Enerpac hydraulic pump modification

rbcmetalwork · Jul 28, 2017

I have an Enerpac PUD-1100B electric hydraulic pump. This is an economy model does not have a hold feature. It does have an electric solenoid dump valve. A momentary switch runs the pump which advances a single acting cylinder. Releasing this switch opens the solenoid valve which dumps the fluid back to the tank.

Can I re-wire this so that the solenoid valve is energized and closed until I switch it off causing it to dump the fluid? Opinions/advice?

DDoug · Jul 28, 2017

I think it's wired backwards as it is.....

IIRC after the pump shuts off, it should hold until you
energize the solenoid to dump back to tank.

rbcmetalwork · Jul 28, 2017

Per Enerpac

"PUD-1100B/E and PUD-1101B/E Models
The PUD-1100B/E and PUD-1101B/E operate single-acting
cylinders where the hold function is not necessary. Pressing the
pendant switch starts the motor and advances the cylinder. When
the switch is released, the cylinder will retract."

DDoug · Jul 28, 2017

rbcmetalwork said:
Per Enerpac

"PUD-1100B/E and PUD-1101B/E Models
The PUD-1100B/E and PUD-1101B/E operate single-acting
cylinders where the hold function is not necessary. Pressing the
pendant switch starts the motor and advances the cylinder. When
the switch is released, the cylinder will retract."

Do you want my help or do you want to play lawyer ?

Pretty much every enerpac style pump I have encountered is as
I have written.

What would be so bad about you unhooking qty (2) wires to the solenoid, and putting them on the other push button ?

Better yet, add a DPDT switch (and nicely labeled) to switch
the action of the pump/pushbuttons, enabling you
to simply switch back to the original configuration.

rbcmetalwork · Jul 28, 2017

I'll try it. Thanks, Doug.

extropic · Jul 28, 2017

Alternatively, rather than modify the Enerpac pump unit, voiding any warranty and turning it into what it ain't, you could add (between the pump and the cylinder) a check valve and a secondary "return to reservoir" path controlled by a valve or solenoid? YMMV

By the way, I appreciate (am not offended by) your quoting the Enerpac catalog description. It shows you've done some homework.
No doubt, Doug will soon pass that bug that's crawled up his arse.

Miamijerry · Jan 24, 2020

Yes I realize that this is a very old thread.

Bought a HK PORTER HKE102A, which appear to be similar to the low end Enerpac hydraulic pumps. It only would extend and as soon as you released the motor switch, it would retract. Not what I was looking for...

It has the hold solenoid, but it is wired to close the return only while the motor operates. So I Re-wired it to allow for separate control of the "Hold Solenoid".

Now; Motor button depress, extends ram, releasing motor button the ram is in hold,
Operating new "Release" button , and the ram retracts. Ram also retracts when main power is removed.

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