Need help diagnosing an auto lube pump problem

DavidScott · Dec 14, 2018

The lube pump is a Lube co., see the photo below. The problem is ever since I got the used machine 4-1/2 years ago I have had problems with a low-pressure alarm. At first if I kept the tank above 1/2 full it was fine, then I had to keep the oil above 70 degrees. A few days ago it got a lot worse where raising the oil temp to 80 degrees was barely keeping it from alarming out with a full tank.

Side note that may be of importance. I have also been getting a thermal overload alarm 1005 once in a while for the last 2 years. I would shut the machine down, reset the relay, and all was well for a few more months. In the last few months when I would let the oil temp get too low and get the low oil pressure alarm occasionally the thermal overload alarm would go off at at the same time, this has happened 4 or 5 times now.

Control is a Yasnac J300 on a 2001 Kitamura that was not turned off for it's first 9 years so the pump probably has a lot of hours on it. It is a geared pump with an induction motor. Oil is Vactra #2. I put a new filter in the tank pickup 1-1/2 years ago which made no difference. I drained it a few days ago in preparation of taking it apart so that is why the tank is empty.

Any ideas or suggestions about what the problem could be before I take it apart? This is the first time I have taken one of these things apart so I am open to any insights.

Tonytn36 · Dec 14, 2018

The guys I dealt with over at Lube were great to work with last time I was in need (few years ago now). Might want to put in a pressure gauge to see if it is actually building pressure because it might just be a bad pressure switch.

Bobw · Dec 14, 2018

Have you been using less and less oil???

If yes, then, as you already know its not pumping properly for some reason...

If you are using the same amount of oil.. I'd go looking at the pressure sensor, its probably
clogged up with 17 years of garbage...

First thing I thought when I saw just the title, is that your tank is full of crap, and filters
are clogged... But.. You already changed the filter a while back.. Might have just been a lot
of crap in there.

You already said you are pulling the tank.. If that looks good, maybe unhook from the lube lines and
run some solvent through, maybe mineral spirits or something...

One last thought.. Is there maybe a secondary filter screen or filter in line somewhere on/in the pump
that might be clogged up???

DavidScott · Dec 14, 2018

When I replaced the filter there was plenty of goo in the bottom of the tank but the filter didn't look too bad. I did clean out the tank real well before putting it back together. It still uses the same amount of oil and I have pulled the waycovers back a few times to make sure everything is getting oil. When I first got the machine I made sure all of the metering units were working and the plastic lube lines looked to be in excellent shape.

I have not read about there being more than one filter in the system. There is an antibackflow valve that may get debrise in it and leak causing the alarm.

I have been thinking a pressure gage would be nice, easy enough to install it, just have to order it and get it shipped here.

Any ideas about it tripping the relay in the cabinet?

ewlsey · Dec 14, 2018

The spec sheet shows that unit has a built in pressure switch. I guess you need to find out if it is being used, or a remote switch.

I'd be putting an amp clamp on it.

The pressure part is confusing. The motor is pulling a lot of amps, indicating it is trying to pump harder than is should = high pressure. But your alarm is for low pressure = not enough back pressure or pump not working correctly.

Bobw · Dec 14, 2018

DavidScott said:
I have been thinking a pressure gage would be nice, easy enough to install it, just have to order it and get it shipped here.

Any ideas about it tripping the relay in the cabinet?

Order??? Even a POS air pressure gage off a Harbor Freight air compressor will do you until
the insides go bad. Napa has oil pressure gages.. Pressure is pressure.

One other thing to think about, and a pressure gage will tell you this. There are generally
2 types of oiling injectors/systems.. The kind that pumps and builds pressure and then
slowly bleeds it off.. And then the kind that spikes the pressure pretty darn high and that
fires off the metering valves, and then the pressure drops really fast.

Definitely get a pressure gage plumbed in before you start tearing stuff down and replacing stuff.

As for firing it off, I have no idea what that pump is.. I have one machine that a piston
is pushed up slowly by a cam and then let fall, and I can just pull the piston up by hand for
a few seconds the cylinder fills and then I let go, and it pressurizes. Other machines I have,
there is an air valve I can fire off with a button on the side of the valve.

DavidScott · Dec 14, 2018

Forgot about Napa, I will find out if they have a gage that will work. The best I might have only goes to 160 psi, the operating pressure of my lubricator is 283 psi. Reading in the lubricator section of my manual it says it will alarm out if the pressure is ever more than 247 psi or less than 247 psi at the time of completion of the discharge (pump on) cycle the pressure switch operates. The optional pressure gage is rated to 711 psi.

Yep, I remember the air over oil pump on the Fadal I worked on, real well. After a few years I noticed the oil quit going down in the tank sight glass. Turns out the piston was stuck in the compressed position, the return spring wasn't strong enough to overcome the sticky deposits from the way lube. We didn't have a shut off valve for the compressed air so it never got shut off, and when the power to the machine got cut it opened the air valve to the way lube pump, so the piston was always compressed while the power was off. After fixing the pump I put a valve in to turn the air off when the machine was off, which later caused the machine to try tearing off the tool carousel during a tool change, but that's another story.

Since I have your attention, what is an R1/8 threaded connection? This is what the pressure gage should have. Well I looked it up and looks like it is a Brithish pipe thread or Japanese pipe thread, complete with 55 degrees and rounded crest and bottom of the threads. I doubt Napa will have that.

machtool · Dec 15, 2018

DavidScott said:
Since I have your attention, what is an R1/8 threaded connection? This is what the pressure gage should have.

It is what we once called 1/8 BSPT- tapered. Its 28 T.P.I, where you NPT guys will be 27 T.P.I You wouldn't be the first one that's interchanged them. It would work with a drop of hydraulic loctite.

McMaster do them in BSPT. McMaster-Carr

Regards Phil.

adama · Dec 15, 2018

Other cause is simple, its not building pressure as theres a leak down stream of the pump, hose has worn a hole etc, does not take much for a lube pump not to hit full pressure. Even a slightly damaged metering valve can cause it.

Tonytn36 · Dec 15, 2018

R is designed to work with either NPT or BSPP threads. It's kind of a hybrid. That is what I stock in our engineering shop because of that.

DavidScott · Dec 15, 2018

Well, the local Napa doesn't have any gages that go up to 300 psi so I will have to order one on Monday. In the mean time I will try to find out how many amps the motor is pulling. My gut feeling is the motor is the problem.

tonymor · Dec 17, 2018

We had a new lathe 2/3 years ago that was throwing this alarm every now and again. Easy fix was to change the parameter for the length of time the pump ran for and allow a little extra time for pressure to build. Extra second or two might be the difference between getting the alarm and not. Not sure if this will work for your machine but might be worth looking into.

cpifer3 · Dec 17, 2018

I have the same lube pump on a MITS M50H horizontal mill. I get the low P/S ALARM also from time to time. I to have cleaned the stone like filter, cleaned the tank, cleaned all metering valves etc, but still get it from time to time. I have a gauge on mine with the red tell tale needle, so I can always be sure that at least its making pressure, (mine makes around 300psi using an ISO 68 oil), I even tried jumping the pressure switch on mine and still got the alarm even with the switch jumped!!! This has been a big problem for me, as it stops the program when this alarm pops up. Mine will spike to pressure, hold for like 20 to 30 seconds, and then drop back to 0. Seems to cycle the same way weather the alarm is activated or not. Good luck, Ill be watching this thread for sure.

DavidScott · Dec 19, 2018

I got the pressure gage today and actually have some time to work on it. Here are some photos to help explaine what I have as I have a few questions that you may be able to answer before I figure them out putzing with it.
1) Are both power wires to the motor hot or is only one of them? Wires 1 and 2. I only have a multimeter to test amp draw and was wondering if I only need to test one wire or both? Draw is supposed to be .33 amps, meter is good to 5.
2) Pressure alarm switch- The manual says the singnal is only sent upon abnormality. Can I remove the wire so it does not send the alarm signal? Wire 6.

The wires in the top of the left photo are from the machine, lower wires go to the lubricator parts.
The relay in the right photo is the one that occasionally trips. From the schematics that came with my mill it looks like the lubricator is the only thing connected to it. Since normal load is .33 amps is this thing perhaps set just a little too low?

While waiting for answeres I will be putting it back together, filling with oil, and installing the pressure gage. Next is figure out load amps and pressers at the different cycle points.

Thanks for any help.

ewlsey · Dec 19, 2018

Current should be the same anywhere in the circuit, so pull whichever wire you like and insert your meter in series.

I see no harm in disconnecting the alarm signal wires.

That's a thermal overload that protects the lube pump motor. If it's supposed to be .33 amps, that's where it should be set. If the motor is pulling more than .33 amps, something is wrong with the motor, or something is wrong with the lube circuit and overloading the motor.

Tonytn36 · Dec 19, 2018

Careful with the P/S wires, the PLC may be looking for it to toggle on and off.

DavidScott · Dec 19, 2018

When I first powered up the mill the lubricator pump started right up drawing .34-.35 amps and imediately built up 300 psi. The second time it turned on it was drawing .61-.63 amps and the pressure was bobing from 0 to 40 psi. After 10 seconds of this the motor quit spinning. I grabbed a philips screwdriver, only thing within reach, stuck the tip in the centerdrilled hole in the motor shaft, spun the shaft a little in the wrong direction and the motor started right up building pressure and finishing the cycle without an alarm. The next 2 cycles, 14 minutes apart, have been normal without issue. It draws .34-.35 amps, right on 300 psi for 45 seconds, motor shuts off and the pressure imediately drops to 0. It is a 200 volt 2 pole motor with a ball bearing on the end I can see. Any ideas what to do next?

ewlsey · Dec 19, 2018

I'd check the voltage when it has one of those weird episodes. It could be your contactor is not closing right and not sending full voltage. Other than that, I think your headed for a new pump.

DavidScott · Dec 19, 2018

I have watched it go through 4 more cycles that have all been normal. The voltage on the last cycle was 215. The supply voltage is around 218, mill wants 200. The reason is the other machine supplied by the phase converter wants 220, and it was here first.

Maybe a dumb question but do I measure the voltage hot to hot? Leg to ground was around 90 and 120 volts for the two hot wires.

I will try agin in the morning when it is cold and hope it acts up again so I can measure the voltage during a pump cycle.

Is there no taking the pump apart to see if there is an obvious issue that may be repaired?

ewlsey, thank you for your help.

huleo · Dec 20, 2018

I will bet my left titty that either the sensor is not seeing pressure or the wiring is fubar. Get the pressure switch off and all will be revealed.

Need help diagnosing an auto lube pump problem

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