Pin Shear with snowblower fully raised

[KubotaAlex]

Hello, I have an issue on my SB10 blower I can’t seem to diagnose. Snowblower operates normally unless it is raised to above “7” on my 3-point control lever. Around 7 there is a loud rattle from potentially the gear box or auger. If the hitch is lifted any higher it will shear the PTO shaft shear pin.
with the tractor off (PTO disengaged) and the hitched raised all the way I can easily spin the blower and shaft by hand and no noise is heard. The shaft is the proper length and not bottoming out when fully raised. Any help would be appreciated!

I took the guard off the shaft and recorded a video of the issue linked below.
https://youtube.com/shorts/YCQELhkVekQ?si=Ntlj0mQY8bbS_Et5

 

[mcmxi]

Hello, I have an issue on my SB10 blower I can’t seem to diagnose. Snowblower operates normally unless it is raised to above “7” on my 3-point control lever. Around 7 there is a loud rattle from potentially the gear box or auger. If the hitch is lifted any higher it will shear the PTO shaft shear pin.
with the tractor off (PTO disengaged) and the hitched raised all the way I can easily spin the blower and shaft by hand and no noise is heard. The shaft is the proper length and not bottoming out when fully raised. Any help would be appreciated!

I took the guard off the shaft and recorded a video of the issue linked below.
https://youtube.com/shorts/YCQELhkVekQ?si=Ntlj0mQY8bbS_Et5

This reminds me of the guy who went to the doctor and said "Doctor, it hurts when I raise my arm above my head", to the which the doctor replies "Well, don't raise your arm above your head".

So, why are you raising the snow blower up so high with the PTO engaged? It's designed to blow snow off the ground, not off the roof of your car. I'd guess that the noise you're hearing is the U-joint straining due to the angle that it's being asked to run at. Turning by hand is slow enough to allow the U-joint more time to articulate, and so you're not hearing much. At speed though, the U-joint can't articulate fast enough due to the angle, which is generating a lot of resistance to rotation, and so you shear a pin.

 

[KubotaAlex]

Good points. That does make sense.
SB1064 Manual says not to exceed 25deg it seems like I am within that limit but still having that issue. Maybe I need to break the protractor out, lol.
Thank you for the insight!

 

[D2Cat]

Are you sure you're not bottoming out the PTO against the tractor because you have the gearbox lifted higher then the PTO shaft allows movement?

 

[mcmxi]

Good points. That does make sense.
SB1064 Manual says not to exceed 25deg it seems like I am within that limit but still having that issue. Maybe I need to break the protractor out, lol.
Thank you for the insight!

You're absolutely right that the manual states no more than a 25 degree up angle on the driveshaft while the PTO is engaged, but still, I don't see why you'd raise the blower up that high. I typically raise the blower no more than 6" to 8" off the ground when it's running, such as when I'm clearing a parking area with lots of forwards and backwards, but that's only 5 degrees or so.

As @D2Cat mentioned, you should check the driveshaft length as described in the operator's manual.

 

[KubotaAlex]

You're absolutely right that the manual states no more than a 25 degree up angle on the driveshaft while the PTO is engaged, but still, I don't see why you'd raise the blower up that high. I typically raise the blower no more than 6" to 8" off the ground when it's running, such as when I'm clearing a parking area with lots of forwards and backwards, but that's only 5 degrees or so.

As @D2Cat mentioned, you should check the driveshaft length as described in the operator's manual.

Shaft length seems perfectly fine. With the hitch all the way up there is still about 1.5 inches before bottoming out. I can almost remove the shaft from the tractor with it fully raised. I think the angle is the issue. And yes, I don’t need to raise it that high but it is much easier to not have to be concerned with pin shear when operating that lever. I ended up moving the lever stop to the other side of the lever so that helps. Thanks for the feed back!

 

[GreensvilleJay]

You might be able to add a 'limiter' to the cylinder. They're spring loaded,go around the shaft to limit how far a cylinder extends. A section of ABS and a gear clamp would work as well.
Hopefully you don't HAVE to use them until NEXT winter though !!!

 

[mcmxi]

Shaft length seems perfectly fine. With the hitch all the way up there is still about 1.5 inches before bottoming out. I can almost remove the shaft from the tractor with it fully raised. I think the angle is the issue. And yes, I don’t need to raise it that high but it is much easier to not have to be concerned with pin shear when operating that lever. I ended up moving the lever stop to the other side of the lever so that helps. Thanks for the feed back!

Good that you got it sorted out. We live in an imperfect world, and when a company says a product does A, B, and C it usually means under ideal conditions and/or only momentarily. It's like an add for the latest human stating that it can function without oxygen for three minutes. Technically correct, but not a real-world feature.

 

[Showmedata]

You might be able to add a 'limiter' to the cylinder. They're spring loaded,go around the shaft to limit how far a cylinder extends. A section of ABS and a gear clamp would work as well.
Hopefully you don't HAVE to use them until NEXT winter though !!!

I took the adjustable stop that's on the low side of the 3PH lever and moved it over to the high side. Then you can use to it to create an upper limit for the implement (and protect the PTO shaft).