Timken Bearings???

Kroll,
several years ago I got a bearing catalog from Bearings Inc. They can get almost any bearing You can use automotive taper bearings. Lathe bearings have much tighter tolerances and they do cost a lot more. Back when I got the catalog, each bearing in the lathe tolerance were about $100.00 each - using memory and getting older.
 
look for the ABEC grade. a higher number indicates the precision.
a ABEC grade 3 is sufficient for electric motors, generally.
most tapered roller bearings(timken) are made to ABEC 7 or ABEC 9.
a cars tapered roller bearings are just as precise as a lathes' headstock bearings, make no mistake grade for grade.

consider the pressures and safety requirements for passenger vehicles or a better example Big Rig Safety requirements.

liability dictates precision in manufacturing, where life and limb are at stake, a 10:1 safety factor is employed sometimes more dependent on industry and intended purpose.
 
ABEC applies to ball bearings. RBEC applies to roller bearings. However, except for the obvious ones (for example, tapered roller bearing cup ID tolerance), the tolerence table figures for the 5 grades are generally the same in both standards.

Robert D.

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nine4gmc,

Could you post a photo of the back of the boxes?

Robert D.
 
We learn something every day,like others I thought that since the numbers were the same the bearings had to be the same.When I google the #'s w/Timkens,Amazon and Auto Zone sold them,so I just could not figure out why Clausing and the site that Richard had posted wanted alot more than others.Now we all know,it made a good subject,thanks for the discussion and the links---kroll
 
There are no records and apparently no corporate memory as to what the dates engraved on the bearings are. But from circumstantial evidence (and a knowledge of how production lines are normally run), I think it safe to say that we have "proved" that the dates are not installation dates. The evidence is that we have more than just two or three recent (last decade or so) examples where the two dates on bearings removed from a single headstock are from several months to more than a year apart. Atlas and Sears in their advertising often claimed that the bearings used were "specially selected". One of the ABEC/RBEC writeups I read yesterday reminded me that for many years after the bearing tolerance standards were written, few if any bearing manufacturing companies made or claimed to make straight from scratch anything higher than ABEC/RBEC 1. As was the practice through the same years with carbon composition resistors, any grade higher than 1 was selected by physical inspection of the production. The selection process continued only until the quota for the higher grades was filled.

So the dates on the bearings must be inspection dates. What we have no clue to is whether the engraving was done after passing inspection by Timken or by Atlas.

Robert D.
 
wa5cab said:
ABEC applies to ball bearings. RBEC applies to roller bearings. However, except for the obvious ones (for example, tapered roller bearing cup ID tolerance), the tolerence table figures for the 5 grades are generally the same in both standards.

Robert D.

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actually RBEC scale is for non tapered roller bearings.

for timken standards are as follows
In ascending order of accuracy,
they are identified in the metric system as Class C/S, B/P, and A,
while in the inch system as Class 3, 0, and 00. they also have a AA and a 000 grade as well
to be correct.
Click to expand...
 
nine4gmc,

Thanks. The back of my boxes look like the back of yours. I.e., the -20024 suffix and the hologram. Mine were drop shipped from a Timken warehouse in KY.

That probably means that they are a lower RBEC grade.

Robert D.
 
Richard,

Edit -

Over the course of the evening, I acquired ANSI/ABMA Standard 19.2, Tapered Roller Bearings-Radial, Inch Design, and ANSI/ABMA Standard 20, Radial Bearings of Ball, Cylindrical Roller and Spherical Roller Types. The final answer is that neither ABEC nor RBEC tolerance classes apply to tapered roller bearings. The Timken Class system goes 3, 0, 00 and 000. In order of increasing precision. The ANSI system goes 4, 2, 3, 0, 00. The only tolerance that is different between 4 and 2 is radial runout.

Allowable radial runout, which is probably both the most significant to us and the easiest one to understand, for the five ANSI classes are, in ten thousandths of an inch, 20, 15, 3, 1.5, .75. I would guess it's a safe bet that the Timken classes mean the same thing as their ANSI matches.

Robert D.

Richard King said:
I just found this info online It shows the smaller the number the more precision. I do know that angular contact ball bearings are different, the higher the number the higher the precision.


http://www.timken.com/en-us/solutions/machinetools/Pages/BearingPrecisionLevels.aspx
Click to expand...
 
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I did a scraping class at Timken several years ago and I was given a tour of the plant in Canton. It was amazing when they showed me the one line of machines where they were grinding the outer cup on a Heald grinders that had to be made in 1940 and they said "the old iron" did a better job then the new machines. We also walked by an area where they were still running leather belts from the ceiling and it was explained that they get a better surface finish with the old 1920's machines as they do not incorporate the vibration of the motor to the spindle . I also saw how they measure the bearings as they come off the grinders and they would mark the TIR (total indicator run-out) and place them in different boxes. They would come off the same machine and some were within .00005" and others were out .0001". If you think about it if the outer race is out .00005" and the ID inner cone, the shaft is probably 2 times less in size the so the TIR tolerance error is immeasurable. This is an interesting thread.

I have been buying Timken bearings for years and have found out you can't just give the bearing house the bearing number, you have to tell them it's for a machine tool. That's why you have to buy machine tool bearings at a well know and established bearing supplier who sells to industry and not order machine tool bearings from a auto parts store. Or the previous owner of your machine bought the bearing at a auto parts store and it is a lower grade bearing. Also when buying bearings, be sure to tell the supplier you want a new bearing. If you receive a Timken bearing in a generic blue box and it says "Bearing" and has a sticker on it saying Timken the odds are it is a re-manufactured bearing. There is a supplier called Baker Bearing that buys over stocked bearings, at auctions of companies who had large tool cribs with bearings and they cleaned them and sell them wholesale to the retail supplier as reconditioned and the retailer sells them to you as new. So if you buy a bearing be sure it comes in a box that is from the manufacturer. Rich
 
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