First, thanks for the replies to the earlier thread. The calcs were very
inneresting, and indeed, power calcs are really just applications of
newton's laws, F x d, and F x v, as I now see.
The Q is basically this:
Given a standard manually operated bottle jack/cylinder, is it
straighforward to add air power, or a hydraulic pump? It seems that the air
bottle jacks in the previous link I supplied, as well as one carried by HF
($79) are pretty simple, or they wouldn't be so cheap.
In fact, in those air units, you can use air or manual hydraulic operation.
I have the pumps from a car lift, and a nice 50 ton bottle jack, and it
would be nice to be able to hook those up.
Also, in this type of conversion, what are the pros/cons to using air vs a
hydraulic pump on a manual hydraulic bottle jack?
Is one better ito of fashioning a "quick return" or an automatic return
(upon hitting a stop or sumpn)?
Any DIY sites that show this, and some of the hardware req'd?
There have been discussions in RCM about modifying bottle jacks to be
operated in the upside-down position in a press frame (with a separate hand
pump), and I think someone had pointed to a website that had a parts
breakdown and pictures showing the required parts.
Trouble is, I don't have any idea how long ago that was, but a search of the
RCM archives over the last 2 years would likely bring up the discussion(s).
Since you have a power pack, you'd want to substitute the existing hand pump
piston with a fitting for pressure/fluid flow in (if the base casting is
suitable for this type of modification).
You'd also want a reliable overload bypass (already exists in nearly all
jacks), and a release valve to allow the fluid to return to the power pack
to allow the ram to return to the down position.
If the fluid can't return to the power pack, the fill plug will likely blow
out when the jack reservoir gets full, maybe.
Some jacks utilize external springs to withdraw the ram from the extended
position when released.
You shouldn't only rely upon the release valve in the power pack, because
the hose could develop a leak and drop the jack.
The overload bypass is critical, so you don't end up blowing seals, but then
your personal life is up to you.
What you choose to do in the privacy of your own shop is your business, but
hopefully you have a more rewarding, more tasteful source of income.
I put a 12 ton air/hydraulic on my arbor press last year. Its awesome, but
I need to remove the little holder clip so that it can not be locked in the
continuous position. Oops.
$79.95 from HF if I recall. My little portable compressor runs it just
fine. I also pop it out of the press and use it sometimes when I need more
than one jack on the floor. For heavier stuff like the front end of a truck
it seems to struggle a little, and I know that is nowhere near the 12 ton
claimed capacity. Front end of one of my 3/4 ton pickups is a lot lighter
than that. I have actually considered picking up a couple more of these
jacks or similar just to have them for stuff like this though. Its handy to
just hit the air instead of trying to find an angle to work the handle on my
floor jack. I've also considered an air operated floor jack.
Anyway, they are pretty affordable. If you spent the time working on
something instead you could easily spend that earned money on an air
operated hydraulic jack and have money left over. IMO.
I know this isn't an answer to the question here but it may be useful.
One time I made an IV bottle type of fluid reservoir for a hydraulic jack
that allowed the jack to be used in any position. I used a short piece of
PVC pipe and fitted it with a tube fitting. I also made a new fill plug for
the jack and drilled it and soldered a tubing fitting on the plug. I
attached a piece of tubing between the PVC pipe reservoir and the jack,
added hydraulic jack oil and then (the hard part) did my best to get all the
air out of the jack. The idea is to remove the air and completely fill the
hydraulic jacks internal reservoir so that air can't get to the pump. The
external reservoir then supplied the oil for the jack's ram displacement.
I hung my reservoir on the wall near the press I was using it on but it
could be designed to set on the floor. I think I could have improved on
removing the air from the jack with a brake bleeder vacuum pump kit but I
didn't have one at the time.