PTO Driveshaft Shear Bolt

[Trails End]

The manual for the pto drive shaft (T40) for my Pronovost Puma-74 snowblower
calls for a M8 x 50mm safety shearbolt, but doesn't specify a grade. Does anyone
have information on what grade shearbolt this should be?

 

[gengine]

I think my auger says the same thing, but I've been using grade 3 sae bolts for the last few years

 

[Trails End]

My auger drive shaft shear bolt is specified to be a 1/4" NC x 1" Grade 2 with nylon lock nut.

 

[kco]

The Comer shaft for my Meteor specifies a metric grade 8.8 bolt. That is roughly equivalent to SAE grade 5.

The auger shear bolt is an SAE grade 2.

I suspect your PTO bolt is 8.8 but you should contact Pronovost.

 

[Trails End]

I already sent one email to Pronovost asking about an assembly/setup manual for the Puma-74
snowblower, but haven't received a response from them yet. My blower only had a operator/parts
manual but nothing on assembly/setup. I'll send another email, asking about the shear bolt.

 

[RickB]

The spec is for metric bolts 8.8 hardness.

 

[Trails End]

Thanks, all! I received a response from Pronovost, and they confirmed that the
M8 x 50mm shear bolt is grade 8.8!

Thanks again, and wishing everyone a very happy and safe new year.

 

[jimainiac]

Just curious, but I wonder how the metric hardness grading numbers compare to U.S., SAE grades. I always thought shear bolts were supposed to be soft so they'd break away before anything else broke.

 

[Trails End]

According to the chart shown at this web page Bolt Grade Markings and Strength Chart
metric class 8.8 is similar to SAE Grade 5.

 

[Trails End]

Ooops, Sorry Jim! I hit "Post Quick Reply" before I'd finished.
It looks like more snow coming before the end of the week. I just might
get a chance to try out the new snow blower yet. Should be interesting, with
the driveway covered with a thin layer of ice now after the inch of rain we
received here in Candia, and no chains on the tractor.

Happy New Year