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Thrust bearing on crank,Jerry?

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  • mrikio
    Jerry have you had any issues on the pusher config. on your generac?(I understand you took it apart) I have been reading about the concerns on the Briggs,400lb
    Message 1 of 3 , Jan 8, 2009
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      Jerry
      have you had any issues on the pusher config. on your generac?(I
      understand you took it apart) I have been reading about the concerns
      on the Briggs,400lb pull,but only 50 pushing on the crank. The VW
      thrust bearing is on the REAR of the crank,and that has 4 throws.A lot
      more places to fail. Dont know how that applies,but if the briggs
      crank was cast,I could see that to be a problem.
      Thanks,
      Mark
    • JERRY
      Hi Mark, I haven t done anything yet with the Generac that I took apart, been working on other projects. But I plan to get back to it before long. Not that I
      Message 2 of 3 , Jan 9, 2009
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        Hi Mark,

        I haven't done anything yet with the Generac that I took apart, been
        working on other projects. But I plan to get back to it before long.

        Not that I know much about Briggs, but I would guess that it might
        have a flat, needle thrust bearing like my Kohler. It would only work
        while pulling on the crank from the pto end. I suspect it is that way
        because many of these kind of engines are made in the vertical
        configuration and used for mowers where either the blade or some
        heavy pulley or something is attached and the crank has to carry that
        weight all the time.

        Pushing from the pto end thru the crank to the other end of the
        Generac case is what I have been doing and haven't seen anything to
        be concerned about for wear on the case. But I don't have very many
        hours on it yet, so there could still be a surprise waiting.

        Either the thrust surface in the case wears too fast, which can be
        easily monitored by checking the end-play on the crank. If it does
        get too loose, a needle thrust bearing could probably be installed at
        that end. Kohler told me they have made them that way, and also with
        bearings on both ends.

        Or the crank eventually fails at the rod throw where the force would
        have to be off-set and pass thru the crank pin. But consider maybe
        150 pounds of thrust passing thru it, is that going to be a problem?
        Like I just said above, Kohler can put in a thrust bearing to take
        pushing from the pto end, (or pulling from the flywheel end, which
        does not seem to be a likely possibility they would try to
        accommodate), so that might suggest they think that the crank can take it.

        I have looked a little into an external pre-lubed sealed ball bearing
        on the crank to run against the case just to take the thrust, but so
        far it doesn't work well with my arrangement of the taper-lock
        bushing of my prop flange adapter. I might need to re-think how I did
        the adapter to make it work. The old Hager belt drives on 2-strokes
        used simple pre-lubed sealed ball bearings that took all the thrust,
        and they lasted many hours, so it might work.

        Also in an old post to this group, someone explained that the "cast"
        steel cranks on these v-twin engines are very high quality and
        nothing to worry about. They would be good enough for their many
        possible applications, otherwise Kohler, Briggs, Honda, or Generac
        would soon be out of business from too many failures.

        Jerry Booker


        At 09:16 PM 1/8/2009, you wrote:
        >Jerry
        > have you had any issues on the pusher config. on your generac?(I
        >understand you took it apart) I have been reading about the concerns
        >on the Briggs,400lb pull,but only 50 pushing on the crank. The VW
        >thrust bearing is on the REAR of the crank,and that has 4 throws.A lot
        >more places to fail. Dont know how that applies,but if the briggs
        >crank was cast,I could see that to be a problem.
        >Thanks,
        >Mark
        >
        >
        >------------------------------------
        >
        >
        >### Lets use this list to build a knowledge base for those who are
        >interested in flying with these engines. Don't forget you can search the
        >messages archive for past discussions. Please keep comments on subject.
        >Sorry, no attachments allowed.
        >
        >For access to the home page:
        > >http://groups.yahoo.com/group/Small4-strokeEngines/<
        >
        >For direct access to the files area:
        > >http://groups.yahoo.com/group/Small4-strokeEngines/files/<Yahoo!
        > Groups Links
        >
        >
        >
      • JERRY
        This is a follow-up to my previous message. I just went out to my shop and tested my Generac crankshaft. I set it up vertically on the flywheel, then attached
        Message 3 of 3 , Jan 10, 2009
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          This is a follow-up to my previous message.

          I just went out to my shop and tested my Generac crankshaft. I set it
          up vertically on the flywheel, then attached a dial indicator across
          the gap between the counter weights, opposite the connecting rod pin.
          I then stepped up on the end of the crank and even bounced on it. I
          saw no movement in the dial indicator needle at all, which is
          graduated in 0.001". My bouncing force on the end of the crank would
          have been up around 200 pounds.

          So I'm not going to worry about any distortion of the crankshaft
          across the rod throw, from what might be at most 200 pounds of thrust
          from the direct drive prop.

          Jerry Booker



          At 06:21 PM 1/9/2009, you wrote:
          >Hi Mark,
          >
          >I haven't done anything yet with the Generac that I took apart, been
          >working on other projects. But I plan to get back to it before long.
          >
          >Not that I know much about Briggs, but I would guess that it might
          >have a flat, needle thrust bearing like my Kohler. It would only work
          >while pulling on the crank from the pto end. I suspect it is that way
          >because many of these kind of engines are made in the vertical
          >configuration and used for mowers where either the blade or some
          >heavy pulley or something is attached and the crank has to carry that
          >weight all the time.
          >
          >Pushing from the pto end thru the crank to the other end of the
          >Generac case is what I have been doing and haven't seen anything to
          >be concerned about for wear on the case. But I don't have very many
          >hours on it yet, so there could still be a surprise waiting.
          >
          >Either the thrust surface in the case wears too fast, which can be
          >easily monitored by checking the end-play on the crank. If it does
          >get too loose, a needle thrust bearing could probably be installed at
          >that end. Kohler told me they have made them that way, and also with
          >bearings on both ends.
          >
          >Or the crank eventually fails at the rod throw where the force would
          >have to be off-set and pass thru the crank pin. But consider maybe
          >150 pounds of thrust passing thru it, is that going to be a problem?
          >Like I just said above, Kohler can put in a thrust bearing to take
          >pushing from the pto end, (or pulling from the flywheel end, which
          >does not seem to be a likely possibility they would try to
          >accommodate), so that might suggest they think that the crank can take it.
          >
          >I have looked a little into an external pre-lubed sealed ball bearing
          >on the crank to run against the case just to take the thrust, but so
          >far it doesn't work well with my arrangement of the taper-lock
          >bushing of my prop flange adapter. I might need to re-think how I did
          >the adapter to make it work. The old Hager belt drives on 2-strokes
          >used simple pre-lubed sealed ball bearings that took all the thrust,
          >and they lasted many hours, so it might work.
          >
          >Also in an old post to this group, someone explained that the "cast"
          >steel cranks on these v-twin engines are very high quality and
          >nothing to worry about. They would be good enough for their many
          >possible applications, otherwise Kohler, Briggs, Honda, or Generac
          >would soon be out of business from too many failures.
          >
          >Jerry Booker
          >
          >
          >At 09:16 PM 1/8/2009, you wrote:
          > >Jerry
          > > have you had any issues on the pusher config. on your generac?(I
          > >understand you took it apart) I have been reading about the concerns
          > >on the Briggs,400lb pull,but only 50 pushing on the crank. The VW
          > >thrust bearing is on the REAR of the crank,and that has 4 throws.A lot
          > >more places to fail. Dont know how that applies,but if the briggs
          > >crank was cast,I could see that to be a problem.
          > >Thanks,
          > >Mark
          > >
          > >
          > >------------------------------------
          > >
          > >
          > >### Lets use this list to build a knowledge base for those who are
          > >interested in flying with these engines. Don't forget you can search the
          > >messages archive for past discussions. Please keep comments on subject.
          > >Sorry, no attachments allowed.
          > >
          > >For access to the home page:
          > > >http://groups.yahoo.com/group/Small4-strokeEngines/<
          > >
          > >For direct access to the files area:
          > > >http://groups.yahoo.com/group/Small4-strokeEngines/files/<Yahoo!
          > > Groups Links
          > >
          > >
          > >
          >
          >
          >------------------------------------
          >
          >
          >### Lets use this list to build a knowledge base for those who are
          >interested in flying with these engines. Don't forget you can search the
          >messages archive for past discussions. Please keep comments on subject.
          >Sorry, no attachments allowed.
          >
          >For access to the home page:
          > >http://groups.yahoo.com/group/Small4-strokeEngines/<
          >
          >For direct access to the files area:
          > >http://groups.yahoo.com/group/Small4-strokeEngines/files/<Yahoo!
          > Groups Links
          >
          >
          >
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