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  • Boostinjdm
    replied
    Originally posted by Doc Nickel
    Russ-
    Question though- what do you mean by "opposing" seals? I was given to understand a lip seal worked best when there's the greatest pressure differential between the two sides of the lip.

    Doc.
    Two seals like a two way hydraulic cylinder. One seal may be fine, but I would be worried about raising the handle too fast and sucking some air past the single seal. One above it facing the opposite direction would take care of that.

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  • Doc Nickel
    replied
    Russ- Yep, looks like it is BSP. Thanks for the link.
    Boost-That's my current plan, at least for the moment. The bore is 1.571", which is closer to 40mm than most of the fractional-size seals that McMaster shows (thanks Weird) so I'm trying to find a workable seal before I make the piston.

    I'll probably leave the clip there, so the piston won't be taking the strain- the threads on the end of the ram are only a bit bigger than 1/4-20. The spring's a good idea though...

    Question though- what do you mean by "opposing" seals? I was given to understand a lip seal worked best when there's the greatest pressure differential between the two sides of the lip.

    Dan- that's what I'll probably do at this point, but as I said, whoever tried to mash it in place also slightly distorted the threads of the plug. I'd have preferred to replace it if I could, but it looks like that'll likely be more trouble than it's worth.

    Doc.

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  • Jaakko Fagerlund
    replied
    BSP G or R 1/4" plugs are readily available from the plumbing section of local hardware store, unless you guys across the sea use something of your own.

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  • Lu47Dan
    replied
    Doc, I think you do need to make a new piston for the pump, just remember to allow for the added thickness of it.
    For the plug for the check valve, If the threads are not damaged past the point of use, then why not just add a new stop rod to the plug. If I read the post correctly it has a copper compression seal on it, correct? Replacing the rod would save you from cutting the Whitworth(?) threads.
    Dan.

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  • Boostinjdm
    replied
    I think I'd consider making a new piston with opposing seals. Then ditch the snap ring for a spacer and rubber washer or some type of spring. That way the stop has a little give. Something like a valve spring comes to mind as an option.

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  • RussZHC
    replied
    Bsp

    Looks to be British Standard Pipe

    http://www.oldengine.org/members/diesel/Tables/bsp1.htm

    ?, on the linked chart 1/4" and 3/8" are 19 tpi with the 1/4" being .518

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  • Doc Nickel
    replied
    Next question: The two check balls between the pump cylinders and the output to the ram are held in place with threaded plugs with a long "pin" on the end. The pin I'm presuming limits the travel of the check ball, and the plug is a straight thread with a copper washer for a seal.

    One of the two plugs has been damaged- it looks like somebody may have dropped an extra check ball in place, or one considerably oversized, and tried to tighten the plug back in place.

    This distorted the threads slightly, and actually bent the pin (which is just mild steel.)

    I was going to make a new plug, but it's an oddball thread: approximately 19 tpi, and .517" OD. It's neither a standard US thread nor a metric- at least according to my metric thread pitch gages.

    What is it? Whitworth? British Straight Pipe?

    Doc.

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  • Doc Nickel
    replied
    Originally posted by Lu47Dan
    Doc, could the snap ring be the upper travel limit of the pump?
    -It does, and that's what I'd assumed the ring was there for. My question is, that it's sustained damage from excessive force, and from the direction as if someone had, in fact, been slamming it against the upper threaded cap repeatedly and forcefully, but there is no trace of matching damage on the cap itself. No wear, no peening, no marks, nothing.

    That makes me think there was something between the cap and the snap ring, though I can't think what that might have been.

    How tight is the fit between the piston and the cylinders wall? If the pistons edges were polished and then the cylinder honed to a very close tolerance fit a HV low pressure pump would pump oil at low pressures.
    -It's pretty close, and I have no doubt it'd pump oil with reasonable efficiency. But without a seal on the piston and no seal on the upper cap, there's nothing to keep fluid from building up above the piston, and then being pumped overboard through the cap. There has to be a seal in there somewhere.

    Doc.

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  • Lu47Dan
    replied
    Doc, could the snap ring be the upper travel limit of the pump? I have had a couple of piston hand pumps apart and they either had a heavy snap ring or a reduced upper shaft diameter with a sharp shoulder as the stop.
    How tight is the fit between the piston and the cylinders wall? If the pistons edges were polished and then the cylinder honed to a very close tolerance fit a HV low pressure pump would pump oil at low pressures.
    Dan

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  • wierdscience
    replied
    You got me,that setup is a bit unusual.

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  • Doc Nickel
    replied
    One other bit: On the pump ram, there's a snap ring toward the lower end, just above the tapered portion.



    This snap ring, and it's mating groove, show signs of abuse- as if the ram had been raised to the max upward stroke, regularly and forcefully. The clip is bent slightly concave, and the groove's edge is peened slightly.

    However, the underside of the threaded cap shows no damage or wear at all. If the damage on the shaft came from being raised rapidly and forcefully, it must have hit something besides the cap.

    What that other thing could have been is beyond me, though.

    An alternate theory is that the damage came when someone tried to remove the now-missing piston. The nuts, threads and disc at the end, however, show no damage, so... ?

    Doc.

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  • wierdscience
    replied
    Originally posted by Doc Nickel
    The seller said that what he'd intended to do, but before he could, he got a good deal on a 50-ton Dake.

    It's always possible, of course, but I'd prefer the manual pump for the time being. (That and I'd rather not blow $300+ on an electric power pack at the moment. )

    Doc.
    With as big as that HV pump is,it will prbably out pace the porta power pump anyway.

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  • wierdscience
    replied
    Originally posted by Doc Nickel
    -I'm assuming the piston would go above the existing steel disc? And that it'll tighten against the taper to seal the inner bore of the piston?
    Yes,that's what I am seeing.

    Originally posted by Doc Nickel
    --So there shouldn't be any oil above the piston?
    If there isn't a seal in that cap,then there couldn't be,it would leak every stroke.


    Originally posted by Doc Nickel
    --There's check balls everywhere. I got at least five out of this thing. There's two checks between the handles, one below the handwheel, and one at the bottom of each pump. I was planning on replacing all of them, as several have rust, but that's a good idea on the lapping of the seats.

    Doc.
    The two in the pump bottoms should be inlet checks,gravity operated,the two between the handles will be outlet checks and spring loaded?And the one under the handwheel will be the return block.

    The two inlets and the return block will be the most important.

    Did you get into the cylinder yet?

    Leave a comment:


  • Doc Nickel
    replied
    The seller said that what he'd intended to do, but before he could, he got a good deal on a 50-ton Dake.

    It's always possible, of course, but I'd prefer the manual pump for the time being. (That and I'd rather not blow $300+ on an electric power pack at the moment. )

    Doc.

    Leave a comment:


  • macona
    replied
    Or you can do what I did, replace the hand pump with a port-a-power pump. Electric, that is.

    Leave a comment:

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