Shear Bolts Work!

Discussion in 'Lawn Mowing' started by MOturkey, Sep 15, 2009.

  1. MOturkey

    MOturkey LawnSite Silver Member
    Messages: 2,774

    I posted a question about the shear bolts and shear pins on my Walker last week. Turf Dawg and Ed2hess both cautioned against overtightening the shear bolts on the blade hub, so I was careful when I changed out the blades the next time.

    Mowing my neighbor's yard on Saturday afternoon, I sheared the pin in the driveshaft when I ran over some debris he had thrown alongside his garden. Thought for sure the gearbox had gone, as it didn't quit all once, but made a racket, then stopped. I released the blade clutch, then restarted it, and after a few seconds, she let go completely.

    The very next day, I'm mowing the ditch at one of our accounts, when I ran over a piece of automobile tailpipe about 10 inches long. Didn't see it at all in the grass. The blades crimped it, and cut out a piece about 4 x 2 inches. I went ahead and mowed another yard with it after that. The next day, when changing out the blades, which, by the way, were heavily damaged, going to have to remove about 3/8 inch material to get the edge even again, I was surprised that all 4 shear bolts were completely gone. Guess there is still enough friction between the blade nut and hub to keep the blades turning.

    If I had overtightened these, I might be looking at a new gearbox. Bouight a cheap torque wrench, and figure I probably only had them tightened to perhaps 40 ft. lbs,

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