zerk fittings on motor?

I have a couple of 7.5 hp 3 phase 184 frame motors. Both have zerk fittings. I
don't normally see zerk fittings on motors fitted with ball bearings, which I
assume these motors have. I'm wondering if I should pump oil in there or grease
- anyone know? One is a Baldor motor but the model is no longer referenced on
the Baldor Web page, or I'd just look it up there. The other is an older US-made
motor, don't remember the manufacturer, but I highly doubt they're still around,
probably 1970s vintage.
GWE
Reply to
Grant Erwin
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Not saying I'm right here, but I have a number of large motors with zerks. I give them all one shot/zerk every year. So far, the world hasn't crumbled.
Karl
Reply to
Karl Townsend
Sorry, insert lithium grease.
Karl
"Karl Townsend" wrote in message news:43a404ef$0$233$ snipped-for-privacy@auth.newsreader.octanews.com...
Reply to
Karl Townsend
Most older motors had zerks on them. They should be greased annually with two squirts of the grease gun, according to most manufacturers. The danger is in over-greasing. It blows out the seals and leaks grease into the motor and leads to bearing failure. Modern motors use sealed bearings that require no lube for the life of the motor, then you just install a new set. Bugs
Reply to
Bugs
Before you pump grease in them, look on the other side from the fitting for a plug. Pull the plug out first and only pump a couple of pumps into the fitting. Too much grease and it will go into the motor if you dont have the other plug out.
John
Reply to
John
Allot of manufacturers STILL have zerks on their motors. I install and service commercial HVAC equipment and see grease zerks on new equipment all the time, so it is not a modern thing! Greg
Reply to
Greg O
Ahh! Reminds me of my Navy Life. "To grease or not to grease?? That is the question."
Large motor frames aways seemed to have a grease passage into the bearing seat area. However, the mfg would only install a zerk if the motor had open bearings (common in motors 40 years ago). Later, as sealed bearings became common, they put plugs in the threaded openings.
Over time many/most of the navy motors went into for cleaning and overhaul. Sealed bearing replaced any open bearings still installed and the service facility pluged the grease passage to prevent damage to the sealed bearing and motor by pumping in grease.
However, the maintanance cards still called for greasing the motor every year or so. So the sailor would reinstall the grease zerks and fill the motor with much un-needed grease.
Bottom line, most large frame motors will have grease passage, however the only way to determine if it has open bearings would be to pull the need bells and see what type of bearing it has. No need to remove the bearing since you should be able to see the seal on the exposed side of the bearing.
Reply to
Steve
As stated care must be taken to not over grease. I have seen recommendations to remove the pipe plug opposite the grease fitting to allow the excess to get out.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
If the motor has zerks, it should have drain plugs on the bottom of the bearing housings. You should remove the drain plugs and pump in a good quality grease thru the zerks until you get some out flow from the drains. Leaving the drains open, start the motor and run until the bearing housing temp stabilizes. Some additional grease will flow out. Then you can plug the drains. You are now set for several years of operation if the bearings are good.
The above assumes your motors have internal bearing caps that close off the bearing cavities from the stator housing. They prevent grease from getting into the rotor/stator area if the drains are open during lubrication. Cheap motors usually do not have caps or zerks. YMMV.
Randy
Reply to
R. O'Brian
There is no simple answer, here. The manufacturer installed a zerk on the open side of the sealed or shielded bearing and expected you to grease it. Subsequently, many of these bearings have been replaced by prelubricated shielded or sealed bearings (both sides).
Save these old motors. They were designed to run cooler than modern motors, since the wire varnish was much inferior to that available today. New bearings and a rewind yields a much more reliable motor than any available using today's engineering specs. They may cost a few more pennies to run, however....
Reply to
Gene Kearns
the open side of the sealed or shielded bearing and expected you to grease it.<
Around 1984 at the company I worked at someone in Service or Engineering contacted Lincoln Motors engineering dept. and asked exactly how much grease to pump into their motors (in response to a customer's question about the lack of information in the literature received with their motor) and was told the only reason the zerks were there was because the bearings were lubricated after installation in the factory and it was cheaper to leave the zerks in than replace them with plugs.
Damn dumb long sentence; sorry.
They recommended never lubricating. Ten years X 5 days a week X 8 hours a day of moderate use would be the average service life of the 1 1/2 to 5 horsepower motors we were using at the time. The problems that arose were generally with the insulation, not the bearings.
dennis in nca
Reply to
rigger
Ain't no big deal to replace greased bearings with permanently lubed or even sealed ones. What you don't want is grease on the motor windings. If you split the motor then while you are in there clean everything up and dress the start contacts too. I never got around to spraying a coat of winding varnish on any of my refurbish jobs but I hear it's not a bad idea. Setting new bearings on 60-100 w light bulbs to expand them works well for cheap. Half of what I know I learned picking brains in this newsgroup.
Reply to
bamboo
We used to grease MG sets, while running, just once a year, and listen VERY carefully as you pump for the SLIGHTEST noise change. That's enough.
Brian Lawson, Bothwell, Ontario.
Reply to
Brian Lawson
Well, 100% of the responders indicated the zerk fittings are for grease, no votes for oil.
I am very pleased with the performance of my latest $20 7.5 hp motor. I scrounged it awhile back dirt cheap because it had a badge on it that said it was a 50Hz motor and the seller thought you couldn't use it on 60Hz power. I told him, but he didn't believe me and laughed at me. I figured I'd done enough to meet a reasonable moral standard and bought it. It runs amazingly quiet and smoothly for a 3450 rpm motor. (By the way, after I got it home I discovered it has another nameplate for 60Hz power, it's simply one rated for either.)
It replaced the one which came off the old 16" chop saw I'm rebuilding. That motor had the worst bearings I've ever heard. I put new spindle bearings in the saw too, and the reduction in noise when spun up and not cutting is simply enormous. I'm going to tear down the old motor and see what kind of bearings are in it. I suspect they're open sided ball bearings, but they might be sleeve bearings, which are said to run quieter.
I'm having fun rebuilding this old chop saw. I'll see how it works for me and if I like it I'll keep it, else I'll either sell it or donate it to the local welding school.
GWE
Reply to
Grant Erwin
At work there was a motor generator and the motor ( GE ) had Zerk fitting. As I remember GE recommended greasing every three years if the motor was run 16 hours a day , five days a week. Otherwise they recommended every ten years.
Naturally this motor was run only a couple of hours / month and the PM called for annual greasing. There was no way to schedule the greasing less often than annually.
Dan
Reply to
dcaster
Put a sticker by each fitting "Grease only if the year ends in 5" Gerry :-)} London, Canada
Reply to
Gerald Miller

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