Kubota 54" Deck - Wearing Deck drive belt

[sdk131]

I will try to get a good picture later, but has anyone else had this issue?

Two year old 54" deck on a BX1870, and the deck drive belt appears to be rubbing on the mounts that the black plastic pulley guards are attached to. It has worn the top and bottom of the back side of the belt quite a bit. At the current rate of wear I suspect I may only get two more years out of the belt before it fails. Doesn't seem like I should have to be doing deck modifications just to avoid wearing the belt.

 

[Grandad4]

Something is not right with the belt installation, or something is bent or misaligned. It should not rub or make contact with anything but the pulleys. The belt should last more than two years with normal use. Don't wait until the belt is in tatters to replace it. The cut quality will degrade due to slippage with an old belt.

 

[sdk131]

Here are a few pics...if anyone sees anything obvious please let me know.

 

[wrooster]

i have a 6 year old BX1860 and the same 54" deck; i'm still on the original belt and it sure doesn't have indications of banging into the guard mounting brackets like yours does.

a couple of thoughts:

1)
if the pivot point of idler pulley arm (the idler pulley is the one with the spring attached to it) is "frozen" in place, it may not be tensioning the belt correctly (especially under heavy cutting load) -- the result may be that the belt is "flapping around" a bit since it is not properly tensioned. your pictures seem to show two different periods of time -- one picture (center above) has some telltale signs of recent greasing at the idler pulley arm, whereas the other (far right above) does not. if the idler pulley arm can not freely move, you will certainly have a tensioning issue as the belt stretches and wears. if you have not been greasing the idler pulley arm zerk AT LEAST annually with a good quality grease, i would disassemble the idler pulley arm from the deck, clean and inspect the bearing area thoroughly, reassemble, grease, and then check for smooth and free movement of the idler pulley arm before reattaching the tension spring.

2)
it is also possible that one of your spindles is loose or worn, leading to wobbling. it may be difficult to detect this when the drive belt is under tension. remove the belt, and check that each spindle is a) securely mounted to the deck itself, b) there is negligible axial and radial runout at the spindle bearing, and c) the spindle bearing rotates smoothly. if the spindle is rocking in the mount, or the bearing is wobbling, this will lead to displacement of the drive belt. note that it is not unheard of here on TBN to read about loose spindle mounting bolts; unfortunately, by the time you discover the bolts are loose, something else is usually damaged.

3)
ensure that there is travel left on the idler pulley arm; if the belt has stretched enough, the idler pulley may have reached it's maximum swing position, and can no longer hold the proper belt tension. correspondingly, ensure that the tensioning spring is in fact sufficiently drawing on the idler pulley arm.

wrooster

 

[sdk131]

Thanks Wrooster for the thoughts and the pics. I can actually see the same wear (although not quite as bad) on your belt in the third picture down. Perhaps I just have a lot more mowing time than you do? Each time I mow it is about two acres, and I live in MD so the mowing season may be longer by two months. All of the pics were taken seconds apart with no cleaning or anything else in between. The culprit really seams to be the second bracket in from the right on your 5th picture. Since I can see the same wear on your belt too, it must be somewhat normal. My gut is telling me that they just did not leave enough clearance in this location, as the other three brackets seem to have more clearance between them and the belt. This one is just oddly close. At this point, if everything else checks out I may just take a grinding wheel to it and remove 1'8" or so from the "hump" that is formed into the bracket. Those brackets are there solely to hold the plastic guards, so I can't imagine that removing a little material would compromise anything.

 

[kevinj]

They flop around a bit at low rpm.

When out mowing be over 2900 rpm and the belt will run smooth.

 

[David_Kb7uns]

I have a 30 series bx with the 6 bolt flange. Have some friends with 50 and 60 series with the 4 bolt on their BXs and have seen at least 2 where the bolts loosen up and either the pulley gets off center or start egg shaping the pulley holes and move around and then the belt starts jumping and oscillating and as it goes it will wear the v of the belt unevenly and then the jumping gets worse as time goes on.

Just to let you know, I did replace the belt on my 60 inch deck this summer and the tractor was new in 2005 (11 years and they were not easy ones) this is on the older deck with 6 bolt pulleys and the metal belt guards.

David

 

[4570Man]

Is your belt tensioned properly? My Kubota belts run with similar tolerances and they don't rub. I have over 1000 hours on some belts. Kubota got it figured out with the double belt. I never get anything close to their belt life on my other mowers. And my F2560 will deliver a lot more power to the blades than my other machines without the belt slipping.