I got a better look at the bender today here is what I can add to help:
Not homemade,just looks it, made by Midland Products Co from Mindland
Park NJ (will try to search for them in a minute) Model # QG3 serial #
10/5/71 . The two cylinders are as follows: 1 3/4 bore x 20" stroke, 2
3/8 bore x 14" stroke. The machine isnt running so the stroke may be
two inches less than stated, I measured the best I could get to
everything. The bracket that held the pump has a 3 1/8" center hole
with two holes (about 3/8" +or-) for mounting that are on 4 1/4
centers. Measurements taken with tape measure,not calipers.
The pump fed the 1st valve body,then the 2nd through that one. The
#`s are Parker serial # 08141901 model# VDP 11 D 44. The 2nd valve
body that runs the shear is Parker serial # 11141611 model# VDP 11 D
10. The B&S motor is 9HP and turns the pump in a clockwise direction,
facing the shaft. This is all the info I have so far, Im going to try
to figure out the size of the pump needed with this info. I have a
catalog that gives some formulas to find certain things given piston
size etc... I will also run these #`s by Parker to see what they say.
Again, thank you to all that are helping, Im sorry to be such a pain,
just want to get it right, and also learn a thing or two. Thanks again,
Craig

The two diameters I mentioned are the piston dia. How do I tell the
bore size , as it is different than piston dia. correct?

On 6 Apr 2005 09:31:21 -0700, "monkers" wrote:

The two diameters I mentioned are the piston dia. How do I tell the
bore size , as it is different than piston dia. correct?

The bore size is only a few thousandths different than the piston dia.
In fact, if a cylinder is called out as a 4" cylinder then the bore
will be 4 inches and the piston slightly smaller.
ERS

But the rod will be significantly smaller than the bore. eg a 4" bore
will likely have an 1-1/2" rod. Which would give you 12.56 square inches
out, and 10.79 square inches on the return stroke.

Eric R Snow wrote:
On 6 Apr 2005 09:31:21 -0700, "monkers" wrote:


The two diameters I mentioned are the piston dia. How do I tell the
bore size , as it is different than piston dia. correct?


The bore size is only a few thousandths different than the piston dia.
In fact, if a cylinder is called out as a 4" cylinder then the bore
will be 4 inches and the piston slightly smaller.
ERS

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

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

Roy,
Thank you for helping out a hydraulicly challenged individual! I
really appreciate you taking the time to explain this. I racked my
brain with a couple books and a Surplus Center catalog as a refrence
and tried all different formulas, but I had no way of knowing if I was
even in the ballpark. (I kept coming up with one pump they had that was
4GPM, but calculated that is would be closer to 5.4 GPM with the engine
speed.) Thanks again for your help,
Craig

If you are going to go out a buy a pump for this application, get the 2
speed version. The automatic downshift is much kinder to a gas engine
setup.

monkers wrote:

Roy,
Thank you for helping out a hydraulicly challenged individual! I
really appreciate you taking the time to explain this. I racked my
brain with a couple books and a Surplus Center catalog as a refrence
and tried all different formulas, but I had no way of knowing if I was
even in the ballpark. (I kept coming up with one pump they had that was
4GPM, but calculated that is would be closer to 5.4 GPM with the engine
speed.) Thanks again for your help,
Craig

On 6 Apr 2005 18:32:05 -0700, "monkers" wrote
something
.......and in reply I say!:

Operate the cylinder by hand, or with the help of some hand-operated
tools etc. See how much oil comes out/goes in if you take it right
out, fill it up, the push it right back. There is your capacity. If
you measure the stroke, you can also then work out the bore.

GPM will depend then entirely on how fast you want the machine to
operate.

Bending 1" rebar. The force required will depend a lot on the
configuration of the machine, and how sharply it bends the bar etc.
The further the piston is from the place where the rebar is actually
bent, the less force is required.

There are ways to get an idea of the forces, but the above would need
to be known. My ghuess is that a 4" cylinder running at the standard
2500 PSI should be way enough to bend 1" bar. But again, if you placed
the push right at the fulcrum that the bar reasted on, you would have
buckley's....

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


************************************************** ****************************************
WHY _ARE_ WE HERE?

Nick White --- HEAD:Hertz Music

remove ns from my header address to reply via email

!!
")
_/ )
( )
_//- \__/

On 6 Apr 2005 18:32:05 -0700, "monkers" wrote
something
.......and in reply I say!:

More ideas. They make hydro log splitters. I looked around and found
one that has a 9HP motor, which produces 16GPM. This will cycle a 24"
x 4" cylinder with a 2" rod. This is close to what you describe, and a
bit of math can work out the differences.

It claims 20 tons of force. At 2500 PSI and a 4" bore that seems a bit
optimistic,
#(2 ^2 * pi(3.14) = 12.6 in2 * 2500 PSI = 31500 lbs force / 2240
lbs/ton = 14 tons)

But some systems run at 3000 PSI. Even then I still get only 17 tons.
20 tons would need 3500 lbs.

Now it probably uses a double-speed pump. But without that, the cycle
time for _push_ would be:

4" * 24" capacity = 301 cu in = .175 cuft = 1.15 gals (imperial)

At 16 GPM, therefore I reckon about 5 seconds.

Then there is another 4-5 secs to come back again (the rod makes the
capacity smaller on the pull stroke).

If you use the 3.8 litre US "wet" gallon (I have never quite sat well
with all that wet and dry stuff G), the pump is actually only making
12GPM imperial, and the above times would be about 6.5 seconds push, 5
seconds pull.

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


************************************************** ****************************************
WHY _ARE_ WE HERE?

Nick White --- HEAD:Hertz Music

remove ns from my header address to reply via email

!!
")
_/ )
( )
_//- \__/