The All New Power Transmission Engineering Blog!

Happy New Year! I am pleased to announce that I will be your new blog writer for PTE. If we haven’t been introduced, my name is Norm Parker and I have been a fairly regular contributor to PTE over the past year and I am looking forward to adding this new role for 2015.

My background is in roller bearings where I have spent time in all types of bearings—ranging from heavy industrial to automotive. I am currently the technical specialist for driveline bearings at General Motors, located at the company’s main Proving Grounds in Milford, MI. While my job is exciting, it probably goes without saying, I can’t talk about it—for the most part.

Though my career is focused around automotive bearings, I have interests in a wide variety of engineering subjects. Along with enjoying all types of transportation, I have been immersed in sealing, elastomers, plastics, powdered metal, gears, castings, housings. I enjoy it all.

I enjoy as well the economics, politics, people and drama that go along with these industries. When I’m visiting suppliers, at least half of our time is spent telling old stories, future outlook and keeping up with the substantial gossip pool around town.

As far as the blog is concerned, we’ll try to keep it on the technical side. This is by no means a forum for me to listen to myself talk.

So, I need your help!

We can talk about why the TI-92 is still the best calculator ever made; why computers have been getting slower since Windows 98 (I assume it’s not just me getting faster); the fact that Dale Jr. is NEVER going to win a championship; 400 ton mining trucks; why my Dad thinks people never landed on the moon. Whatever—I’m game.

I am definitely open to discussing business, politics, global events and economies that affect our businesses—such as oil prices repeating the 2008 crash pattern—which really makes me nervous.

I’m halfway decent on the computer, so we can talk tip/tricks/how-to. We can also talk about serious work stuff too, questions, problems, solutions. But it is a blog, and so if it gets too deep, we’ll throw it into a regular article.

We’ll share some fun tips too. Like, if a co-worker steps away from their computer, hit their Ctrl+Alt+down arrow. (I’ll include the fix with my next post.)

Ok—there you go. While I’m busy doing the only things there are to do in a Michigan winter—work and not freeze to death—send me some topics you would like to discuss or a question you’d like answered.

I look forward to hearing from you!

About Author

Norm Parker

Norm Parker is currently the global senior specialist - roller bearings at FCA US LLC. With his bachelor and master degrees in mechanical engineering from Oakland University (Rochester, Michigan), Parker has developed a keen interest in the academic, commercial and engineering aspects of the bearing industry. Prior to joining FCA, he rose through the ranks of traditional bearing companies and served as bearing technical specialist for the driveline division at General Motors. He is a regular contributor to Power Transmission Engineering Magazine, appearing often in the publication’s popular Ask the Expert feature, as well as authoring a number of bearings-oriented feature articles and The Bearing Blog. The views expressed in this blog are Parker's personal views and they do not represent the views or opinions of FCA in any way.


  1. Peter Schroth
    Peter Schroth 13 January, 2015, 15:17


    What ever became of the idea of a hollow roller in a Roller Bearing? I believe Kaydon sold some for a while. I think the idea was you could preload the rollers better because they were hollow. Do you know of any application where they still use this idea?

    Peter Schroth

    Reply this comment
    • John Lieber
      John Lieber 13 January, 2015, 16:59

      Here is an analysis done in India on the hollow CRB. The idea is to reduce the roller weight to accept higher speeds in machine tool applications.
      EDAC Techonolgies in CT specializes in these.

      Reply this comment
    • Norm Parker
      Norm Parker 14 January, 2015, 20:27

      Hi Peter,
      Thanks for the questions. John, thanks for the reply as well.
      The type of hollow roller that John has the link too is designed primarily for mass savings. They can’t handle much load and have fairly limited use. The more mainstream use of the hollow roller involves a pin-type cage which is still very much used in heavy industry. These are available in cylindrical and tapered versions, thought the overwhelming majority are tapered roller bearings. In these bearings, the cage bar is through the center of the roller. The benefit in doing this is that you can bring the rollers much closer together than with a typical stamped or welded cage, nearly creating a full compliment type tapered roller bearing. This will allow for larger and / or more rollers which will increase the load rating.
      Intuitively, the drawback is the potential for crushing the roller under severe loads (it has happened). That is why this type of bearing is mostly reserved for large bearings where the roller diameter to hole diameter is greater than it would be for smaller bearings.
      In the situation where the applied load is substantial but shock loading is limited, pin-type cages are still a decent selection.

      Reply this comment
  2. Robert Errichello
    Robert Errichello 13 January, 2015, 15:19

    Please describe Heathcote slip and what types of rolling element bearings it occurs in.
    Bob Errichello

    Reply this comment
    • Norm Parker
      Norm Parker 14 January, 2015, 21:01

      Hi Bob,
      Great question! Heathcote slip is the slipping of surfaces that occurs when a spherical surface is rolling on a surface of a different radius. Just about every bearing has some amount of slip on the surface. Even bearings that have seemingly flat surfaces, such as tapers and cylindricals, will still have some slip due to the crowning of the raceways. However, the bearing most associated with substantial slip is the spherical roller bearing.
      When I’m demonstrating this in person, I start with a foam cup. Just roll the cup along the table and it obviously rolls in a circle due to the different diameters of the top and bottom. Now, with your hands, force the cup to roll in a straight line. Both the large and small ends cannot roll at the same time, one side is sliding or spinning. If you roll the cup in a straight line and force the large end to roll, the small side has to slide to keep up. On the other hand, if you force the small end to roll, the large end has to spin faster than the table. Now, if you pick a spot in the center of the cup to roll, the small end slides a little and the large end spins a little.
      Now imagine taking a second cup and placing it large end to large end with the first cup. You have something that looks like a barrel, not too unlike a spherical roller. If you take that barrel and were to bend the table up slightly so that both cups could touch at the same time, the same spinning and slipping situation occurs, just mirrored from one side to the other. So taking the lesson from the single cup, if you force the barreled cup to roll straight from the centers of the cups, you should have 2 direct rolling paths, one on each cup with a spinning section in the center and sliding sections on the outside. This is exactly what happens in a spherical and noted as the Heathcote slip. Much of the newer technology in spherical bearings involves trying to control that slip and determining if the slip or spin is more damaging to the life of the bearing and how to mitigate the effects and losses.
      Have a great day!

      Reply this comment
  3. Elliot Wilson
    Elliot Wilson 13 January, 2015, 17:18

    Congratulations on the blog! I look forward to reading your content, and growing in my understanding in numerous power transmission product categories. Should you have any interest in collaborating with a fellow power transmission, flexible coupling focused, blogger (… holler. Best regards & best wishes!

    Reply this comment

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