Can you get any tougher than a grade 9 bolt?

G

ghostguy6

Joined
Aug 30, 2006
Messages
497
This is a bittle off topic but Ill give this a try here.
At the shop I work at we have a snow plow that mounts to our forklift. There is a 1/2 pin that locks the blade at 3 different angles. The design is rather poor as it puts all the blades force onto the the pin. the original pin sheared off in less than a week. None of the factory replacement pins lasted more than 2 weeks so we have slowly been working our way up with different items to try and find something tough enough to withstand the stress of the blade. Our latest attemp was a case hardened grade 9 zinc plated bolt. This bolt was able to withstand the shear strength but it still bent. Once it bends I have to cut it out to change the blade angle. Unfortunaltly the blade is subjected to shock loads to I cant just go with the hardest steel I can find, I need something tough rather than hard. What kind of steel would you guys recommend I try to make the pin out of? And what hardness should I have it hardened to?
 
The only thing I could suggest is to up the size of the bolt.I have seen grade 9 3/4" bolts put up with alot of stress,I'm not sure on the shock load but they are pretty strong.If you go too hard with the fastner you can damage your forks too.
 
I just talked to a friend who had a similar problem in a saw mill. I had helped him and heat treated pins....It comes down to poor design. The pins must be the weak point in the system otherwise you do more serious damage than breaking pins .But breaking pins that often is not good and the only way to solve it it to redesign the unit to take a bigger pin to distribute the forces over a larger area....Do the final resort !
 
You can try F911 or grade 12. I use grade 12 for steering on my jeep. It is stronger than grade 8 by quite a bit.
 
The people at www.boltstogo.com told me that their Socket Head Cap Screws, both standard and metric, are equivalent to a grade 12.

This should provide the tensile strength you need.

They also sell a spray on silicone that does a great job on snow plows, and is food grade.

The Socket Heads are not rated that high, but they are much stronger that the L9 or grade 9's.

Hope this helps.
 
ive run a dozer/ snow plow my whole life. Grade 8 bolts are plenty strong if they are made for the job . The kershaw plow blade bolts are all ive ever used. They are simply a tapered bolt so the run flush with the steel blade. Go to the KERSHAW site they with have them.
 
I have no experience with this so I'm wondering why I am about to make a fool of myself, but going back to the widening of the whole and pin the amount of stress the bigger pin can take is the square of the increase
 
If you are breaking the pin you are abusing the plow.
It is probably designed so the pin shearing is a safety fuze (it gives before major structural failure)
In upstate New York you never want to buy a used truck with a plow hitch because all of the "plow cowboys" will haul off and ram snowdrifts at 30-40 miles per hour rather than taking manageable loads at controlable speeds. When I worked in a body shop I saw a lot of frame damage from plow cowboys.

Your plow blade should not be subjected to shock forces if you are plowing safely


-Page
 
Sun shadow is so so true. The kershaw machine ihave run mostly the 46 and some 56 weigh around 30 to 40 thousand pounds imagine ramming a pile of gravel say 3 to 4 yards at 20 miles an hour. If a blade catches something hard like a block of steel and the bolts dont snap you can do serious damage to the machine. I broke off a plow once looked funny but wasnt so fun putting it back on . when you lift the back wheels 18 inches in the air you know youve come to a dead stop at 20 mph. lol
 
Ghost, check to make sure that the pin is a snug fit in the hole, and that there is no play between the parts. If there is any movement at all each "hit" into the snow will hammer on the pin. If you need to stay with the 1/2 inch bolt and all is tight check into a structural bolt. I do not recall how the grade is designated, but a bolt salesman will know, or a few minutes search on the internet will find it. Use washers if you use a bolt and nut, and torque it. A bolts strength is in it's clamping force and the friction between the parts carries the majority of the load.
Have fun. :) We don't have any snow yet!
~Alden
 
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