Ask the Mechanic

Belt Flip

READER: I have a 350 John Deere rake that runs off the PTO. I like the ease of using the rake around trees because I can pick it up and back under trees. I also like it because I can control the speed of the basket independently of the ground speed the tractor is moving. It drives off a belt, so a gearbox is not needed. However, when I went to the field last year, the belt decided it wanted to try to roll over. I could loosen it and get it straight, but it would immediately flip when I turned on the rake. I used it last year, but I would like to correct the problem this season. Can you tell me what is making the belt flip?

STEVE: The first thing you need to do is make sure your drive sheave and driven sheave are lined up. To do this, take a straight edge and lay it across both sheaves. The straight edge should lay perfectly across both. If it does not, adjust accordingly. If you don't have a straight edge, a string will also work. If the sheaves are aligned, more than likely your larger sheave on the rake is rusty and possibly has debris or "dirt daubers" in the belt groove. The belt is designed to rub on both sides of the sheave and not touch the bottom of it. If the sides of the sheaves are rusty or obstructed, the belt cannot slip down in the sheave easily and will ride up and try to flip. Clean the sheave of debris and dirt, and make sure the sheaves are not worn enough to allow the belt to rub on the bottom of the sheave.


One of the most common accidents on the farm happens when a hot bearing sets a round baler on fire. This is a common problem that cannot only destroy a round baler but also the tractor hooked to it. When the hydraulic hoses catch, the rest is history. One way to help eliminate this problem is to occasionally stop and check the temperature on all bearings with an infrared thermometer -- just like the one they use when you go into a restaurant to check your temperature for COVID. It only takes a few minutes, and the temperature on a failing bearing will be so much higher than the other bearings, it will easily get your attention. It's not how fast you make hay; it's how you make hay fast.


-- Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email


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