Does anybody know if alternator manufacturers are starting to use synthetic grease in their bearings? Seems like some of the alternators with lifetime warranties should, but does anybody know for sure? Autolite claims they have "proprietary" bearings in their alternators, but I don't know what that really means.
Alternator Bearings with Synthetic Grease
- Thread starter TxGreaseMonkey
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chevron claims their SRI grease is factory fill on a majority of bearings, it's polyurea, which is good for use around eletrical.
autolite's proprietary bearings are probably the cheapest ones they can get from china. it does sound really good though.
autolite's proprietary bearings are probably the cheapest ones they can get from china. it does sound really good though.
I read about the Chevron SRI grease, you mentioned, and you are probably correct. I wonder if Amsoil's Multi Purpose grease would be even better. Years ago, I would rebuild alternators and use Quaker State high temperature bearing grease. It worked great. I'm looking at replacing an alternator on a 2000 Taurus, with a Duratec engine (67,000 miles). New Motorcrafts are $328--pretty steep for an alternator. Labor will be $200. Together, that's pretty high for replacing an alternator. Hence, the thought about what grease OEMs use.
tom slick, Amsoil's Technical Dept. told me the reason it's not desirable to use anything but a polyurea grease in alternator bearings is because of fire hazzard. If a bearing was over-greased, it could catch fire if you didn't use a polyurea based grease. Therefore, Amsoil does not recommend any of their greases for this application. Interesting.
Huh?
Fire point and Flash point are primarily related to the BASE fluid used in the grease.
Thickener has not much effect at least as far as a polyurea vs a lithium for instance, sounds like Amsoil is just worried about any Liability.
bruce
Fire point and Flash point are primarily related to the BASE fluid used in the grease.
Thickener has not much effect at least as far as a polyurea vs a lithium for instance, sounds like Amsoil is just worried about any Liability.
bruce
It may be due to the fact that polyurea isn't very oily when it leaks out. it tends to dry up quickly.
one of the main causes of electric motor failure is overgreasing.
one of the main causes of electric motor failure is overgreasing.
Kestas
Staff member
I believe one factor of grease usage around electric motors is migration. It'll creep along the surfaces where it can mess up the brushes. You wan't to pick a grease that doesn't migrate.
In one plant that I service, the policy for motor lubrication is this:
All electrical motors are lubricated with polyurea greease (Chevron SRI or equivelent)according to the precise method spelled out by the motor mfg. Some motors will have evacuation plugs that need to be removed for lubrication service, others do not. Some motors need to be running when serviced, others are to be stopped.
It is imperative that we follow the exact mfg recommendations of lubriaction method for all motors.
This particular plant also has a policy of not lubricating ANY fractional motor (less than 1HP).
Collective data has shown that the failure rate for fractional motors that have been serviced is far greater than that of those size motors left alone and allowed to run full term with factory fill.
Many items can withstand a variation of a lube schedule, including product and method. However, motors are not very accepting of other than precision, as prescribed by the mfg.
All electrical motors are lubricated with polyurea greease (Chevron SRI or equivelent)according to the precise method spelled out by the motor mfg. Some motors will have evacuation plugs that need to be removed for lubrication service, others do not. Some motors need to be running when serviced, others are to be stopped.
It is imperative that we follow the exact mfg recommendations of lubriaction method for all motors.
This particular plant also has a policy of not lubricating ANY fractional motor (less than 1HP).
Collective data has shown that the failure rate for fractional motors that have been serviced is far greater than that of those size motors left alone and allowed to run full term with factory fill.
Many items can withstand a variation of a lube schedule, including product and method. However, motors are not very accepting of other than precision, as prescribed by the mfg.
Kestas
Staff member
I'm curious - what is the failure mode for those fractional motors that have been seviced, and for those motors that haven't been serviced?
A fractional motor that is placed into service, and assuming it was engineered properly for that application, has a very low failure rate. In fact, most small motors will run for years and years with no service.
Now, if the motor can be serviced, the risk of overgreasing and causing a leakage that could foul the windings is great. Too great to risk shutting down any sort of production for a motor that can be replaced for very little money during a maintenance downtime. And it is normally the run time after a maintenance downtime that the overgreased motor shows itself. Very costly to shut down production for such an event.
Would you take apart and lubricate the motor on your furnace fan? Knowing that you may well cause a problem, or are you going to let it run and hope for the best, knowing they have a long running track record?
Bigger motors are another thing. Their cost alone warrants a good lubrication schedule.
Now, if the motor can be serviced, the risk of overgreasing and causing a leakage that could foul the windings is great. Too great to risk shutting down any sort of production for a motor that can be replaced for very little money during a maintenance downtime. And it is normally the run time after a maintenance downtime that the overgreased motor shows itself. Very costly to shut down production for such an event.
Would you take apart and lubricate the motor on your furnace fan? Knowing that you may well cause a problem, or are you going to let it run and hope for the best, knowing they have a long running track record?
Bigger motors are another thing. Their cost alone warrants a good lubrication schedule.
another way to look at it is if you could easily spend $150 in labor (during it's lifespan) to maintain a fractional hp motor that costs $100, only to extend the lifespan a tiny amount. 30 minutes of labor and a $100 motor swapped in might be cheaper.
I find motor windings to be the main cause of failure in the motors I maintain. the last one I replaced had shorted a winding to it's case. it was a TEFC with no grease fittings, it's bearings were in great shape after 10 years of service.
I find motor windings to be the main cause of failure in the motors I maintain. the last one I replaced had shorted a winding to it's case. it was a TEFC with no grease fittings, it's bearings were in great shape after 10 years of service.
MolaKule
Staff member
Loooks like Mobil makes one as well:
http://www.exxon.com/USA-English/Lubes/PDS/NAUSE2GRSEXPolyrex_EP_2.asp?
here is the pdf file for Synchroflow's letter on greasing electric motors:
http://www.syncroflo.com/support/greaserec.pdf
and from Amsted Rail Group:
http://arg.birkey.com/tech_sheets/9501.asp
Electric Motors:
http://www.leeson.com/products/techref/maintenance.htm
Certification Marks on Greases from the NLGI:
http://www.nlgi.com/certification_list.htm
Chevron's Grease:
http://www.ottsen.com/pages/chgrs/rykotac.html
An article from Machinery Lubrication:
http://www.machinerylubrication.com/article_detail.asp?articleid=817
[ February 09, 2006, 01:51 PM: Message edited by: MolaKule ]
http://www.exxon.com/USA-English/Lubes/PDS/NAUSE2GRSEXPolyrex_EP_2.asp?
here is the pdf file for Synchroflow's letter on greasing electric motors:
http://www.syncroflo.com/support/greaserec.pdf
and from Amsted Rail Group:
http://arg.birkey.com/tech_sheets/9501.asp
Electric Motors:
http://www.leeson.com/products/techref/maintenance.htm
Certification Marks on Greases from the NLGI:
http://www.nlgi.com/certification_list.htm
Chevron's Grease:
http://www.ottsen.com/pages/chgrs/rykotac.html
An article from Machinery Lubrication:
http://www.machinerylubrication.com/article_detail.asp?articleid=817
[ February 09, 2006, 01:51 PM: Message edited by: MolaKule ]
MolaKule
Staff member
So many greases have high levels of Sulfur-Phosphorus additives in them for EP service and these adds, if not accompanied by metal deactivators, can leak onto the insulation AND copper windings and corrode them.
Very few AC induction motors uses brushes these days, as AC induction motors use start and run capacitors. Most brush type motors are series wound and are found in DC motors such as for drills.
Most high-end polyurea grease have high oil retention (in a jelled state), moderate levels of EP additives, and use high viscosity synthetic oils such as esters for lubricity.
Nissan uses a polyurea grease for their front wheel bearings.
Nye lubricants make excellent synthetic polyurea greases.
Great links, MolaKule!
Bear in mind, folks that the maintenance procedure provided by one motor mfg may differ from that of another mfg.
(some rec. motor at stop measureing precise amounts, other rec. purging old grease out evacuation plug and then run motor with plug out, etc...)
Many have found this out the hard way by following only one mfgs rec. for all motors.
Be certain to check the mfg recommendations for each brand and type of motor.
Bear in mind, folks that the maintenance procedure provided by one motor mfg may differ from that of another mfg.
(some rec. motor at stop measureing precise amounts, other rec. purging old grease out evacuation plug and then run motor with plug out, etc...)
Many have found this out the hard way by following only one mfgs rec. for all motors.
Be certain to check the mfg recommendations for each brand and type of motor.
Sorry to drag this one up from the vault (was searching for something else...)
Anyway, interesting thoughts on greases used for alt bearings.
A FWIW is that in one of our diesel vehicles the rear alternator bearing is a very small INA needle roller that runs directly on the shaft. (appears to use a hardened, pressed on and non-replaceable sleeve...)
It also sits pretty closely to the turbine and dump pipe side of a turbocharger.
Surprisingly, the OE grease dies prematurely with the bearing soon after. (Magneti-Marelli
)
The trick is to re-grease the needle roller periodically.
When I first did it four or so years ago, I used some Neo Z12 grease I had, which is some sort of syn base oil with a Li complex thickener.
Never had a problem with it.
Six months ago when the front bearing started to die I replaced it and re-greased the rear bearing again with Redline's CV-2.
The brushes, etc seemed to be pretty clean, considering an unshielded bearing was pretty close by.
Anyway, interesting thoughts on greases used for alt bearings.
A FWIW is that in one of our diesel vehicles the rear alternator bearing is a very small INA needle roller that runs directly on the shaft. (appears to use a hardened, pressed on and non-replaceable sleeve...)
It also sits pretty closely to the turbine and dump pipe side of a turbocharger.
Surprisingly, the OE grease dies prematurely with the bearing soon after. (Magneti-Marelli
The trick is to re-grease the needle roller periodically.
When I first did it four or so years ago, I used some Neo Z12 grease I had, which is some sort of syn base oil with a Li complex thickener.
Never had a problem with it.
Six months ago when the front bearing started to die I replaced it and re-greased the rear bearing again with Redline's CV-2.
The brushes, etc seemed to be pretty clean, considering an unshielded bearing was pretty close by.
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