated or maybe fines from the failed pump? At any rate, all is clean now and reassembled. I have not filled with fluid and test run yet because I have been laying low because of this beastly heat (forecasted over 100* for today and in the 90*'s the past few days). Next stretch of more moderate weather I will hopefully wrap this project up.