Question about Craftsman 24 Hp 48" Deck Yard Tractor

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The deck belt keeps falling off of my Troy-Bilt 14AT809H766 Horse riding lawn mower. Why? How do I fix it?

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Either the belt is stretched out and needs to be replaced or there is an idler/tensioner pulley that may be weak and not putting enough pressure on the belt.

Posted on Jun 30, 2010

  • jnicklay Jun 30, 2010

    I have replaced the belt three times this year alone. How would a idler/tensioner pulley come lose or not put enough pressure on the belt?

  • Nate Stansfield
    Nate Stansfield Jun 30, 2010

    The tensioner had a rubber piece between it and the deck that acts like a heavy spring to provide pressure.
    On the lowest cutting height, the angle
    from the PTO pulley to the deck pulley is the greatest, which could hurt
    the belt alignment enough to throw the belt off.

    Just to eliminate another possibility for
    why the belt "could" be prone to jumping off (derailing). Park the
    machine on a smooth, even surface (like concrete or asphalt). Set the
    cutting height to the position where you mow most often (this is where
    the belt jumps, right?). Now try to get into a viewing position where
    you can see the leading edge (front) of the deck AND the belt. Does the
    leading edge of the deck appear to be lower than the trailing edge
    (rear)? A ruler, tape measure or other means can reveal whether the
    leading edge is lower than the trailing edge if it is difficult to tell
    with eye sight only. Does the belt from the PTO pulley appear to "bend"
    downward toward the deck as it exits the PTO pulley? If the answer to
    either questions is YES, this is probably why the belt is so wont to
    "get out of the groove". If the deck can be adjusted so the leading
    edge of the deck is SLIGHTLY higher than the trailing edge, you may be
    able to correct the problem. I am not familiar with this machine nor how
    the deck hanging and adjustment hardware is configured. I am trying to
    offer a "geometric" reason why this could possibly occur on a few
    machines and not the entire production run. My personal opinion of how a
    deck "should be angled" is to have the leading edge about 1/8 inch
    higher than the trailing edge. If the deck rides on guage wheels
    entirely, it could be that certain parts of your mowing domain have
    small "swales" or depressions that allow the deck to drop even further
    down when traversing one of those places. The increased angle when (if)
    this happens, might aggravate the tendency for the belt to derail.



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