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716 Deck drive belt part II


deerhunter

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A Couple weeks back I made a post about going thru a drive belt about 1X per mowing season on my 716H. I received a lot of good suggestions one which stood out was checking the tracking of the belt on the pulleys. I took a look at everything and the thing that I found is that the shaft/rod which goes thru the tractor frame which connects to the idler assembly is worn. The thing that I found worn the most was the actual thru holes in the frame that this rod goes thru. Has anyone else experienced this? I noticed that this causes a lot more play to the idler assembly compared to the one on my other 716H. This may be the source to my belt ware! Any comments???
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I made the original comment about tracking. Nearly every time I have had a major belt problem, it has been because of mis-alignment of the belt with respect to pulleys or idlers. In most of the instances where the belt has several bends in it, especially reverse bends, a factory belt will always last much longer than aftermarket. It has to do with the layup of the cords within the belt. If the belt is not built with the cord layup designed to meet the flex requirements, the belt will literally tear itself apart, even if properly aligned. I have never had the problems that you stated above with the wear on the pivot. If the wear is enough to set the idlers at an angle, or to make the pulleys and belt have a significant vibration when engaged, then this could be the problem.
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Are you using the deck that came on the tractor? Reason I ask is, I have noticed when using a 48" deck off a later series, like off a 900 series, the drive pully on those decks looks to me to be stamped, not cast. They have a sharper edge to them and I believe the alignment is a little different. I go through more belts with the 900 series deck I have not matter what tractor I am using than on any of the 700 series decks. Not sure this is the reason why, just an observation. Brent
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Hi, You have discovered the most common cause of belt rolling on these tractors. We have fixed a number of them for this problem. We get a new shaft and grind the welds off the spacer welded on the left side of the frame and make a new one. When welding the new one on, put the shaft in and position the spacer to the lower rear side of the hole, this is where it was originally before it wore forward and up. Weld it in and belt rollover problems will usually be fixed. Al Eden
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Al By belt roll over, I asume you mean the belt rolling over on a pulley, am I correct? This is not the problem that I'm experiencing, I just seem to wear OEM belts too often. As for your repair suggestion, that was my plan of approach as soon as I have acess to a welder. My only question is that you mention positioning the new shaft to the LOWER rear of the orginal hole. The thru holes on my tractor are what I call wallered out. The hole is very out of round. Most of the wear is to the bottom of the hole. My intentions were to position to the top of the hole when welding. Thanks for the input!!!
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HIi, As I remember and this may be wrong, I would need to look at a tractor, I thought the belt is pulling up on the pulley and the belt is also pulling forward on the pullies. This makes the shaft press upward and forward on the frame. This causes the holes to wear forward and up. By going to the bottom rear you shouuld get to the point the shaft was when it started its journey. Look at your shaft. Mark the place where the wear is the deepest. This is where the pressure was and the shaft needs to be moved in the opposite direction to get where it started. There should be almost no wear on the slack side. Al Eden
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Hi, I meant to address the roll over issue. When pulleys get out of line, the cord on the short side of the belt carries the most load. When it breaks, the next cord over is stressed. Once the second cord breaks, the belt wants to roll over. If the belt rolls once, it breaks the cords and it will never run straight again. The cord sequence can be a result of a roll over situation first. Anyway when the belt finally dies, the break looks like a straight across break, almost like a shock break. 7000 and 1700 / Sovs are prone to more belt failure when mowing at maximum height. Also the deck running with the deck lifted is death to belts. We had a 7117 getting severe use on a farm that was killing belts, the factory said to tell the guy to mow lower. He wouldn't. One of the service guys sent me all of the components of the center mower pulley with 2 of the top pullies. We turned down the sleeve that sets on the arbor shaft and put a pulley on 1 inch down and then the second pulley where it would normally be. Running on the lower pulley fixed the belt problem. Al Eden
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Al, Listening to that explanation makes a whole lot of sense!! I'll go back & look maybe I'm wrong. I'll check but considering how the belt contacts the roller I agree completely with your explanation. Your roll over explanation also makes sense. I see simular wear with conveyor belts here at work. We have some that are not easily accesable, so we can't check the tracking that often, if they get into the side on the bed it will act some what like this. Thanks for the help!!
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