"Tom" wrote in message "Lloyd E. Sponenburgh" wrote:

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

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

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