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Mori SL150 Hydraulic pump troubles

joeby

Cast Iron
Joined
Mar 22, 2006
Location
Central PA
Hi all,

I am working on the hydraulic pump on a SL150 lathe. The problem started with the overload tripping after about 10 seconds of run time on the motor. I pulled the motor off the hydraulic unit and found the oil seal had failed and the motor had filled with hydraulic oil.
I drained the oil and cleaned the inside of the motor out as best I could with compressed air. New bearings have been installed along with a new seal. The motor turns fine and I checked the windings with an ohmmeter. No shorts to ground and all three leads read about 5 to 5.5 ohms.
What should I be seeing for resistance normally? Can I check anything else out on this without sending it out? The motor will be replaced if necessary, I'm basically trying to get the machine up again as quickly as possible.
The motor has been reinstalled and has the same problem, 10 second or so run and trips the overload. Am I fighting a losing battle here? Just wondering if I should try something else, or just order a replacement motor now and wait it out. I just want to be sure that the motor is the issue, and nothing else is causing grief.
Any help here is appreciated, thanks,

Kevin
 
Just an update, I had some time to do some checking on the SL150 today. I checked the voltage on the motor leads and I'm getting 220V between any of the three leads ,but checking from the leads to ground I have 220V on L1 220V on L3, and 15V on L2.

That doesn't seem right to me, or is that actually expected voltage readings?

Kevin
 
trace your leads back to the source- you could have bad contacts in the motor starter or a bad fuse in the circuit. Should be pretty easy to troubleshoot. Do you have schematics for the machine- that would make it much easier to figure out things, but 15 v on that one leg is not what one would expect- . You have found the problem, now figure out why. The motor is probably just fine.
 
I traced the wiring back, same results. I checked the line in and got the same. We had one of the company electricians come in and check from there, apparently this runs from a corner grounded delta transformer and he said the voltages are fine. I ain't no electrician, so I won't argue with what he says, still doesn't seem right to me though.

Anyway, once the motor quit the second time, I rechecked the windings and they were all shorted to ground. The thing sat for a couple of days until I got back to it and they checked fine. I figure the insulation is failing from the oil contamination.

We ordered a replacement pump and motor and the machine is back up and running now. I am still wondering if drying the old motor in an oven at low temperature might get it going again. Just my curiosity though, it lasted 20 years, so the next replacement will be someone else's worry.

Kevin
 








 
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