On 2011-11-05, Ignoramus7775 wrote:
On 2011-11-05, DoN. Nichols wrote:
[ ... ]
There are liquid-filled (often glycerine) hydraulic pressure
gauges. You would need to know the diameter of the piston to calculate
the load from that, and of course subtract the empty load pressure from
the pressure with an actual load in place.
[ ... ]
I would suggest starting with the piston diameter, and
calculating the likely pressure range (multiply by two if the piston
pushes a roller chain gear up) before ordering a gauge. I suspect that
the lift does (or certainly *should*) not go to 10,000 PSI for example.
Don. thanks. I believe that I do not need to do any calculations. If I
assume that P = A + B * W, then all I need to know to find A and B is
the pressure with nothing on the forks, and the pressure with, say, 2
tons on the forks. Once I know A and B, I can make a little table on a
card and put it next to the gauge.
Yes -- that would work -- except that I was suggesting a way to
predict the top end of the scale -- do you need the 10,000 PSI one, or
is a 3,000 PSI one all you need. The closer to the range of loads you
need the more accurate your readings will be.
Does the documentation for the forklift list the maximum
hydraulic pressure allowed? Or the diameter of the piston? If only the
latter, take that, convert to square inches, and divide into the maximum
allowed load (plus perhaps an additional 500 lbs or so for the forks and
carrier) to see what size you need.
For hydraulics, I would rather buy something new at McMaster for $40,
than something unknown on ebay for $9.95 plus $8 shipping.
Have you priced the 10,000 PSI ones at McMaster Carr? Note that
the glycerin filling is to damp vibration of the needle with the pumps
pulsation.
Looking at the McMaster Carr catalog, the glyderine filled ones
range beteen $132.00 and $215.00 depending on size (2-1/2" or 4"
diameter) and where the connectionis (bottom, center back or lower
back. Ahnt it appears to e the same for pressure ranges between 30 PSI
max and 10,000 PSI max. Expensive enough so you want to calculate the
needed pressure range so you only have to buy *one*.
These are on the web based catalog page 551.
And no -- you don't want to use one designed for gas pressures
as a hydraulic gauge.
Thanks, though, for confirming that it is doable.
I've seen presses for forming something or other at work with
such a gauge mounted on it. You could also add one to a hydraulic arbor
press ('H' press) or the like. But you do need to know the maximum
pressure needed or allowed -- and a bit over that so you can tell
between right at the limit and the needle pressing hard against the stop
pin. :-)
Looks as though there are silicone oil filled ones, as well as
the glycerine ones in the McMaster Carr catalog.
Good Luck,
DoN.
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