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Deck Air Turbulance

Discussion in 'Lawn Mowing' started by Smithers, Aug 4, 2005.

  1. Smithers

    Smithers LawnSite Silver Member
    Posts: 2,265

    i have been using double blades for the past 2 months.

    The other day i went back to single, wavy blades. Today i cut 3 lawns. the first two went normal. At the start of the last one i noticed that my ears were hearing loud, thundering noise coming thru the seat and the machine.

    I always have earplugs AND ear muffs, so i thought that the earmuffs are going bad and needed a new pair.

    Reduced the lever for the RPM halfway and the noise was still there...but of course not as loud.

    The only way to make it stop was when i turned the blades off once i was done. i did not see problems with the cut at all..

    it sounded like a sheet of thin aluminum during a storm.

    could one blade be loose? it was too late and did not check under the deck. i always use a torque wrench when changing blades.

    The noise seemed to hit the right frequency and was umbearable even with the hearing protection i had on.

    any ideas?

    the mower has exactly 100 hrs. i am a part timer.
  2. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    Could be an out of balance blade. I have a set of blades I need to get balanced, I know this because all other baldes seem to turn quietly on the machine but this one set, or one in the set, causes this pulsating noise and vibration.
  3. LightningLawns

    LightningLawns LawnSite Senior Member
    Posts: 279

    usually with a loose blade the spindle will spin but the blade will not, leaving an uncut path of grass. Maybe you have something stuck under your deck.
  4. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    Running doubles adds a lot of stress to the spindles, you might have a worn bearing or more.
  5. grassmanvt

    grassmanvt LawnSite Senior Member
    Posts: 906

    I've had a couple spindle bearings go even with low hours. It does make a louder than normal noise although maybe not as bad as you are describing and usually goes gradually. After checking blade tightness, grab the edge of the blade and try to wiggle up and down, any play there might mean a bad bearing. I've also had a baffle come unwelded which makes a lot of assorted noise, maybe just a little part of a weld on one has come undone, causing it to flutter when under all the turbulence of the spinning blades. I'm no mechanic but just a few of my prior experiences.Oh, just thought of something else, check on top of the deck for any obstructions or maybe a belt that has a piece of shrapnall rubbing on it, a loose pulley, etc.
  6. Smithers

    Smithers LawnSite Silver Member
    Posts: 2,265

    yeah, i will check. i dont think it's a loose/bad bearing because it does not shake or wiggle. i just makes this aweful noise.

    it sounds like you are filling up a steel silo with water and you are listening thru the fill hole and catching all the echo. it almost hurts the ear drums.

    i have to cut 3 more tonight. will check under the deck and try the blades....hope it goes away.

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