Improving hydraulic bottle jack

**wizard69** · Nov 21, 2017, 08:46 PM

If you guys are in need of seals for hydraulic or pneumatic cylinders, especially odd ones, try: Hydraulic cylinder repair seals and kits-Hercules Sealing Products - Hydraulic Seals and replacement cylinders for construction and many other heavy equipment industries.. Most of my rebuilding involved Parker glands and in that case we just ordered from Parker. In any event if you look around a bit you will find the raw materials for hydraulic cylinder building or rebuilding. there is a big market for custom built cylinders, often built by smaller companies, and they need to get their parts from somewhere.

As for seal replacement it is usually best to go with an exact replacement when possible on a piston. I've actually seen enough seal failures that are not wear related per say that I inspect each cylinder before considering a complete replacement. This is especially the case due to seals being subject to damage from improper installation of the piston.

Oh one more thing with respect to safety, DON'T TRUST ANY JACK, with body parts you want.

**wizard69** · Nov 21, 2017, 08:56 PM

The chat about oils is very interesting, you guys should be glad that you aren't working on hydraulics running on water/glycol. I spent a couple of years working in a die cast foundry and everything ran on water/glycol mainly due to safety concerns in event of a leak. Between the heat and the water/glycol I got really good at replacing shaft seals fast.

Now days I'm in an different industry and can count on seals holding up for years - what a relief.

**Yaculls** · Nov 23, 2017, 12:24 AM

Thanks for the post Tony.

I found it very interesting and you made a good point as to why you shouldn't put any part of your body under an object being held up by jacks.

It made me think about the guys I had replacing my stumps under my house they used a fare few bottle jacks during that operation.

**Steved53** · Apr 19, 2018, 03:53 AM

(QUOTE) It is never good practice to place any body parts under anything only supported by an hydraulic jack, and the findings here only serve to emphasize why. (QUOTE)

Or anything else supported only by hydraulics.... Or ropes... or chains... or jacks ... or etc etc. Stands or blocks every time.

**bruce.desertrat** · Aug 9, 2018, 06:57 PM

Well I knew what nhengineer meant by "a big MF pipe wrench", but google seems to think it's a combo open end/closed end wrench https://www.jensentools.com/images/p...01_s500_p1.jpg apparently because Proto has a -MF- in the model designation....

**nhengineer** · Aug 14, 2018, 11:23 AM

Most everyone knows what an "MF" is.

**nhengineer** · Dec 7, 2018, 07:48 AM

Originally Posted by tonyfoale

A while back I detailed how I upended a bottle jack for use in a press.
See here http://www.homemadetools.net/forum/i...5188#post81319

"....It would have been much easier if I had unscrewed the cylinder from the base but it resisted all my efforts to do that. I was concerned that any increased effort would distort the cylinder...."

The cylinder is really screwed tight into the base. This trick was shown to me by a old bottle jack rebuilder (my dad). With the jack base securely locked in you best, floor mounted vice, put the ram and ram cup back in, almost all the way down to the bottom. Get you BIGGEST pipe wrench and slide a long pipe down the handle. Grab the cylinder as close to the location of the ram & cup as you can. Grit you teeth and unscrew the cylinder - it will usually give without collapsing.

When you're finished with whatever you need to do with the cylinder, reinstall it using the same procedure. If you try using a bench mounted vise, you'll drag the vice and bench all over the shop unless the bench is securely floor mounted.

**69G T O** · Dec 7, 2018, 07:49 AM

Originally Posted by nhengineer

I'm curious what GOOGLE thinks a "big MF pipe wrench" is. Around here (central NH, USA) the "F" part is an expletive and the "M" part stands for mother. It looks like this Attachment 20494 only the handle is 48" long.

Here's the WEB page. https://www.whitecap.com/shop/wc/p/r...iABEgICk_D_BwE

Back 30 or so years ago I purchased my parts kits from The Jack Pack & Tool Company on N Marianna Ave, Los Angeles, CA. They are out of business - couldn't compete with $25 Chinese throwaways. Now, if it won't hold the weight, I put in a new ball check (from McMaster-Carr). The ram cup is usually not available but ram cups seldom are the problem anyway. The only other "seal" is the shaft wiper (and now-a-days that usually just a standard O-ring), the release needle valve housing and the pump ram (and they're usually just O-rings too). I've seen some jack rams with double or triple O-rings instead of a cup. That kind may NEVER give satisfactory results under max load after a bit of use and maybe not even when brand new.

Basically, if it won't hold the weight, it's the ball check and that's just a commercial steel ball bearing. If the ram cup is worn out, I trash the jack because, if it's worn out by spending its life in nice slippery hydraulic oil, it's seen a great deal of use and time to be retired. Same deal for the pump ram. The pressure is generated by the pump ram with a ball check usually on the far end of the chamber.

The gauge on my 20-ton press is maxed out at 40K psi. That's when the relief opens. Working pressure is red lined at 30K but I've occasionally loaded it up to 40K on special occasions. 8.5Kpsi should not be much of a challenge even for Chinese jack power units.

Does the ram creep back under load? That would most likely be the check valve. I'm glad to share what I know with you.

I hope I've helped somewhat. Get back to me if you need more information.

A lot of the time you can "clean up the seat" with a little TLC. The check ball is a hardened steel ball bearing and the seat is mild steel,so take a brass punch center it on top of the ball while it is on the seat and smack the punch with a big 'ol hammer.Then remove the ball and inspect if there is Any damage then trash the jack.If no damage put her back together and enjoy.

**love-horsepower** · Dec 15, 2020, 11:47 PM

You measure any seal o-ring backup washer square seal they will have it

**nhengineer** · Jan 8, 2021, 08:33 PM

Originally Posted by 69G T O

A lot of the time you can "clean up the seat" with a little TLC. The check ball is a hardened steel ball bearing and the seat is mild steel,so take a brass punch center it on top of the ball while it is on the seat and smack the punch with a big 'ol hammer.Then remove the ball and inspect if there is Any damage then trash the jack.If no damage put her back together and enjoy.

Yup, that's what I do. Works slick.