Enerpac hydraulic pump

[agrotron]

Hi guys. I know there are some very knowledgeable hydraulic chaps on this forum so thought i would ask if you can help. Have got this enerpac connected on the back of a milling machine to operate a clamp and it use to build up to certain pressure then just stop. Now it appears to be pumping constant as if its not holding the pressure. I am a bit lost how its all connected up and how/if you can set the pressure. As per pic can anyone tell me what the parts are in the pic? Any advice appreciated @Smiley .

 

[Kevm]

The valve circled looks like a relief valve, but if you just put a relief valve on that then wound the pressure up on the air it would constantly pump and vent over the relief.
maybe you just need to reduce the air pressure at the regulator, or have you got an internal leak somewhere?

Edit, I can now see an airline going into that valve so it is more than just a relief valve, without seeing a proper circuit diagram it's difficult to say whats going on.

 

[tinman]

it looks like its either a air operated check valve or a dump valve, both are similar mind but without standing in front of it its a guess.

there is a strange pipe arrangement there.
the pipe out of it returns to the block.
is the clamp air operated, buttons? with a spring return?
to me it looks like there is two pipes on the pressure side, the one on the gauge and that valve you marked, and the other is cumming out of the end that the electric valve with the cable is attached to, what that valve is i cant say for sure but it looks like if there is no other pipe out of it then it may be a pressure sensing valve.

now if that all was the case and im just guessing, then when you give it air it pumps oil to the gauge side and out of the end at the same time, looks like that pipe then goes to the clamp?, if so, the clamp dose its thing and looks like it also electrically senses the pressure build up that the mill would need to know about but at this stage its clamped.
when you release it, im assuming its an air operated button/valve (that may be originally operated electrically through a air valve somewhere else (wherever the air pipes are cumming from )) its sending an air signal to the valve you've highlighted and in turn releasing the pressure off the clamp and letting the oil dump back to tank.
again, that's an assumption tho.

if its the case, and you'd have to confirm if the pressure side is indeed going to the two ports i mentioned.
and if the clamp is a single acting spring return then its possible the air valve is letting the pressure by, its not fit to make the pressure setting on the electric valve so it pumps away.
its also possible the pump internals are leaking, not making the pressure setting and again it would pump away.

you could see if when it was pumping if it was letting oil back to tank via that short pipe if indeed that's what it dose, if so then you could blank it off on the valve side and see if she still pumps all the time, essentially you would of dead ended the return so oil couldn't escape iykwim.

now a word of warning, im not suggesting you go pullin it apart and be dead ending things unless your competent, im onoy suggesting what id probably do, that is, as long as its all plumbed the way i think it is from my office chair.

 

[agrotron]

@tinman Cheers. Your description describes exactly what it does I think . There is an air valve With a solinoid connected and when the switch is turned on the clamp closes and when the switch is turned off the clamp opens (pressure is released) so I presume it is a dump valve. After a looking at it a bit more today the valve with the cable on is as you said a pressure switch. This has been put in so the mill won’t work if that clamp isn’t pressurised.

It appears if the pump is leaking internally as it drops pressure. I think I will replace the air powered pump with a hand pump to check if the cylinders on the clamp are leaking or if it is the pump. Cheers for your help.

 

[tinman]

if the cylinders are single acting then they wont be leaking or you would see it, i don't think they are double acting.

if the pressure is dropping then id open that air valve and see if there might be an o ring faulty or a seat damaged slightly.
it would let the pressure escape resulting in the constant pumping.
you could loosen the short pipe when its trying to clamp and see if there is oil pressure in it, just crack it first (have the safety gear on) and see if there is oil flow, if there is then the air valve is letting it past and it would need further inspection.
again, that's basing it actually dose what i think it dose.

 

[tomlad]

No disrespect to anyone I know we all dick around too much with stuff
Be careful with hydraulics

 

[tinman]

Your Damned if you do and your Damned if you don't eh!.

The op asked a question, not many answered..., I gave him my advice which I'd hope got him a solution to his problem while working on return lines, I mentioned safety, what more can I do other than not say anything and tbh, I think that's good policy on this forum of late.

Pity anyone I know wasnt about to answer his question when he asked it a whole 24hrs before I came along, ye could of done out a safety statement for him before ye got started.

 

[tomlad]

No disrespect intended sir

 

[tinman]

I understand that.

 

[tomlad]

I think my point was really i did realise till watching ave just how dangerous hydraulic injection is , i ve been dicking around with farm crap for some time.......