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  • redrive belt- fail

    hey guys i was out fly around and after about 45 mins that day , i look down and noted the rev gauge was peaking out to 7000 rpms and thought ok . time to land. but lucky i was around the air feild.now what had happen was the belt was slipping on the lower drive pully. i have a belt driven redrive- i thought to my self . 80 hours and the lower pully had worn away?? so i went to the back of the car and got out a brand new lower drive pully and replaced it and went up the runway got the rotors going and still the same thing happen the belt slipped. i had the devils horns growing out side me head, underneath the helmet, but then it accured to me that the belt i was using was a kevlar belt.kevlar belt has more reinforced strands to make the belt stronger, but less plyable ?the question is does anyone know much about them?i get the feeling if i turn the belt around it will be fine?but for the cost of a new belt its not worth it.. would a medium belt softer rubber be the go?does anyone know?cheers adrian

  • #2
    My first gyro had a belt drive and although it only had an EA 81 driving it, the time between new belts wasnt very long. My advice is to put a new belt on and read up on the amount of free play, I think that the belts stretch once warm and hence the problem as we usually check them when cold. Make sure the bolts on the lower pulley are torqued up right.I know they are not cheap but an Autoflight gearbox is the way to go and do away with belts full stop. Belt drives are a bit like drum brakes on a vehicle, not a lot of use although they did just fine till we got discs.

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    • #3
      Alloy pulleys tend to "grow" in size when they warm up and make the belt tighter.Yes Brian, Autoflight is the go.Aussie Paul.

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      • #4
        Hi AdrianI will give this my best shot. First off you say in your topic belt fail, but in your analysis you say the belt slipped.I am assuming after reading your post the belt actually slipped, belt slippage as Brian and Paul have said is normally attributed to incorrect belt tension. You also state that you say that if you turn the belt around it should be just fine, I am a little confused as to what exactly you are saying here.Rubber and and kevalar impregnated rubber belts are also very dependant on pulley diameters, if the pulley diameters are actually to small it will actually accelerate the wear of the belt and in some cases lead to premature belt failure (snapping)Pulley wear also has an effect on belt life and can also accelerate belt wear. Incorrect pulley alignment will cause the belt to ride to one side of the pulley and cause the belt to rapidly wear on one side also, maybe this is what you are reffering to when you suggets it should be fine if you where to turn the belt around.I had a belt redive on my gyro and the previous owner before me also, that machine provided us both with many hours of trouble free operation. Sure gear redrives are nice but as the guys said they are a little expensive and can also add unwanted weight. Hope I have helped in sone way, if there is anything else you would like to know just ask.CheersDarren

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        • #5
          thanks guys i do realize that autoflight would be the way to go , what i have found using the kevlar belt that , as they are a stronger belt able to retain there teeth on the belt, but what i found is that it seems to have lost the edge so it may require alot more tension to operate on such level as a new belt . but using such belt would lower the life spand of the lower pulley, being a courser belt.even thought the belt looks fine having more tension on the belt . or turning the belt around, may swear out the lower pulley fasteror use a medium more plyable

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          • #6
            the belt seems to have alot tougher teeth and over time with the usage of the throttle the belt appears to have warn- taken off a small portion of the driving side of the tooth . or though it looks fine, i know, the last belt i had - it was the original belt i got with the gyro and i tensioned it up , after 5 hours of flight it lost all the teeth in about 3 seconds, landed in someones back yard. luckily i knew who it was.im using twin belts to try save the lower pulley longerbut im thinking the kevlar is too good what what the purpose is for either that or it requires more tensioning over time.cheers adrian

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            • #7
              Gday Yoshi (Darren) I suspect that Adrians belt has the square profile teeth and that the leading edge has worn on those teeth causing them to round out. I suspect his reasoning is if

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              • #8
                the belt im using is a round tooth belt . or though it dont make sense to turn it around. that was sort of the question. would it make a difference to turn the belt around?cheers adrian

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                • #9
                  Notched or multivee belt??Aussie Paul.

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                  • #10
                    i dunno what the difference is . i use a 880 ml by 8ml

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                    • #11
                      Sorry Guys I am not commenting on the belt drive but just noticed that Yoshi had an input and I would like to get in touch with him Or if Yoshi gets back online please give me a mail deejaypee57@yahoo.comName dave pickard

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