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Trying to decypher presicion taperered roller bearing classifications

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  • Trying to decypher presicion taperered roller bearing classifications

    Hi -
    I'm looking over the tapered roller bearings in my old Raglan 5" lathe (England). There's a bit of a mystery here - at least for me.

    The manual for the machine clearly states that the bearings are "Timken bearings of precision 5 class". However, the Timken website and documentation classifies tapered roller bearings in precision classes as 3,0,00,and 000.

    What's going on here? Did the classification systems change in the last 50 years or so since this lathe was made, are there different ways of doing things in England than North America (insert smirk here) or what ? In any case, is there someone out there that can give me an idea as to what precision class of Timken bearings in the 3,0,00,000 system would translate to the "precision class 5 of around 1964" ?

    Looking carefully at the cups that are installed in the headstock reveals not much more info for me to go on, but here's a pic anyway. The only thing that I am not sure about is that little "L1" or "LI" near the top of the bearing. Maybe someone can enlighten me on that too.

    Thanks !!!

    Last edited by LHC; 03-20-2014, 09:11 AM.

  • #2
    There have been big changes in bearing specifications in just the last 20 years. Since the early 1930's bearing specifications were determined by the AFBMA (Anti Friction Bearing Manufacturers Association). In 1993 they officially changed their name to the American Bearing Manufacturers Association. They publish a guide every year outlining all the classifications, what they meant and how to interpret them. Each bearing has a series of numbers and letters on the inner and outer races to identify the specifics. I use a series of manuals entitled "International Cyclopedia Bearing Manual" to decipher the number and lettering system of bearings manufactured before the ISO Standards. It's still available in DVD format, but it's expensive at $195.00 per copy.

    http://www.bhqexpress.com/CGI-BIN/LA...FD8052+M50+ENG


    Since ISO has been around there have been hundreds of changes in the terminology used to identify bearings. While many of the same standards still apply there's a whole new way to identify them. Here's a link to some of the specification catalogs available from ISO.

    http://www.iso.org/iso/iso_catalogue...m?commid=45544

    Here's a link to a catalog by Timken. There's a section on how to interpret the numbering and lettering system.

    http://www.timken.com/en-us/products...tion_Guide.pdf

    Comment


    • #3
      Unlike BALL bearings, which have precision specs that rise with the increase in class number ( 5,7,9)
      ROLLER bearings use lower numbers sequences for the improved relationship (#3, #0 #00),.
      I do not see a copper dot on your outer race. That tells me it is not a precision bearing as the dot shows the maximum eccentricity of a precision ground race
      and is used on "precision class" bearings. (# 3 and lower )
      A class 5 tapered roller bearing while precise, is not considered a "precision" version
      My 1976 manual states that the "L" designation signifies "Light Series" and also " not interchangeable cups and cones with others in this series"
      Also it states the cup and cone come wired together. Precision bearings also come wired together.
      It is generally known that a certain cup can be mated with multiple cones to allow various shaft sizes to be used, or different widths.
      The significance of the wire in this case means the cup and cone ( L )were designed as a single application

      Rich


      A class 5 Timken is not a precision bearing as you would expect
      Green Bay, WI

      Comment


      • #4
        Originally posted by Rich Carlstedt View Post
        Unlike BALL bearings, which have precision specs that rise with the increase in class number ( 5,7,9)
        ROLLER bearings use lower numbers sequences for the improved relationship (#3, #0 #00),.
        I do not see a copper dot on your outer race. That tells me it is not a precision bearing as the dot shows the maximum eccentricity of a precision ground race
        and is used on "precision class" bearings. (# 3 and lower )
        A class 5 tapered roller bearing while precise, is not considered a "precision" version
        My 1976 manual states that the "L" designation signifies "Light Series" and also " not interchangeable cups and cones with others in this series"
        Also it states the cup and cone come wired together. Precision bearings also come wired together.
        It is generally known that a certain cup can be mated with multiple cones to allow various shaft sizes to be used, or different widths.
        The significance of the wire in this case means the cup and cone ( L )were designed as a single application

        Rich


        A class 5 Timken is not a precision bearing as you would expect
        Rich - thanks for the info. This news is actually good in a twisted sort of way - it means that I can get away with spending less money if/when I ever need to replace the bearings - always high on the list with a newbie/hobbiest fellow

        I had read about that copper dot business in my digging around the net and was looking for it myself, but as you say it does not seem to be there. I did check both cups for it.

        Any idea on the second character after the "L" ? It's either a 1 or an I as best I can tell.

        Also - do you have any idea from your documents how the class 5 roller bearing translates to a class in today's grading system for tapered roller bearings? Is there only one "non-precision" grade for these bearings once you leave the #3,#0,#00,#000 precision group?

        For what it's worth, if it helps - the cone is spec'd as 16150 and the cup as 16284B

        Thanks for the info and also thanks to projectnut for those links.

        Cheers,
        Lewis

        Comment


        • #5
          No "1" marks are listed, nor is the letter "I " used in the symbols
          There is a "LL" listed as " Light-Light Series"

          They do say that when the bearing is used for a specific industrial purpose ((special considerations)
          that:
          "To be certain future cup and cone replacements are made correctly, the factory supplement's imprinted identifications with electric penciling to add prefixes and suffixes to the Imprinted part numbers.
          These additional part numbers become important to the user for proper bearing identification and replacement. Make it a habit to ask:" Are there any electric pencil markings on the cup ond cone ? "

          The above of course is addressed to a sales person using the manual

          Rich

          Almost forgot
          The "B" Suffix is listed as a Flanged Cup
          Green Bay, WI

          Comment


          • #6
            Interesting. Yes, they are indeed flanged cups.
            With your info and some additional that I have gleaned from a yahoo user group on these lathes, I'm getting a clearer picture. Still would like to know how the spec that was called up in the manual compares to today's classifications though. I fired off an email with the questions to the big guys themselves (Timken) - if I get an answer back I'll post the results.

            From the user group, I got this info to chew on as well. Is he correct when he says that the difference between the precision bearings is really only the amount of inspection that the units are subjected to? This sounds sort of like electronics parts that are qualified for wider temperature ranges - really only a function of statistical sampling of the batch that are produced and no real "value added" stuff to the part itself.

            from the yahoo user group -

            "one of my friends was strapped for cash so we fitted automobile grade Raglan bearings and for ten years it turns to 0.001of an inch over 20 inches, I am told that the only difference from precision and lower grades is the limit of tolerence that Timken give it when inspection is done."




            Originally posted by Rich Carlstedt View Post
            No "1" marks are listed, nor is the letter "I " used in the symbols
            There is a "LL" listed as " Light-Light Series"

            They do say that when the bearing is used for a specific industrial purpose ((special considerations)
            that:
            "To be certain future cup and cone replacements are made correctly, the factory supplement's imprinted identifications with electric penciling to add prefixes and suffixes to the Imprinted part numbers.
            These additional part numbers become important to the user for proper bearing identification and replacement. Make it a habit to ask:" Are there any electric pencil markings on the cup ond cone ? "

            The above of course is addressed to a sales person using the manual

            Rich

            Almost forgot
            The "B" Suffix is listed as a Flanged Cup

            Comment


            • #7
              One way to look at precision/accuracy classes is that a lower class MAY or MAY NOT be as good as desired but a higher class is inspected and guaranteed to be so. Anything with a +/- >001" tolerance could be within .0001" of the correct size. Some things, however, do get different or additional manufacturing processes to provide the 'better' product and I would think that would apply to bearings.
              Last edited by Don Young; 03-20-2014, 11:20 PM.
              Don Young

              Comment


              • #8
                Back again - I got a response from Timken and thought I'd pass the info along here to sort of "round out" the discussion.

                ----------------------------
                The “Timken Precision 5” (actually 50000) Class 0 is no longer available. We only have the 30000, Class 3 available. You would order (through one of our distributors) a 16150-30000, and 16284B-30000.
                ----------------------------

                He also included a few attachments, one of which refers to codes and class.

                A bit of digging on the Timken site and I found the 800+ page tapered roller bearing manual that shows the radial runout of classes -
                Comparing, it appears the standard class has a radial runout of .0015-.002 specified (i.e. classes 4 and 2)
                The lowest precision grade - 3 - has a radial runout of .0003 - five times better.
                Jumping up to the grade 0 which is no longer available, you gain only 1.5 tenths on the radial runout at a spec of .00015

                Pricing ? well - you pay for precision. Amazon actually lists both the standard and the class 3 bearings - for a set for my lathe (2 cups and 2 cones) it jumps from about 200 bucks for a standard grade to 1200 for a class 3 precision grade.

                Cheers,
                Lewis

                Comment

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