Grade 8 shear bolt confirmed!

   / Grade 8 shear bolt confirmed! #1  

SacandagaBrad

Gold Member
Joined
Mar 10, 2003
Messages
491
Location
Southern Adirondacks, NY
Tractor
TC24D
In an earlier post I described an instantaneous stall due to a shear bolt not breaking on a Woods SS52 snow blower blowing snow....

Well, I feeling better and got out to check the factory installed shear bolt on the drive shaft. It is a Gr 8 /forums/images/graemlins/mad.gif I picked up a handfull of Gr 2 and Gr 5 to try.

I encourage anyone with a new Woods snow blower to check the drive shaft shear bolt to make sure it is not a Gr 8. Easy enough to do without removing the bolt, you can see the head of the bolt clearly. If you've got 6 hash marks on the head, it's a Gr 8! Get it out of there. A TC24 at 2500 RPMs and little snow load could not shear it. That's asking for trouble IMO.

I just called my dealer to alert him to the problem, he was surprised and will check all new ones going out the door from now on. Seemed appreciative of the notice.

I would be interested to hear the results of your inspections. As pointed out by Rick in the earlier post, Woods indicated to him that the Gr8 spec in the manual was an error. Apparently they get their drive shafts from an outside source, who probably just used Woods spec without questioning it.

Anyway, if this saves anyone some serious damage to your tractror, it was worth the post.

Brad
 
   / Grade 8 shear bolt confirmed! #2  
You should remove the shear bolt and make sure that the pieces are lose or free to shear!
 
   / Grade 8 shear bolt confirmed! #3  
I just talked with a friend that has a Woods also and he was outside doing a repair. Seems that his also has the grade 8 bolt and as a result, he broke a weld in the impeller. Didn't know why until I told him of this post. Then he looked at the shear bolt and saw the reason. Wonder how long this problem has been going on for? Also wonder why Woods didn't do a safety recall notice with a new 15 cent bolt!!!!!
 
   / Grade 8 shear bolt confirmed!
  • Thread Starter
#4  
Junkman,

I'm wondering those same things myself. As I said before, my dealer was surprised and apparently had never checked or heard of the problem. He is both a NH and Woods authorized dealer.

I gave her a test run down a scraper bank using a Gr 2. Lots of chunk ice and some small stones from the road, no problems. That's my dad on the machine - he's much better at running tractors than digital cameras /forums/images/graemlins/wink.gif

Brad
 

Attachments

  • 352457-blowerweb1.jpg
    352457-blowerweb1.jpg
    19.5 KB · Views: 453
   / Grade 8 shear bolt confirmed! #5  
Lower Grade shear bolt confirmed!?
But, this also means that the quality of its gearbox of snowblower too is lower.

For ex., Grade 5 bolt is a medium carbon steel while Grade 8 is a medium carbon alloy steel. Shear capability of Grade 5 is lower than Grade 8. So, using lower grade shear bolt is like a fuse for a lower quality gearbox. Grade 2 is for lower quality cheaper gearboxes.

So, I guess Woods were probably told by their supplier that their gearbox was so good quality that they could resist a shearing force of even 4000-5000 pounds which is the shear capability of Grade 8. Isn't there any saying like "Tell me your shear bolt I will tell you its quality of your machine."
 
   / Grade 8 shear bolt confirmed! #6  
Wouldn't the diameter of the shear bolt also be considered in the design calculations.

Egon
 
   / Grade 8 shear bolt confirmed! #7  
Yes, it is a fuse for the gear box, PTO shaft and also the transmission. You use the softest bolt that will do the job, not the hardest bolt that it will take. Most but not all shear bolts are grade 2. All you are doing here is trying to stir up trouble.
 
   / Grade 8 shear bolt confirmed!
  • Thread Starter
#8  
</font><font color="blue" class="small">( So, I guess Woods were probably told by their supplier that their gearbox was so good quality that they could resist a shearing force of even 4000-5000 pounds which is the shear capability of Grade 8) )</font>

Not quite sure what you mean, but their gear box and erroneous Gr 8 shear bolt were high enough quality to stop a 24 hp diesel tractor cold in its tracks operating at full PTO speed, without damage to their implement. The shear bolt isn't only to protect their gearbox, it is also to protect whatever tractor it's connected. I would hate to think my weakest link was somewhere deep in the PTO transmission. That repair would probably cost more than the implement! I wonder what would have happened if I had a 40 hp tractor.

Brad
 
   / Grade 8 shear bolt confirmed! #9  
I have a 4 to 5 year old Woods snowblower on the back of my 40 HP New Holland. It has grade 4 shear bolts in the PTO and the sprocket assembly and they don't slow my engine down at all. When I hit a golf ball sized stone they immediately shear. That's why I always carry a zip lock bag of them in the toolbox.
 
   / Grade 8 shear bolt confirmed! #10  
How many hash marks are on a grade 4 bolt?????
 
 
 
Top