Gravely Belt WB blades spinning fast then slow IDEAS?

Discussion in 'Mechanic and Repair' started by Buddha92SLC, Apr 24, 2008.

  1. Buddha92SLC

    Buddha92SLC LawnSite Member
    Posts: 54

    My old gravely belt drive WB has something happening with the blades. When I engage the pto the blades are spinning but it doesn't seem that they are spinning at their fullest potential. Then today I was mowing a thick lawn, and the blades would slow down almost to a stop where I had to crawl to finish the yard. Is this a belt tension issue? Where else should I look for. it is weird because sometimes the blades sound like they are spinning super fast and other times lagging. Any ideas?
     
  2. Jay Ray

    Jay Ray LawnSite Fanatic
    Posts: 6,510

    It might help if you said whether you have an electric clutch or some manual system of blade engagment.
     
  3. Buddha92SLC

    Buddha92SLC LawnSite Member
    Posts: 54

    Yeah that would help wouldn't it. It is a manual lever that engages the blades. There is a small ball style switch that the bar pushes in to engage the blades. This is a Gravely WB Pro36 from the 80's probably. It's a tank.
     
  4. John Gamba

    John Gamba LawnSite Fanatic
    from ct
    Posts: 10,812

    Is the belt Glazed?? Can you post a pic of the belt where it hits the pully??
     
  5. GravelyNut

    GravelyNut LawnSite Bronze Member
    Posts: 1,594

    Could be that there are worn spots on the belt. Slips when the drive pulley hits that area. Then picks up again when it gets past it. Under no load, the belt gets past the worn area fast enough not to slow down the blade spindle. Belt tension may be weak at those spots also.
     
  6. John Gamba

    John Gamba LawnSite Fanatic
    from ct
    Posts: 10,812


    Lets not forget about warn Pulleys:) They only grab the OUTSIDE of the belts.With older mowers its good to replace the pulleys,belts and Tension mechanisms.


    Dont forget about the Engine pullys :waving:
     
  7. GravelyNut

    GravelyNut LawnSite Bronze Member
    Posts: 1,594

    That is true.:drinkup:
     
  8. John Gamba

    John Gamba LawnSite Fanatic
    from ct
    Posts: 10,812

    I said it wrong. The worn pullys will only grab the "Top" of the side's. Make slip easy:laugh:
     
  9. Buddha92SLC

    Buddha92SLC LawnSite Member
    Posts: 54

    Ok this is strange... today when it happened multiple times I grabbed the pto engagement handle and pulled back ever so slightly. The blades picked back up to full speed instantly. Whenever it happened I pulled back a little on the pto handle and it would kick back up to speed. Strange. I'm going to pull the deck cover off and take a look tomorrow. I'll take pictures. I just replaced every belt on the mower last season. I'm p/t so I think the belt is still good. I only have 10 customers. Any ideas where to look tomorrow with this new information?
     
  10. John Gamba

    John Gamba LawnSite Fanatic
    from ct
    Posts: 10,812



    The tensioner.
     

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