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Winch Shear Pins

Jakelc15

Jakelc15

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gringeltaube said:
For do-it-yourselfers or the ones who can't buy them so cheap or aren't so close by....
I just did some comparative testing with my own creation of a "shear-pin cracker" (pat.pend. :smile:) which actually worked better than expected.......

The OEM pins (including the broken core of my very 1st winch miss-hap...) snapped at about 160 ft-lb. More or less the same torque was needed for a home made one made of brass which I had used for years of "normal winching action" but later replaced when I found it with already some deformation.

Also I have a few larger ones of unknown application...(the M35 uses 0.279" x 2.125" measured inside cotter pin holes, these are 0.329" x 2.25") so I turned one down and it also took 160+ to shear it.

For comparison another "homemade" pin of unknown alloy but at least showing some temper... only resisted 100 foot-pound!

Next step will be trying to find 2024 or 2017 alloy locally and compare different levels of temper.
At least I know now what the goal is....:wink:

G.
Click to expand...

By looking at your data above and I could be wrong but 160 lb/ft should yield about 45,000 psi shear strength. So you should be looking for 2024 in a t4 or t351 temper which has about 42,00 psi shear. The 6061 t6 only has about 30,000 psi and I recall reading that someone tried this for a shear pin and they thought it broke very easily. I am assuming that is a 3/4" bolt you are using since you have a 1 1/8" socket! I am also interested in making my own pins. My winch currently needs one and I have none. Would 5/16" round be what fits the M35 winch shear pin hole?
 
m16ty

m16ty

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I wonder if you can get 9/32 rod. Kind of a odd size. If not you could turn down some bigger rod but it would be alot easier if you could find the correct size and people could make them that didn't own a lathe. If I think about it I'll talk to my supplier and find out.
 
Jakelc15

Jakelc15

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Ideally you want the pin as tight as possible. So there isn't any "slapping" that could cause premature shear. But it would probably work just as well if you are gentle with it.
 
Jakelc15

Jakelc15

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No that's not what I meant. I will not use a bolt but was going to try to use 5/16" 2024 T3 Aluminum round rod instead of the hard to find , no one will call me back about, oem size!
 
Evilone

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Sorry if this is a bit off off topic, but all this talk of shear pin material, temper and shear strength along with bits of block and tackle use is quite interesting and informative. Recovery is also part of my job and thought it relevant to mention that there is a great manual http://tinyurl.com/dj47fq in the TM's section, and just wanted to bring it to the attention of those that may be performing their recoveries safely and correctly or those who may have little knowledge but the means to injure or kill themselves or someone else let alone damage a very important piece of equipment. It is not a good thing to see a wrecker towing another wrecker due to stupidity or ignorance. It also may be a refresher for some and that is a good thing. I've benefited from going through some of the not so run of the mill 4:1 pulls and pick up on something forgotten from lack of enough practical use. I still enjoy rigging - it's good fun, but why does it have to be so frickin heavy!
 
avengeusa

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I can turn a few down, i have a lathe, and a mill

give me drawings

.280 dia, and exactly how long, and what size holes do they need to have, I have brass, and a couple different grades of aluminum......
 
Jakelc15

Jakelc15

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What I was trying to do was find the right rod stock so that anyone here could buy it and hack saw off the appropriate length and drill a couple of cotter holes in it. I think the 2024 Aluminum in a T3,T4,or T361 would be almost exactly what the Gi issue ones are. And the Gi ones are about 9/32" diameter. Which is hard to find in the proper alloy and temper. But if the 5/16 rod will fit it may open a whole new door to easier availability. And if your looking for the 9/32" 2024, goodluck, Alcoa doesn't cold form 2024 in that size. But then again those of us with access to a lathe can make all the shear pins we want out of 5/16" stock!
 
Jakelc15

Jakelc15

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I kind of dropped off looking for this, other things going on. I contacted a bunch of distributors and the ones that did contact me back didn't have what I was looking for. I'm going to try a local place again for 5/16" 2024 and see what kind of strength that yields.
 
smoothnu

smoothnu

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AL 2024 T3 or T4 has a tensile of 68000 psi a yield of 47000 and most important (to us anyways) shear strength of 41000 psi. I have no idea if this is to much for these winches or not. So I am probably going to go with AL6061 T6 which has a shear strength of 30,000 psi. You can buy a 5/16" 3' section for $2.26 at Reid supply company P/N mes-434 . This beats the heck out of the $3.50 per shear pin price.( I don't mind cutting my own.) Now, this info was relayed to me by a co worker. It being the weekend I have not been able to verify this myself. I hope this accurate and helps all of us that are in the shear pin dilemma. I will soon see. By the way actual size may be 9/32" but would it hurt anything and not be easier to drill out the pto shaft to 5/16" than it would be to turn down 5/16" stock to 9/32"? Seems like 5/16" material is a little easier to find. Just a thought
 
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