Mazak Nexus 250 lathe, with hydrolic pressure issue

[FanucIssues]

The fault will say something like hydrolic pressure down, but the pressure is fine, the same as our other machine. We replaced the pressure switch with one that had a wider range, and ordered a replacement. The machine ran fine, but when I put the replacement switch in, we started having problems with it faulting out. If we are to power down, and back up, it will run fine for five hours or so, then same thing power down, and then it will run...The time I had seen it do it, was when I clamped the chuck.

First off, how do those pressure switches work? Are they like a rheostat (sp?), or do they function differently? And secondly, any suggestions?

[Mazaholic]

As far as i know the pressure switch is like a micro switch...probably normally open,the pressure closes the switch.
If it only happens when you close the chuck, i'd make sure your clamp pedal isn't shorting out.
When the machine goes down,does it go into E-stop?..pressure alarm? or does it just shut down?
I would't rule out a short,they can play havoc on your nerves.

[FanucIssues]

It will just go into a pressure fault, the hydrolic motor will not even shut off. It could be a short, but it ran fine with the other switch (without the correct pressure range), but when I put the correct switch in it started acting up. I've adjusted it, the switch, but that doesn't seem to matter. I haven't asked how it ran last night, but I guess no news is good news. Thanks for the though, when I get time I will ring out the foot pedal.

[Mazaholic]

I'm not real familiar with the Nexus,but something else to consider is a loose or faulty ice cube relay.