Hydraulic press problems

[DaleJ]

Have hydraulic press running double acting ram, electric solenoid switching valve controls flow for extending and retracting ram. Ram extends without trouble but retraction stalls electric pump and trips breaker. With another hydraulic pump tied into double acting ram it extends and retracts without problem. Any help or ideas would be appreciated.

[qwert]

If you connected the test pump directly to the cyl and confirmed its proper operation, then you seem to have a problem with the electrical solenoid or valve not opening properly. Trouble-shooting the valve system will depend on type, I suspect a simple open center system. I suspect that the oil return to reservoir circuit is not opening and causing a hydraulic lock. I suggest you relieve all pressure in the system and confirm valve movement.

With any electric/solenoid system it is usually less messy to test the solenoids first if possible.

Good Luck, YMMV.

[YAFORDDIESEL]

does this retract system have a counterbalance valve?

[DaleJ]

Solenoid switching valve was working, but spool was a bit rough on the edges. Replaced switching valve. Pump is two stage and needs about 500 PSI to engage hi volume flow. There are two PRV's on unit, one is set at 2100 PSI, the other is adjusted to bypass at a lower pressure if required. Looks like a full tear-down is the answer.

Cylinder retraction oil flows backwards through the high pressure discharge line through switching valve.

[DaleJ]

Originally Posted by YAFORDDIESEL

does this retract system have a counterbalance valve?

No counterbalance valve, no flow reduction valve. By-pass pressure set with second PRV.

[winged1]

Originally Posted by DaleJ

Solenoid switching valve was working, but spool was a bit rough on the edges. Replaced switching valve. Pump is two stage and needs about 500 PSI to engage hi volume flow. There are two PRV's on unit, one is set at 2100 PSI, the other is adjusted to bypass at a lower pressure if required. Looks like a full tear-down is the answer.

Cylinder retraction oil flows backwards through the high pressure discharge line through switching valve.

A schematic is worth 10,000 words.

[DaleJ]

Originally Posted by winged1

A schematic is worth 10,000 words.

Wish I had a schematic. Can't figure out how to post attachment with I-phone.

[winged1]

A PRV could mean relief or reducing. Are these on pump outlet or elsewhere? An increase in pressure typically switches to pump low flow. Other than the directional valve, is any other component electrical?

[YAFORDDIESEL]

read all your posts

Did you manually push hydraulic spool with allen wrench to check if spool is fully shifting?

Maybe electric valve is not shifting completely to return port.

[DaleJ]

Pressure relief valve. Primary pressure relief protects unit from over-pressure, secondary pressure relief is for operator to set at enough pressure to do job intended. Both PRV's release back into hydraulic pump suction.

[DaleJ]

Originally Posted by YAFORDDIESEL

read all your posts

Did you manually push hydraulic spool with allen wrench to check if spool is fully shifting?

Maybe electric valve is not shifting completely to return port.

Spool is shifting. Switching valve is "D-03" makes turning it around easy. Turned it around. Still has problem retracting cylinder.

[winged1]

I've seen before, where a regen check valve is integral to the cylinder piston. A proportionally large rod could indicate regen, as would the action of fast approach. With cylinder fully retracted, dump cap line to bucket while applying retract to directional. Bypass from a regen check will show flow.

Wait, just reread and your stalling, so bypass in unlikely culprit. schematic time.

[YAFORDDIESEL]

pictures would help

[winged1]

However, if you do have integrated regen (no externals ), you may have a blocked port on your spool as part of the regen action. Reversing lines or spool could then give you the action you've indicated (stall).

[Got Juice?]

Originally Posted by winged1

However, if you do have integrated regen (no externals ), you may have a blocked port on your spool as part of the regen action. Reversing lines or spool could then give you the action you've indicated (stall).

This is my guess as well

[winged1]

Originally Posted by Got Juice?

This is my guess as well

In typical fashion, the problem likely started from a cylinder repair/replacement, where the integral check was overlooked. Just a guess without a schematic.

I'm still wondering what a '2 stage' pump is, and am wondering if the relief valve that dumps back to suction is really a relief valve.

[Got Juice?]

Originally Posted by winged1

In typical fashion, the problem likely started from a cylinder repair/replacement, where the integral check was overlooked. Just a guess without a schematic.

I'm still wondering what a '2 stage' pump is, and am wondering if the relief valve that dumps back to suction is really a relief valve.

With any repair, it takes such a small amount of FOD to stick a valve.

Unless a swash plate/piston EATON, I can't see it being 2 stage?

The second stage could be bypassed depending on the spool in a simple meter out configuration, or a variable check ball and spring or....even a compound

So many combinations without knowing the valve combo...

[DaleJ]

Got the hydraulic pump and valveing working properly. Problem was a partially blocked 1/4" check valve on return line to tank. Thanks for the help.

[winged1]

Good to hear. Hydraulics are fun, except for the dirty, oily, noisy, hot aspects.

[Got Juice?]

Originally Posted by DaleJ

Got the hydraulic pump and valveing working properly. Problem was a partially blocked 1/4" check valve on return line to tank. Thanks for the help.

Glad you found the problem!