20 T Bottle Jack Howzit Work? - Need To Fix!! HELPPPPP!!!

Hey!
I've got a (now old) 20T (low profile) made in Taiwan bottle jack. It doesn't want to pump under load.
I opened up the plunger assembly and found the plunger with an O ring
seal on the top end, and a cup washer on the bottom (tight fit), below which was a metal valve thingie with two ball bearings. No sign of a problem with them.
There were some tiny thin small shards of what looked like rubber hanging around the balls though...cleaned it out, anyhow. Dunno where that rubber is from. <worries about it>
(no external leaks and the reservoir is full)
Two things:
- is there a decent parts blow up anywhere on the web?? URL? - rebuild instructions anywhere on the web??
and,
- is there supposed to be a SEAL or O RING of any sort between the screw-on (hex) assembly's threads (with the plunger) and the metal valve thingie?? Or below the metal valve thingie?? <---??? <wondering how it is supposed to seal>
Seems likely to me that I'm just not getting a good seal around the metal valve thingie, and there is bypass, making for a lack of pressure...??
HELPPPP!!!
_-_-bear
PS. any reason NOT to use standard hydraulic fluid, any reason NOT to use ATF??
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I hate it when that happens........
Are you trying to repair this thing out of curiousity? If not, a new one costs about $20.
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ATP* wrote:

Try 40 bux + tax on sale at Harbor Freight... and I need to use one in the not too distant future...
Wanna try to fix it first. Low hours, driven on Sunday...
_-_-bear
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You know, if you decide to buy a new one, and happen to have a compressor, they sell a 20 ton jack driven by compressed air, for just $69.99 when they are on sale. Highly recommended!!!
i
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Ignoramus24560 wrote:

What I need is for someone to answer the Q's I had so that I can at least try to find out what has gone south on this one!! Then we'll see.
And, compressed air ain't gonna work where there is no compressed air to be had... :- (
_-_-
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BEAR wrote:

Sometimes the cheap cast iron barrel (inside the big reservoir housing) splits under load--It'll pump up-no load, but not when loaded=--If you have a lathe & brake cyl hone ,or a buddy with same, you can make a new barrel--otherwise s**t can it!--Jerry
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jerry wass wrote:

ah ha.
So, time to open up the big /nut/ on the top and see what there is to see... split? It wouldn't dare... it seems to have stopped working since the last time I used it tho'...
_-_-bear
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OK, FINE! <G>
There are only four moving parts in a bottle jack, if you ignore the screw in the ram, and the little equalizer arm on the pump.
1) the main piston. Fitted for seal in the cylinder by one or two o-rings which are sometimes let into the cylinder wall, and sometimes held in a screwed-on gland at the top.
2) the pump, usually sealed by one o-ring in the top of its cylinder.
3) bleed/check valve. Usually a simple ball-check, sometimes on a hard seat, sometimes on an o-ring seat.
4) the intake valve for the pump. This is sometimes in the bottom of the pump, and sometimes in the main cylinder base in the same bore as the check/bleed assembly.
When the intake valve is under the check valve (which is common), it can become unseated by unscrewing the bleed screw too far, then actuating the pump. Screwing the check valve back down sometimes won't restore it to its seat. The same thing can happen to the check valve.
The torn rubber may just be the sealing o-rings around the bleed screw, or they may be the seat for either the check valve or the intake valve. It's pretty easy to check.
If the cylinder goes up a tad when the pump piston is depressed, but then goes back down when the piston is raised, the problem is probably in the check valve. If you get no motion, it's probably the intake valve, or air in the galleries to the pump. If the thing is spitting oil out the pump, it's the top pump seal. If it's coming out around the ram, it's the top ram seal.
Usually the o-rings are all stock metric stuff, and there's a fair amount of "fudge" so not-so-exact rings will still work. There are at least a couple more o-rings sealing the tank to the base and the tank to the outer diameter of the cylinder
Take the jack screw or nose off the ram. Empty the oil. Unscrew the "tank" from the base. You may have to unscrew a clamping ring from the top of the cylinder to get the tank off. In that case, usually the tank is just held down by the clamp ring, and isn't threaded into the base. Some use both. Both are sealed with o-rings.
Clean up your work area again of the four or five ounces of spilled oil you thought you'd gotten out already.
The main cylinder and base will be naked and exposed for your review.
Disassemble the check/bleed assembly, using a magnet to fetch out parts, and minding their order. You can find up to two balls and three springs in some of them, and the occasional spacer.
Take the cotters out of the pump arms, and pull the pump ram straight up out of the pump.
Unscrew the cylinder from the base. Pull the ram out the bottom of the cylinder.
Clean up your work area again of the two or three ounces of spilled oil you thought you'd gotten out already.
... not much else to see, except for inspecting the base for cracks between galleries. It's made "Chinalloy" steel (actually re-melted wire hangers and Pabst cans from 1948, which is malleable on Tuesdays, Thursdays, and Saturdays, and brittle as a soda cracker on the other four days.
None of the o-ring grooves will have their edges de-burred, so torn o-rings are par for the course as you attempt to insert new ones.
Replace all rings, re-assemble in reverse.
Clean up your work area again of the one or two ounces of spilled oil you thought you'd gotten out already.
LLoyd
LLoyd
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Lloyd E. Sponenburgh wrote:

ok.
yep, bug hex on the top around the ram/piston.

seems so.

now... where would that be?? At the bottom of the pump assembly?

ok, there is a metal assembly, about the dia of a quarter, two balls in it, one on top one on the bottom, swaged in place, chambers within... below seems to be a passage (big) to the reservoir, machined out areas around the sides of this short cylinder (the thing with the balls in it)
this is the intake valve - pull back on the pump and it pulls fluid up, push down and it routes it to the cylinder??

Bleed screw being the thang that takes us -down-? hmmm... so ya think there is something in there besides a pointy seat for the screw?
then actuating the

k.
It tries to go up, usually does under no load. Absolutely makes no umph with any sort of load.
Just trying to get the idea of where the parts are and what they do... and figure out where the fluid is bypassing whatever...
...so you say they all have some valving behind the bleed screw??
Thanks for the help so far.
_-_-bear

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You lost either a cup seal or one of those o rings has shed bits and isnt sealing.
Gunner

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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I'd try bleeding it first... it just might just be the problem.
Open the release valve, be sure the ram is completely down then pump it 40 or 50 full strokes... close the release valve and see if it works.
Good Luck!
Erik

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There's a great animation here showing how a bottle jack works:
http://www.hyjacks.net/animation.htm
And the manual for the Harbor Freight version shows a parts breakdown on the last page:
http://www.harborfreight.com/manuals/93000-93999/93436.pdf
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"I'm not grown up enough to be so old!"

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On Mon, 09 Oct 2006 10:16:01 -0400, with neither quill nor qualm, BEAR

Hydraulic http://www.harborfreight.com/manuals/93000-93999/93436.pdf
Air-Over-Hydraulic http://www.harborfreight.com/manuals/41000-41999/41487.PDF

Common problems include: grit stuck in check valve or pressure relief valve, damaged pump o-ring, damaged ram seal.
------------------------------------------------------ I survived the D.C. Blizzard of 2000...from California. ---------------------------- http://www.diversify.com Comprehensive Website Development --------------------------------------------------
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