When Shear Pins Don't - Broken Driveshaft Yoke

zkurtb · Jan 6, 2015

I hit a rock with my Allied Buhler 60" snowblower. Not the first time, and the shear bolt has always done it's job. But not this time, even though it is the same grade of bolt. Something had to give. I guess I'm lucky It wasn't worse. Pictures are of the yoke that connects the driveshaft to the blower, it's what was sacrificed. The u-joint is still intact. Anyone know where to get replacements? I'm starting to call dealers, but guessing they may be expensive, wondering if there is an alternate source for these. It is a single keyed shaft, not splined.

Opti-Mist · Jan 6, 2015

My first stop would be Tractor Supply. Should not be high dollar.

farmer2009 · Jan 6, 2015

TSC or Rural King. It isn't special unless it's metric but these two places should have those also.

flyerdan · Jan 6, 2015

The dark discolorations on the second picture indicates that there was a fracture there for some time before the failure, probably from another shear incident. That's probably why the yolk failed before the pin.
Even when you get a replacement, I'd probably grind out and braze that one back together just as a backup, unless they're dirt cheap and you pick up one for a spare.

DJ54 · Jan 6, 2015

Check your area for drive line repair shops, or, heavy duty truck parts places. Several HD truck parts businesses in our area, also do drive lines/pto shafts for large dump trucks, and other applications. They have about every size imaginable on hand.

hosspuller · Jan 6, 2015

I believe Flyerdan has a good handle on the cause of this failure

zkurtb · Jan 7, 2015

Thanks for all the replies and insights. I ended up ordering from a retailer/dealer. Around $50. I had tried looking at TSC website TSC Yokes although I hadn't called them, and much other web searching, found lots of yokes but not this one. We do have a good heavy duty truck repair/parts shop where I get snowplow parts, hadn't thought about trying them for this.

The main challenge for brazing would be the loop for the u-joint that has been deformed and stretched open as can be seen in the second pic. I'm not an experienced welder/brazer though I've done a bit. The part being cast, I understand it would have to be preheated and slowly cooled to prevent cracking. Wouldn't hurt to try.

Interesting thought about it already being cracked, the rust discoloration does seem to indicate that.

Stimw · Jan 7, 2015

You need to make sure that you have a no code bolt as in no marks on the top. A grade 5 or 8 would be too hard for shear.
If shearing is rare you might go a bolt size smaller so it will shear easier to stop this from happening again.

zkurtb · Jan 8, 2015

Stimw said:
You need to make sure that you have a no code bolt as in no marks on the top. A grade 5 or 8 would be too hard for shear.
If shearing is rare you might go a bolt size smaller so it will shear easier to stop this from happening again.

It is a grade 2, as per manual specs. Think I'm going to replace it with another since it didn't give...
It's sheared a number of times in the past, so don't know why not this time.