Snowblower Snowblower sheer bolts.

[RickB]

Thank you for the metric lessons. I was not aware of the differences in hardness ratings. Also, not to sound too ignorant but...you mention that the bold should be long enough that the bolt shear through the shaft as opposed to the threads, however, the bolts that came with the blower are threaded all the way up to the head. Can you think of a reason why a manufacturer (especially one from Canada where metric reigns supreme) would use metric for one bolt and SAE for another? And another question (sorry about the whole "teach me metrics" thing), I am under the impression that the M6 is refering to the pitch of the threads?

The PTO shafting is sourced by the blower manufacturer from a third party that specializes in drivelines. Few, if any implement manufacturers make their own PTO shaft assemblies, including Deere, CNH or AGCO, let alone short line manufacturers. The best value in PTO shaft assemblies currently is of a metric design, hence metric standards and dimensions on all things related to your PTO shaft except perhaps the attaching yoke bore diameters which are dependent on matching the tractor and implement. M6 (or M10) refers to the bolt diameter. Thread pitch is expressed as a decimal eg M10-1.25x40MM would be a 10mm diameter bolt with a 1.25 thread pitch 40MM long. 40MM bolts can be obtained either fully threaded or partially threaded. Of all the criteria you need to look for, settling for a full thread bolt is an acceptable choice. I would prefer shearing through a full shank just to get that little 'extra'. I'm a little surprised the original was full thread, but certainly won't dispute the fact.

I apologise for constantly referring to your PTO shearbolt as a 10MM. I re-read you post and see it is 6MM. The rest of my posting is accurate, and I would be even more diligent about finding M6x40 bolts with a full diameter shank at the shear point. 6MM seems small for the PTO shearbolt. My Puma 74 has an M10 bolt in its PTO.

 

[WilliamBos]

Our Buhler Farm-King calls for Grade 8 shear bolts.

 

[atgreene]

Get a slip-on clutch for your pto shaft and adjust accordingly so it will slip before the pins shear. Make sure you shorten the shaft as necessary to avoid binding the drive shaft by making it too short.

I did it to my blower to avoid replacing shear bolts.

Here's a link: http://www.tractorsupply.com/webapp...10551_10001_28194_-1______?rFlag=true&cFlag=1

 

[Woodland]

That is a very interesting option. I may look into that.

 

[atgreene]

Just make sure you properly adjust the clutch to slip when needed.

 

[SPYDERLK]

Thank you for the metric lessons. I was not aware of the differences in hardness ratings. Also, not to sound too ignorant but...you mention that the bold should be long enough that the bolt shear through the shaft as opposed to the threads, [[[however, the bolts that came with the blower are threaded all the way up to the head.]]] Can you think of a reason why a manufacturer (especially one from Canada where metric reigns supreme) would use metric for one bolt and SAE for another? And another question (sorry about the whole "teach me metrics" thing), I am under the impression that the M6 is refering to the pitch of the threads?

Apparently th operation does not call for the extra shear strength of a full shank bolt. The threads give the function of a notch at each shear point as you will often see done on full shank bolts modified for use as shear. Full thread provides a cheap alternative.
larry

 

[Bedlam]

Just wanted to throw this link as well what a difference in price from the TSC clutch. They look the same but maybe there is a difference.
SLIP CLUTCH W/1-3/8X6 MALE X 1-3/8X6 - Agri Supply

or

Tractor Supply Company - PTO Slip Clutch, 1 3/8 in x 1 3/8 in

 

[GreenMtns]

The PTO shafting is sourced by the blower manufacturer from a third party that specializes in drivelines. Few, if any implement manufacturers make their own PTO shaft assemblies, including Deere, CNH or AGCO, let alone short line manufacturers. The best value in PTO shaft assemblies currently is of a metric design, hence metric standards and dimensions on all things related to your PTO shaft except perhaps the attaching yoke bore diameters which are dependent on matching the tractor and implement. M6 (or M10) refers to the bolt diameter. Thread pitch is expressed as a decimal eg M10-1.25x40MM would be a 10mm diameter bolt with a 1.25 thread pitch 40MM long. 40MM bolts can be obtained either fully threaded or partially threaded. Of all the criteria you need to look for, settling for a full thread bolt is an acceptable choice. I would prefer shearing through a full shank just to get that little 'extra'. I'm a little surprised the original was full thread, but certainly won't dispute the fact.

I apologise for constantly referring to your PTO shearbolt as a 10MM. I re-read you post and see it is 6MM. The rest of my posting is accurate, and I would be even more diligent about finding M6x40 bolts with a full diameter shank at the shear point. 6MM seems small for the PTO shearbolt. My Puma 74 has an M10 bolt in its PTO.

Well since I just had my first auger shearbolt go and had to replace it AND I came across this thread that got me looking at my Puma 64.

RickB, I have gone through the parts list for this blower and there is not a single Metric bolt in the blower. Odd, since it's made in Canada.

The manual states on page 10 section 11--Always use Grade 5 shear bolts. BUT

On page 15 of the parts list it reads Ref: 25 Part# Std. Shear Bolt 1/4" NC x1" lg grade 2 + nylon locknut.

They also don't list any other bolts as a shearbolt but do show a Ref 8 Part # 300-32370 Bolt 1/4 NC x2 1/2 lg + nylon locknut at the PTO shaft end on the blower. I assume (and we all know what assuming does ) that this is the PTO shearbolt.

They kind of contradict themselves in a few places but I am going to use a grade 5 at all points since the instructions clearly state that grade for all shearbolts.

 

[RickB]

Well since I just had my first auger shearbolt go and had to replace it AND I came across this thread that got me looking at my Puma 64.

RickB, I have gone through the parts list for this blower and there is not a single Metric bolt in the blower. Odd, since it's made in Canada.

The manual states on page 10 section 11--Always use Grade 5 shear bolts. BUT

On page 15 of the parts list it reads Ref: 25 Part# Std. Shear Bolt 1/4" NC x1" lg grade 2 + nylon locknut.

They also don't list any other bolts as a shearbolt but do show a Ref 8 Part # 300-32370 Bolt 1/4 NC x2 1/2 lg + nylon locknut at the PTO shaft end on the blower. I assume (and we all know what assuming does ) that this is the PTO shearbolt.

They kind of contradict themselves in a few places but I am going to use a grade 5 at all points since the instructions clearly state that grade for all shearbolts.

My response was directed to the owner of a Pronovost Lynx which has a metric shearbolt in the PTO. He was being given bad advise by someone who does not understand metric hardware, specifically that the 6mm PTO shearbolt was of grade 2 hardness. The point of my post was to inform the OP on how to describe and source metric hardware; not to make blanket claims about everybody's snowblower shearbolts.

I'm baffled as to why you are comparing your snowblower to mine even though they are different sizes and models and based on the information we have both given, apparently have different series driveshafts with different sized shearbolts. The best advise I can give you is to follow the info published in your operator's manual.

 

[GreenMtns]

My response was directed to the owner of a Pronovost Lynx which has a metric shearbolt in the PTO. He was being given bad advise by someone who does not understand metric hardware, specifically that the 6mm PTO shearbolt was of grade 2 hardness. The point of my post was to inform the OP on how to describe and source metric hardware; not to make blanket claims about everybody's snowblower shearbolts.

I'm baffled as to why you are comparing your snowblower to mine even though they are different sizes and models and based on the information we have both given, apparently have different series driveshafts with different sized shearbolts. The best advise I can give you is to follow the info published in your operator's manual.

I fully understood your post and was not calling you down on it. I am just a little confused by my manual which is telling me one thing on one page and a completely different thing on another. It might be because my blower is 6 years old and maybe a design from "the past".