Hydraulic noise

Hi, I'm a farm owner. I recently built a 20-ton hydraulic press for pushing bushings and bearings, and for straightening bent shafting. It works
fine -- two-hand operation, a motor spool control so I can "nudge" work, and a two-stage pump to give good ram speed with a high end pressure.
But the NOISE! It darned near drives me out of the shop!
I've bunkered the pump/tank affair with concrete blocks and earth, and with a 2" thick drywall cover. That vastly reduced the noise coming directly from the pump. But the high pressure line (about 8' long), and even the press frame itself, just "rings" LOUD at the gearotor's frequency.
I guess I'm sensitive to that sound. But if I spend a couple of hours re-bushing an entire machine, I'm worn out from the sound.
I don't like wearing earplugs or muffs... they prevent me from hearing other important sounds in my work environment; so I'd like to eliminate the noise source.
My background is electronics, not hydraulics. I envision something like a "low pass filter" (r/c network) eliminating the "ripple".
Would I be correct in assuming that an air accumulator near the pump would eliminate this racket? Maybe that, and an oriface or flow control valve either upwind or downwind of the accumulator? I don't want to spend the money if it won't help.
If that's not the solution, or if there's more to it than that, I'd sure appreciate some help.
LLoyd
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It could be your hydraulic pump is cavitating. Google. If your machine was made by a US company you might call them up and ask them if a rebuild kit is available.
I was afraid that had happened to me on my ironworker. But then I tore it apart and cleaned the tank meticulously and refilled it with new fluid and now it's much quieter.
Maybe that would help you.
GWE
Lloyd E. Sponenburgh wrote:

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On Thu, 06 Jan 2005 07:12:05 -0800, Grant Erwin

Educated Guess: Check that the hydraulic system output relief valve is opening, and that it's set right. (Do you have a pressure gauge on the pump output, or on the press cylinder ram?)
If the pump is churning away at it's max pressure whenever idle, that would cause excess noise from cavitation - the relief valve would allow some fluid to circulate back to the tank under control. I'd turn the pressure down a notch and see what happens...
If that works, might even try a second relief valve set far lower with a ball or solenoid valve in front of it, for the majority of the time when you don't need the press' maximum output tonnage.
(If I build a powered press, it'll probably use an Enerpac style air-over-hydraulic pump, they're stone quiet when not in use, and they creep nicely when throttled back... I have one with an old 3M MS2 cable splicing head attached, all I need is a high-pressure hydraulic coupler to allow it's use elsewhere.)
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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| Hi, | I'm a farm owner. I recently built a 20-ton hydraulic press for pushing | bushings and bearings, and for straightening bent shafting. It works | fine -- two-hand operation, a motor spool control so I can "nudge" work, and | a two-stage pump to give good ram speed with a high end pressure. | | But the NOISE! It darned near drives me out of the shop! |
Last time I looked, Home Depot was selling sound board for about seven bucks a sheet. Won't solve your hydraulic issues, but it will kill some of the noise. Layer it with sheet rock to make the dampening effect even better.
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"Lloyd E. Sponenburgh" wrote:

If you have the noise problem with the valve in neutral, you have either a port plumbing issue or a spool problem, the hp line vibrating like that, suggests a back pressure problem. Try running with the hp hose returning into the tank.
Tom
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"Tom" <> wrote in message > "Lloyd E. Sponenburgh" wrote:

press for pushing

shafting. It works

can "nudge" work, and

pressure.
shop!
and earth, and with

coming directly

press frame itself,

couple of hours

sound.
me from hearing other

eliminate the noise

envision something like a

"ripple".
near the pump would

flow control valve

want to spend the

than that, I'd sure

you
problem.
Do you know if you have/need an open center control valve? Sounds to me like you have a closed center valve and the pump is relieving itself at max pressure all the time. Phil
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I have an open center bypass (safety) valve and an open center control valve. When the valves are centered, the pump circulates to the tank at essentially zero pressure.
My pressure gauge is on the HP line, on the pump side of the control valve -- so I can see the pressure the pump is delivering, rather than the working pressure at the cylinder.
The system makes a "screech" when the relief valve opens under full pressure. That I expect, and don't have a problem with the intermittent noise. The noise I'm fussing over is continuous while the pump is running at zero pressure -- just recirculating.
The pump doesn't appear to be cavitating. I've installed a much larger return filter than necessary, and the intake screen to the pump is clean. I'm running a low-vis oil comparable to the newer Ford tractor gearcase/lift oils (about 5W-20 equivalent). Those oils run quieter than the older straight-30 I used to use. Also, FWIW, the pump is NOT submerged in oil, but a free-in-air design mounted on a motor-mount plate.
However, as in my original post... it's not the direct noise from the pump and motor. I've suppressed that with earthworks and drywall. It's the "ringing" of the HP line and press frame I'm trying to eliminate.
LLoyd
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gearcase/lift
Try put an acumulator(sp?) on the hp line. That should dampen out the pressure pulses a bit. Pat
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On Fri, 07 Jan 2005 13:19:36 GMT, "Lloyd E. Sponenburgh"
......and in reply I say!:
remove ns from my header address to reply via email
From my (limited) experience, ........
most of my machinery makes so much noise anyway, a little hydraulic whine is nothing! <G>
......you have covered the most obvious reasons for cavitation with good flow. If the pump is not submerged, you may be getting cavitation because it's sucking a bit of air. IMLE, this may get _worse_ with low pressure, higher flow in open centre. Is there any sign of bubbling in the reserve tank? It may also be simply because the pump has to suck to a height and is starved. Is there any sort of non-return valve on the outlet of the tank, before the pump, that may be causing a restriction?

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On Fri, 07 Jan 2005 13:19:36 GMT, "Lloyd E. Sponenburgh"
<snip>

Can you substitute flexible hydraulic hose for the (presumably) rigid metallic pipe?
Mark Rand RTFM
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"Lloyd E. Sponenburgh" wrote:

Perhaps you could supply the make & type of pump and describe the the the way in which it is plumbed to the tank? What height does the pump have to draw the oil from the tank?
Also, how do you know that "the pump circulates to the tank at essentially zero pressure."?
Tom
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It's a cheap Prince 11gpm two-stage pump. Cheap. Hooked up to a 1725RPM 2HP pool pump motor. Lovejoy coupling.
The pump is _below_ the fluid level in the reservior. Actually, about 8" below.
I have a pressure gauge on the HP line, just before the ONLY restrictions in the bypass circuit -- namely, the OC bypass valve itself.
The return lines are larger than the HP line. The HP line is 1/2", 3-wire, neoprene coated standard stuff from NAPA.
LLoyd
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"Lloyd E. Sponenburgh" wrote:

For someone asking for help, one gets the impression that you're not amenable to suggestion. Either start from basics or forget it. If you have a noise problem, the only way is to eliminate potential causes. That you appear to have an excessively noisy pump can only be confirmed if you remove any valves and run it straight into the tank. Noise can be caused by elbows too close to the intake side of the pump and causing cavitation. Your problem also can be the result of a poorly assembled hose. Assume nothing. I looked at a press a couple of years ago that exhibited just about identical symtoms to yours. Found that the valve, purportedly, an open center unit, was set up as a closed center and required the removal of a blanking plug to act per description. The result was a noise level about 1/10 of previous.
Tom
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proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email

PMFJI. Ease up. He is attending to your questions.

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Old Nick wrote:

WPYC?
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