# correct grease for AC55 front bearing?



## madderscience (Jun 28, 2008)

The Solectria/Azure AC55 has a grease fitting on the front bearing.

Does anybody know what the correct type of grease to use on this is?

(mixing incompatible grease types can cause bad things to happen)

Thanks


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## Ivansgarage (Sep 3, 2011)

I would suggest Yak Fat, made from Yaks.

This is a picture of the famous "YakFat Man" best to avoid his grease!


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## Ivansgarage (Sep 3, 2011)

Have you thought about just replacing the bearing? with a sealed bearing.

Bearings are cheap.........

A primer about grease: It's basically nothing more than a heavy oil mixed with enough soap to make it stringy and clingy enough to remain in place as the bearing spins. This will ensure the bearing's rollers or balls are constantly covered in the oil. The soap is based on a variety of compounds, notably lithium or aluminum complexes for most of the greases used in cars, trucks and boats. 

Problem: Not all the soaps are compatible with each other. This causes the soap and the oil to separate, letting the latter settle to the bottom of the cavity the bearing is in. No surprise—a lot of grease caps have a poor metal-to-metal seal and will let the oil leak out after some weeks. Like yours did. 

Your wheel bearings were probably originally lubed with a lithium-12-complex grease, a perfectly good grease for wheel-bearing use, even on a boat trailer if it’s maintained. Shooting some more grease into the bearing cap with a grease gun isn’t a bad idea. Shooting an incompatible grease in is.

This counterpoints the need to completely remove the last vestiges of old grease from a bearing whenever it's repacked. Yes, you want to remove the dirt and wear particles, but odds are you won't know what kind of grease the last mechanic used.


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## major (Apr 4, 2008)

madderscience said:


> The Solectria/Azure AC55 has a grease fitting on the front bearing.
> 
> Does anybody know what the correct type of grease to use on this is?
> 
> (mixing incompatible grease types can cause bad things to happen)


Is there currently a problem? Without knowing the OEM recommendation and service history you can do more harm than good.



Ivansgarage said:


> Have you thought about just replacing the bearing? with a sealed bearing.


I like this suggestion. Be sure to get a bearing (good quality) which has high temperature seals (not shields) and high temperature grease. Chevron SRI2 or BRB2 are what we've used. 

And you need to properly assemble the new bearing into the motor.

Regards,

major


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## madderscience (Jun 28, 2008)

The motor is currently doing fine, and I want to keep it that way.

If and when I do have to take it apart, I would probably go to a sealed roller bearing (owing to the side load from my belt drive)

Alternatively, yes I could take things apart and clean out all the old grease. 

I was hoping somebody would know what the current type of grease is so that I could add some compatible grease, just to make sure it is full up. This motor came to me surplus. Not many miles, clearly, but certainly sat for years under unknown but probably outdoor conditions. I'm willing to take the chance that odds are nobody has added any grease to it since new.

I did have a bearing failure in the differential pinion recently (other end of the belt system) I attribute this to the worn-out-to-begin-with bearings (junkyard differential) and my overtightening of the pinion bearings as a result of removing and reinstalling the pinion flange without replacing the crush sleeve. The diff has now been rebuilt with a solid pinion spacer eliminating this weakness.


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## piotrsko (Dec 9, 2007)

If the motor is government surplus there will be specification sheets available. Install specs, rebuild specs, build specs, maintenance specs, governments are anal that way. Hopefully your google foo is wise and powerful.


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## electro wrks (Mar 5, 2012)

madderscience said:


> I did have a bearing failure in the differential pinion recently (other end of the belt system) I attribute this to the worn-out-to-begin-with bearings (junkyard differential) and my overtightening of the pinion bearings as a result of removing and reinstalling the pinion flange without replacing the crush sleeve. The diff has now been rebuilt with a solid pinion spacer eliminating this weakness.


One thing my designer's eye caught that might be related to this problem is the excessive amount of overhang (leverage) the sprocket has on the pinion shaft. This is a common problem with the wider toothed belts. The motor sprocket is as close as possible to the motor end housing to limit the overhang force. It should be likewise on the dif pinion shaft. If the bearing fails again, repositioning the sprocket as close as possible to the dif might help. 

If the sprocket will fit over the carriage and ways, it will push the limits of your SB 9 (As I see on your blog-great old lathes-I have one of the same vintage) to counter bore the sprocket to sink it closer to the dif. This assumes the sprocket is not case hardened (or something crazy like that) and machinable. As there's not enough overlap between the mounting holes in the pinion flange and the center hole in the sprocket, an adapter plate will have to be machined. This could be as simple as a large, HD (thick) washer machined to fit. Use the thickness of the pinion flange as a guide as to how thick the adapter needs to be. Of course, this requires the motor and belt positions to be shifted back. I can't tell how much room there is in the frame to do this.

What a great project! I wish I had the resources and time to take on one like it.


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## major (Apr 4, 2008)

madderscience said:


> The Solectria/Azure AC55 has a grease fitting on the front bearing.
> 
> Does anybody know what the correct type of grease to use on this is?
> 
> (mixing incompatible grease types can cause bad things to happen)


Hey madder,

I took a look at your link and the photo of the AC55. Rings a bell. That is the motor from Lincoln Electric Motor Division, 254 frame NEMA. I am pretty sure it used the Lincoln standard DEH and bearing which had the grease fitting. Here is a link to a service manual and copy of section on the bearing grease. http://www.leeson.ca/Downloads/102104 Large Industrial Inst..pdf The text didn't copy and paste, so look it up yourself. No guarantee it is right, but likely IMO. 

major


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## madderscience (Jun 28, 2008)

Thanks major for the Lincoln motor info. That could be very useful.

WRT to electro's comment regarding shaft length and belt positioning, I am aware of the lever force exerted by the tensioned belt on the shafts. On the motor end, the driveR sheave/pulley is about as close to the motor face as it can get. The centerline of the belt is about 2" off the motor face, the belt itself is 1.25" wide. I could get it in another 1/4" without modifying anything, and about 1/2" with some further milling down of the adapter hub. I'm not too worried on that end because the motor shaft is solid 1.25" steel, wider inside the motor, and the rear motor bearing is 15" or so back so will help keep things well aligned. As long as the ball bearing can handle the side load, it should be fine. (The motor took minutes to coast down from 3000 rpm or so when I had the belt off recently, so it is happy for now)

On the diff side, it is a bigger concern. The front and rear pinion bearings on the diff are only about 6" apart. However, they are pre-tension tapered roller bearings, designed to handle considerable side loads (such as what is created by the differential gears themselves as well as the weight of the spinning driveshaft). I have the driveN sheave there about as close to the diff flange as I can get it with the separately milled adapter that fits the sheave to the original driveshaft flange. If I were to modify the flange itself or manufacture a custom one instead of creating an adapter I could get the sheave in another 3/4" to 1", but doing this would require repositioning the motor to keep things in alignment. The diff can't move forward due to wheel position, so the motor would have to move back. There is room to move it back another inch or so but it would take re-welding the mounts for it.

I haven't tried milling the pulley sheaves though I have been tempted to try it to cut out some unneeded weight. I have drilled the driveN sheave to create mounting points for the adapter, that went just fine. I don't think they are hardened, at least not very much.

Thanks for all the feedback.


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