Ok, a few basics:
Force and Pressu Maximum force is simply the operating pressure times
the area of the PISTON (not the rod) Measure the outside diameter of the
cylinder, figure that the wall is about 1/4" or so. So 4-1/2" outside
diameter can be assumed to be 4" Your pump can be set up with a
pressure relief at all sorts of different points, 1000psi is fairly low,
3000 psi is right up there, maybe use 2000 or 2500 psi as a reasonable
point. So a 4" cylinder has 12.78 square inches and 2500 psi and would
produce 31,950 pounds of force.
GPM and speed: 1 gallon is 234 cubic inches so 1 gpm and a 4" cylinder
with 12.78 square inches would move 18" per minute 234/12.78=18).
(Pretty slow!)
Hp required: the hp forumla is gpm*psi/1740 so the example above would
take 1*2500/1740= 1.43 hp For a gas engine you want the hydrualic
rating to be something like 3/4 the gas engine rating. That would
calculate to 4.72 GPM MAX at 2500 psi for your 9hp engine.
Last thing is using 2 stage pumps. These have two sections, you use both
sections of a dual pump unit at low loads to give you high speeds, then
when the load increases one section drops out and you get high pressure
at much lower GPM rating. Sounds complicated, works well, especially for
smaller engines.
Take a look at item # 1012 at
www.northerntool.com This one will do
2.9 gpm at 2500psi so it would drive a 4" cylinder at 54" per minute
under full load, would do a 12" stroke for the bending in about 15
seconds. Bigger cylinder on the shear section would go slower but not as
far so it would cycle down in perhaps the same 15 seconds. Return stroke
would be at 11gpm so it would retract in 4 or 5 seconds. Item # 1056 is
slightly bigger would take more hp to drive, would run the cylinders
faster. They both have a 2" square bolt pattern that mates up with the
standard adapters.
I suspect that your pumps are in the 3 to 4 gpm range. YMMV
monkers wrote:
Seems I screwed up again, it was the "rod" that I measured, and
incorrectly called the piston. I looked in a catalog at some cylinders
of the same orientation and looked at the rod size compared to the
bore, and it is very different. I think Im dealing with a 4" bore and
the other is probably 5 or 6" bore. All Im trying to do is find out
what GPM the pump should be. I tried finding the valves on Parkers site
and got errors. I tried searching for the mfg. company and nothing
turned up. Can you guys tell me how to figure GPM with the info I have?
I couldnt find anything telling me the force required to bend 1"
rebar. I have emailed some companys with no answers yet.
Thanks guys, sorry to be such a pain
Craig