Hardinge Conquest 42 1991 OT "low lube alarm".

I have read previous post with the identical problem, with no real outcome. Low lube level comes up about every 19 minutes 40 seconds. I checked float on reservoir tank. It appears to be functioning properly, when it's down it opens the circuit, when it's up the circuit is closed and we have continuity. Next was the pressure switch. Ordered a new one and since there is no guage to indicate how much pressure is in the system, I installed a guage to check it. Comes up every 8 minutes, rises pressure to around 24, remains there for a few minutes, then drops of slowly. There is no immediate drop after it gets to 24 until about 5 minutes. Installed new switch, same alarm in 19 m 40 s. What the heck. Mess with the air pressure, it was at 72-73, set it to 80. Viola, no more alarm. Fast forward 5 weeks. Get low lube level alarm, but it's low. Add oil, everything is OK. A few hours later, low lube level alarm, for no reason.
Very frustrating.

We have two Conquest 42s, and one of them has this problem. I looked into fixing it a while ago but didn't get anywhere. Things weren't making sense, and more important issues came up. Maybe I'll take another whack at it to see if your results are the same as mine.

Is this an air opperated lube pump?

Mine are electric, but you mentioned bumping up the air pressure - and that it solved it for some time.

I have that issue on a 1990 Tornos with an air opperated Bijur. (you say that your machine is 1991, so ...)
I finally ran out of air pressure adjustment, and so that forced me to look further downstream, and I found what I think is an inline sensor, that also had an adjustment.
I played with that for a few seconds and my problem went away - for a while.
I'm sure that I will need to dink with that some more soon enough...


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I am Ox and I approve this h'yah post!

I have the impression that on my Hardinge GT that the machine looks at the pressure right after the pump cycles. If the filter is partially clogged the pressure could be low when that happens or the pressure sensor is faulty.

On the occassions I have run low on lube it takes a couple cycles to get the air out and have proper pressure when the pump cycles. I seem to remember starting the machine several times to force the pump to cycle. Not sure what the interval is on my GT but the pump does not run constantly. I assume the Conquest 42 would be similar.

Here is what I found downstream on my Tornos that I adjusted.
(same bat era, same bat pump?)

Maybe they git gunked up a bit after prox 30 years?



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I am Ox and I approve this h'yah post!

On both my machines, the lube pumps are electric. I don't see how the OP could have affected the lube alarm by changing the air pressure. From what I can tell, the two systems have nothing to do with each other. There is a lube filter just below the pump. Maybe that is clogged?

I have had to replace the screen on my electric pump recently, but if his is air powered - from my experience, yes - turning up the juice makes a difference.


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I am Ox and I approve this h'yah post!

This is absolutely no help to the OP but reminded me of a funny story.

I had an operator work for me one summer. The lathe threw a low lube alarm. He thought that meant it needed coolant.
So he starts dumping 5 gal buckets in til it was running across the floor coming out under the front of the machine.

Good times.