Peddinghaus iron worker hydraulic system problem, semi OT

[Mcgyver]

I have an Peddinghaus iron worker and the hydraulic system for the punch is making an unusual noise and motion as per the video below - afaik it should smooth and quiet movement downwards with the bump bump bump. There is a slight flicker in the pressure at the bumps. There’s still plenty of oomph for punching but I’d like to figure out what’s wrong and fix it. The shear (separate cylinder) works perfectly, so it’s not the pump. My guess is its a valve but I don’t much about hydraulics so thought see if any of you recognize the behavior

A couple of videos and the hydraulics diagram are below. Thanks for any help and suggestions.

https://www.youtube.com/watch?v=nOiMmjWG9VQ

https://www.youtube.com/watch?v=AQmwwEua1Fc

hydraulic diagram:

https://drive.google.com/file/d/1eDSXSp1aZtC6TyS0kOdMRi-2yMYFxC72/view?usp=sharing

[3 Phase Lightbulb]

Seems like the solenoid or the solenoid driver/FET might be defective?

[Mcgyver]

good point, I could see how if the solenoid was banging away it might explain it.

[reggie_obe]

Separate control for the shear or a selector switch as on the Scottsman? Does the control station have a jog button? The action on the punch looks like what you get with "jog".

[3 Phase Lightbulb]

good point, I could see how if the solenoid was banging away it might explain it.

If you have easy access to the solenoid coil/contacts, maybe you can see if power to the solenoid is getting interrupted at the frequency you hear. Or if you can measure current, maybe you'll see the current fluctuate at the same frequency indicating something with the solenoid or the power to the solenoid might be fluctuating. Or maybe just putting your finger on it you might feel it

[Black Forest]

If it has separate solenoid valves for the different stations then it would be simple to swap the coils from the good station valve to the bumping station. If the problem followed the coils then you would know. That would be an easy test to make.

[Mcgyver]

we're getting a snow storm here so didn't go into today (plant's a 100 miles away) but will try these ideas later in the week. thanks

[3 Phase Lightbulb]

Place one finger on the solenoid, place the other finger under the ram and see if you can correlate the two

[Tim Clarke]

Almost certain to be a broken spring in the valve. Ran across this all too often in 40 years of fixing mobile hydraulics. A second guess. would be an Oring in the pilot assy. A teardown is needed. No fear, the cell phone camera is your friend. The oily mess is the worst part.

[reggie_obe]

News of the ironworker?

[Mcgyver]

Haven't been in yet, probably tomorrow

[Mcgyver]

Had a chance to work on this yesterday. I couldn't see how to orient things to swap them, but notice too late that the bottom of the solenoid valve rotated, so maybe that was it.

I'm guessing the largest block at the bottom is a manifold or similar. Each value assembly as what looks like smaller valve on top when the solenoid plug is. I'm guessing the solenoid valve turns a small flow that is used to turn on a larger valve?

I only had a time to get the right side apart, the lines in manifold under it go to punch cylinder. It would seem odd if the valves above the lines weren't controlling them, i.e valve on the right controls out lines on the right, but I can't say for absolute certainty.



Here's the small valve on top. Not sure how to get it further apart? Doesn't seem like there is anything wrong, but light was too poor to carefully check O rings (brought it home and will do so)



This is what I call the main valve, a seems like a simple assembly, spring are in both are not broken

[Tim Clarke]

I think what you have apart,so far, is the pilot valve. This ports oil pressure to shift the spool that actually sends oil to the cylinder. You're doing fine, next step is to dig in a little farther.

[Mcgyver]

Hi Tim, wouldn't the pilot valve be photo 2 and the spool 3 and 4? The thing in 3 & 4 has a cylinder running through the centre with lots of holes in it - us that the spool?

Any hint how the pilot (if thats what it is , photo 2) comes apart?

[Tim Clarke]

Hi Tim, wouldn't the pilot valve be photo 2 and the spool 3 and 4? The thing in 3 & 4 has a cylinder running through the centre with lots of holes in it - us that the spool?

Any hint how the pilot (if thats what it is , photo 2) comes apart?

Yes, I believe the unit in photo 2 is your pilot, it's the part with the operating coil. The figure near the bottom shows how the oil is ported, the center shows the letters p and t, which should be pressure and tank. the left shows straight thru, and the one on the right shows that the flow is reversed. The figure also shows a spring on each end, which means that the spool inside is centered, blocking flow.

This valve is configured a little different than I've seen before, I don't recognize the brand. The spool may have necks, or drilled passages, or milled slots, or a combination of any of these. Some are also hollow. The body is usually cast iron, with passages cast in. There should be no high pressure seals around the spool, the bore for it is a very close fit for the spool. There may be o rings at the ends of the spool to stop leaks, but the high pressure is held by the close fit. That being said, any tiny particle will bring these valves to a stop, or worse yet a partial failure. I've pulled out cylinder packing, O ring parts, and other debris from these. The material usually comes from worn out components elsewhere in the system. Probably the most maddening is hunks from the inside of hydraulic hoses.

The bores for the spools are straight thru in all I've seen. They need to be so they can be lapped by the manufacturer. So, the spools should pull out. If there's crap hanging the valve up you may be in for grief. This happens when there's something stuck in a casting port, and hanging partway into the area the spool travels. So, keep looking, you need to confirm this valve assy. is moving freely. I can't tell from the photos, but many valves have a troubleshooting feature, a pin in the center of each end of the pilot assy that allows you to operate the valve manually by pushing with a pin punch or similar.

Wishing you success, TC