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Using Large Flat Belt Pulleys With V-belts

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by markba633csi, Nov 13, 2016.

  1. markba633csi

    markba633csi United States Active Member Active Member

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    I see this is commonly done on machinery which (I think) was originally run from a master line-shaft system. I'm enclosing a picture of Wildo's 9A restoration as an example; my Diamond mill has a similar setup. How does the belt stay on if the large pulley isn't crowned? Would a serpentine or leather flat belt be a better choice, and the motor pulley changed over to a flat one (with a crown)?
    Mark S. wildos9Adrive1a.jpg
     
  2. Wreck™Wreck

    Wreck™Wreck United States Active User H-M Supporter-Premium

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    The belt is positioned by the driving V-belt sheave, flat belts do not require crowned sheaves, alignment is important however.

    Klaatu barada nikto
     
  3. 12bolts

    12bolts Global Moderator Staff Member Active Member

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    My shaper has a large flat driven pulley. From what I have seen when the 2 pulleys are in close proximity tracking is not a problem as the smaller V pulley keeps it positioned

    cheers Phil
     
  4. markba633csi

    markba633csi United States Active Member Active Member

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    I just wondered cause the v-belt is not really designed to run on its inside surface, but it seems to work anyhow. A simple solution and cheap. The best kind.
    Mark
     
  5. Mister Ed

    Mister Ed United States Active User Active Member

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    This was standard on Logan lathes, for the belt from the motor to the jackshaft. It makes changing pulleys (speeds) very easy with just a little release of tension. I have never seen a tracking or tension issue. Jackshaft to spindle is/was flat belt.
     
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  6. 12bolts

    12bolts Global Moderator Staff Member Active Member

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    I think you will find it mostly occurs when the flat pulley is of a quite large diameter. Consequently the massive surface area of the belt on the large pulley really negates the issue of the v belt running on its inside face

    Cheers Phil
     
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  7. benmychree

    benmychree United States John York H-M Supporter-Premium

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    I beg to differ, flat belts are always run on crowned pulleys. Perhaps you meant to say that in a vee/flat drive, the vee belt does not need to be running on a crowned pulley.
     
  8. benmychree

    benmychree United States John York H-M Supporter-Premium

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    I ran a line shaft in my shop many years ago and used a vee/flat drive with a two grooved sheave on the motor about 4" diameter using belts approximately 7/8" wide running on a 30" diameter pulley on the line shaft that was crowned; the belts nestled up against each other , and it worked fine and slippage was not a problem with a 3HP motor driving.
     
  9. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    my SB11" lathe has a similar drive , the motor pulley has a v pulley- the rest of the drive is done with flat pulleys.
     
  10. Kernbigo

    Kernbigo United States Active User Active Member

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    flat belt pulleys are normally crowned
     

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