Snow Help PTO Drive Shaft

[Lt74]

Used my Kubota BX1870 this past storm, did four driveways twice. While finishing the last driveway, I heard a loud bang, snowblower stopped and I found the PTO driveshaft on th aground, universal joint shattered and the shaft a minor bend. I had not hit anything or even going into deep snow. I checked underneath could see no obvious problem, so I ordered new shaft for $380.00. Put it on with no problems used if for a few minutes and then another bang! I am having there Dealer pick it up and repair it but was wondering if anyone had this problem or an idea. As far I can see everything is aligned but obvious it is not.

Any help for a retired semi-idiot?

Thanks

 

[wrooster]

I checked underneath could see no obvious problem, so I ordered new shaft for $380.00. Put it on with no problems used if for a few minutes and then another bang!

1) Is the PTO shaft the correct length for the application? In other words, at both the top and bottom of TPH travel, the PTO shaft tubes are sufficiently engaged (overlap) but also not being placed in compression, correct?
2) Is the PTO blower equipped with, or was it originally equipped with, a clutch such that if the torque being applied to the augers is too great there is a mechanism for permitting slip?
3) Has a shear pin in the auger drive shaft assembly been replaced with a non-standard part -- such as a grade 7 bolt or similar?
4) Looking inside the auger housing, is there any sign of binding or such (bare, scored sheet metal), where the auger has made contact with the housing due to a bent auger blade?
5) You mentioned the u-joint failed -- which u-joint was it, towards the tractor end or towards the implement end? Did the same one fail both times?
6) Really stupid question here, but is the PTO shaft sized for the tractor PTO and snowblower? I have the same tractor and I don't know that the 15 or so HP available at the PTO could bust any standard PTO shaft but I just wanted to check what flavor shaft you are using. Is it one that came with the snowblower, one you obtained locally, or other?

wrooster

 

[AStanton]

Lt,
I find it kind of strange and timely that you post this issue with your PTO at this time. While using my rear blower during this past big snow storm, my PTO also shut down abruptly. I thought it was the shear pins; no, shear pins were fine. Then I examined the collar where the PTO attaches to the tractor and found the problem. The PTO shaft became unattached due to a missing bolt that held the collar together. Attached is a pic of the PTO shaft. Note the shinny new bolt to the right. That's the replacement bolt I reinstalled. Luckily I didn't suffer the catastrophe that you experienced. I wonder if you had a similar bolt on your PTO shaft and experienced the same loose bolt.

 

[freddyr]

Lt,
I find it kind of strange and timely that you post this issue with your PTO at this time. While using my rear blower during this past big snow storm, my PTO also shut down abruptly. I thought it was the shear pins; no, shear pins were fine. Then I examined the collar where the PTO attaches to the tractor and found the problem. The PTO shaft became unattached due to a missing bolt that held the collar together. Attached is a pic of the PTO shaft. Note the shinny new bolt to the right. That's the replacement bolt I reinstalled. Luckily I didn't suffer the catastrophe that you experienced. I wonder if you had a similar bolt on your PTO shaft and experienced the same loose bolt.

I think that shinny bolt u put in is a shear bolt and when installing has to be installed with a torque wrench.

 

[oosik]

AStanton - that shiny bolt IS a shear bolt. It is the only thing that holds the two back plates on the U-joint together. I have such a setup on one of my pto driveshafts and it only requires that the bolt be snugged down tight. However, it is important that the bolt used is what the manufacturer recommends for the shear bolt - probably grade 5. If you can not find the manufacturers recommendation I would suggest using a grade 2 bolt. The worse thing that can happen is you will snap a few more bolts than if it were supposed to be a higher grade.

LT - there is something seriously out of adjustment/alignment on your blower. Under such conditions as you explain - it would be normal/usual to have a shear bolt snap or the slip clutch slip. Having a U-joint explode/bent drive shaft is not a normal thing. I would be certain that the dealer not just repair the unit but determine the cause of the problem and address that.

 

[AStanton]

Thanks for the advice, gentlemen.

 

[brown40]

Just out of curiousity: How much of an angle is your driveline operating at?
How much overlap of the inner & outer PTO shafts is there?
Is your three point fixed firm, or does it swing side to side a bit (swinging angles & torque)?
If angle is good, and overlap is good, and its not too long (bottoming out against pto), then slip clutch/shear pin failed, and need to drop a grade of bolt or set the clutch lighter.
380.00--ouch! Nice guy on ebay makes nice heavy drivelines, usually get a slip clutch line at a better price than others offer for an unprotected line. Georgia is in the business name.
Good luck--its something simple.

 

[Lt74]

Thanks to you and every one who replied. This is the Kubota snowblower and the PTO came with it, the one I ordered was the same and came from their booklet. I cannot see an obvious problem with it. I have replaced one shear pin last year, worked like it should when I hit a chunk of ice. I did the four long driveways this year, I also replaced another shear bolt at the auger but then did four more driveways, (nice to be retired). I am waiting for the dealer to pick up the tractor and will follow all the advice on having them explain the cause and fix. Murphy's lawn but another storm is do Monday 8 -12.

Thanks again!!

 

[oldtimer 66]

The two matting surfaces at the shear bolt area need to be crisp and clean. If the bolt was loose and surfaces were slightly apart then maybe the shear bolt rolled over slightly and then sheared. If that happened then the next shear bolt will not last as long. See what the dealer says

 

[Kanook]

Lt74....any possibility that the u-joint is exceeding it's recommended maxinum angle when the blower is raised?...I think it is 15 degrees.

 

[PILOON]

Exactly, the surfaces act like a shear therefore edges need to be sharp.
Generally grade 5 is suggested as they shear with a clean cut while softer bolts bend and elongate B4 shearing and mess up the cutting edges.

 

[oldtimer 66]

PILOON we are correct but I missed the question. After I re-read the post he installed a brand new PTO shaft and it immediately broke after a short period of time, so there must be some thing else going on. One other note, my relative had a John Deere square bailer. One of the few around, everything else would be a New Holland. On the flywheel shear bolt setup JD installed / pressed in hardened bushings from the factory. The shear bolt ( body ) would shear between them. Longevity I assume plus the flywheel is rather expensive. The mating piece not so much. Later.

 

[SeymourBota]

All replies seem to focus on the assumption that it is a rear blower. Being a BX1870, I assume it is a front blower. OP, please confirm.

On the front blowers, if the gears and chain at the rear of the blower loosen, they could move around and cause the mid pto shaft to bind, causing the problem described.

 

[PeterK]

Dumb question but are your sure that the pto locked with a 'click' when you installed it? If not, it would fall off, bang as it hit something that bent it and maybe even smash the u-joint carrier.

 

[PILOON]

It is possible that the dealer simply supplied you with a generic new shaft that needed to be adjusted by trimming it to proper length.
When lowered it could run OK but raising an implement with too long a shaft could cause that second failure.

 

[Lt74]

Thanks to all who replied. This is a front snow blower, Kubota and set up by the dealer. I used it last year with no problems except for a shear pin (which I expect). So I just got it back from the dealer (2 weeks, but a lot of snow for our area). Their diagnosis was missing carriage boalgts and allen screws, also the bearing holders looses. They replaced the parts and tightened the holder. I have used it a couple of threes times since, including one 17" storm. NO problem and it ran like new. I cannot find the 'carriage bolts" on my manuals so I will go back to the dealer and have the service guy point th eprolbem out so I can keep an eye on it.

I lube all points and have not observed anything loose but according the service order the bolts were missing!

Thanks again and I hope this information helps some other BX 1870 owner avoid a problem. If I get any better information from the service people I will update this thread.

 

[aczlan]

Lt,
I find it kind of strange and timely that you post this issue with your PTO at this time. While using my rear blower during this past big snow storm, my PTO also shut down abruptly. I thought it was the shear pins; no, shear pins were fine. Then I examined the collar where the PTO attaches to the tractor and found the problem. The PTO shaft became unattached due to a missing bolt that held the collar together. Attached is a pic of the PTO shaft. Note the shinny new bolt to the right. That's the replacement bolt I reinstalled. Luckily I didn't suffer the catastrophe that you experienced. I wonder if you had a similar bolt on your PTO shaft and experienced the same loose bolt.

If you look on yours, is there a groove on the inside of the collar (where it sticks into the u joint) that you can put a circlip into keep the two halves together?
Our Kubota tiller has an almost identical setup for the shearpin but it has a circlip to hold the two halves together when the shear bolt breaks (no loose PTO shafts flopping around that way).

Aaron Z

 

[aczlan]

Thanks to all who replied. This is a front snow blower, Kubota and set up by the dealer. I used it last year with no problems except for a shear pin (which I expect). So I just got it back from the dealer (2 weeks, but a lot of snow for our area). Their diagnosis was missing carriage boalgts and allen screws, also the bearing holders looses. They replaced the parts and tightened the holder. I have used it a couple of threes times since, including one 17" storm. NO problem and it ran like new. I cannot find the 'carriage bolts" on my manuals so I will go back to the dealer and have the service guy point th eprolbem out so I can keep an eye on it.
I lube all points and have not observed anything loose but according the service order the bolts were missing!
Thanks again and I hope this information helps some other BX 1870 owner avoid a problem. If I get any better information from the service people I will update this thread.

The carriage bolts are probably the ones that hold the bearings into the mounting bracket (should be ~4 of them for that task)?

Aaron Z

 

[Lt74]

I will check. Thanks