Winch Shear Pins

[cranetruck]

Knowing the gear ratio and the number of layers on the drum, one should be able to calculate the pulling capacity with a shear pin of a given shear strength.....
Gerhard probably has the formulas handy (=I won't bother digging for them).

One or more snatch blocks is the best solution for most questionable pulls IMHO.

 

[gringeltaube]

Not that handy....
Had to do some measuring & testing first, with real size parts and “sacrificing” half a dozen of my pins to determine their actual strenght...



Found following:

1)Most of the (rebuilt) winches I checked have the hole in the input shaft already re-drilled to the next common size 5/16”!, same for the corresponding drive shaft yoke; probably during depot rebuilt?
2)The shear pins I used for this are home made, out of brass which already had proven to have a shear strength very similar to some old AL pins I once found hidden in a tool bag. (I’m positive these were OEM)
3)Two 7.1mm (nominal 9/32”) diam. pins sheared each at about 250ft-lb, inserted in its stock size 7.2mm diam. hole.
4)Surprisingly it took more or less the same torque (245ft-lb) to break the same diameter pin but in a hole enlarged to 8mm (5/16”+)! Tested for a second time to confirm this! Wish I had AL pins to compare in this case!
5)A 7.94mm (5/16”) diam. pin in a 8mm hole shears at 350ft-lb! I repeated this test too, to be totally sure. So certainly size makes a big difference here!

Having this data its simple math to at least estimate the real capacity of our 10K-Garwoods:
Not taking into account friction losses and the minimal force to overcome the internal band brake, we have a minimum of 250ft-lb multiplied by 23 (23:1 reduction ratio), makes for 5750ft-lb on the drum. The drum itself has a diameter of 5” so if we started with the wire rope all out, the center of the ½” rope would be winding in at a distance of approx. 3” from the drum’s axis, for the first layer. Since 3 inches = ¼ of a foot, and to maintain the same torque figure our force needs to be multiplied by 4 and that means that we actually could pull over 20,000 pounds, single line!!! (pretty tough job for a ½” rope… imagine with the larger pin or even a steel bolt!)

Now lets say we only pulled out the first 10 meters (last layer) for a light duty winching job only: then it would be pulling in at about 5” from the drum's center, so we have 5750 times 12, div. 5 = 13,800 lbs.!

Conclusions:
Are our winches under-rated? YES!
Do we need much stronger shear pins? NO! (IMHO)


G.

 

[Recovry4x4]

Gerhard, do you need some OE pins to do some testing on? If so PM me your address and I'll send you some for the cause!

 

[m16ty]

Gerhard, Thanks for your testing on this subject. Get some AL pins from Kenny (I'd send you some myself but I don't have any) and test them if you don't mind .

 

[tm america]

when i put my winch on it had a bolt i put the correct shear pin in there . it broke just winding the cable up on a tree with light load on the breaks.put another one in was testing the winch lock broke another one .that was the last time i used a shear pin .now i use a grade three bolt .havent broke the bolt broke the cable once but it had a bad spot in it i make sure to use snatch blocks if needed just dont like loading the cable like that if i can help it

 

[m16ty]

I've got a winch but haven't installed it yet so I don't have any first hand knowledge of deuce winches or shear pins. Seems like the more we talk about shear pins and answer questions the more questions it brings up.

Why are there reports of the pin breaking under no or very little load? Is there a bunch of bad pins floating around?

 

[swbradley1]

when i put my winch on it had a bolt i put the correct shear pin in there . it broke just winding the cable up on a tree with light load on the breaks.put another one in was testing the winch lock broke another one .that was the last time i used a shear pin .now i use a grade three bolt .havent broke the bolt broke the cable once but it had a bad spot in it i make sure to use snatch blocks if needed just dont like loading the cable like that if i can help it

If I were you I would be more worried about snapping bumpers off your truck than shearing a little pin.

 

[gringeltaube]

Gerhard, do you need some OE pins to do some testing on? If so PM me your address and I'll send you some for the cause!

Really appreciate your offer Kenny! If those are good ol' OEM pins I would hate to crack even one in pieces, just for testing purposes, even if it was "for the cause"... Let them live and die in real "battle"...
Can't we get known and proven "aftermarket" ones from one of our vendors? (Not for free of course!) I mean start with what can be readily supplied/replaced any time?
I would be glad to provide comparative data for anyone here and especially test those pins claimed to be the best!
Also thinking of including some steel in the next test series, for the sake of completeness...........! Guess I then need to build a heavy duty "pin cracker" with a hardened shaft...!

G.

 

[gringeltaube]

...........................

Why are there reports of the pin breaking under no or very little load? Is there a bunch of bad pins floating around?

Good Q.! .... But how "bad" must they be .....!?

Lets asume they give up at one half, no - one quarter! of the desired strenght (or what a "safe and sound" shear pin could do): that bad guy still would be able to produce way over 1ton of tension in the rope in its upper layer, more than enough to lift a complete MF engine W/tranny or at least .... have it tight and neatly wound on the drum!

G.

 

[tm america]

i was dragging fours deuces with my steel bolt and one snatch block.sw i think i had the aluminum shear bumper on there the way it got ripped off

 

[tm america]

ive always wanted to be able to run the aluminum pins i was thinking maybe drilling the shft for a second one near the end would give you enough pull without breaking things.i'd be very curious to see the difference in what it takes to shear two aluminum pins versus one soft metal or a grade 5 steel bolt.maybe you could do some testing of that.

 

[Recovry4x4]

Gerhard, I have enough for all my trucks for quite a while. I'd give up a half dozen without batting an eye. These are genuine GI pins and I've got $2 each in them. If I can't afford to cough up $12 for the cause, I'm in the wrong hobby. Gladly send them if you want them!

 

[avengeusa]

Gerhard, I have enough for all my trucks for quite a while. I'd give up a half dozen without batting an eye. These are genuine GI pins and I've got $2 each in them. If I can't afford to cough up $12 for the cause, I'm in the wrong hobby. Gladly send them if you want them!

I am planning a run of them, we have the proper material, and the specs, they will be the proper hardness ect, 1000 of them costs me a little over a grand....

lots of other items being made right now so i have to be "not spendy" on more projects, or sell a bunch of them off at 1.00 each to cover costs....

 

[gringeltaube]

....................... Gladly send them if you want them!

OK, you have convinced me! Lets see what they can "pull"!

PM sent!

TIA

 

[gringeltaube]

...... we have the proper material, and the specs, they will be the proper hardness ect,...........

So would you send me a pair to run them against Kenny's?
Then we can go: ".... and the winner is: ......"

G.

 

[SGTStewart]

opcorn:
This is gettin good!

 

[cranetruck]

While you are at it, could you test off-the-shelf aluminum and brass bolts too?

 

[gringeltaube]

Yes for the brass bolts (5/16" diam.)! Not sure if I can find them in AL here.

G.

 

[blacktop]

So I orderd 10 pins from memphis Equipment, they told me yep this is the correct pin for the m35. I recived 10 STEEL pins with flat heads the invoice said -
PIN SHEAR (M37,M715,,GMC,CCKW) . So I called them and told them I need the correct aluminum pin, the guy I spoke to wrote we off as a moron. I asked if they would send call tags to return them as they were wrong and he did. I recived my refund to day, the price I paid was $17.40 for 10 pins and $12.26 for shipping(OUCH) my refund I recived was 3 bucks. Dont get pins from Memphis.

 

[abh3]

Here's what happens when you use a bolt: http://www.steelsoldiers.com/deuce/26126-winch-fragged.html

My A3 has the hydraulic setup but the pressure valve seems to be set pretty low so the winch doesn't have that much pull to it, at least in terms of trying to pull out stuck farm tractors, even using the G.I. block...

The solution for those of us trying to pull big things out of where the shouldn't have gone, as opposed to pulling ourselves out, is having several blocks on hand for the job, NOT back at the shop, hanging in the barn where they are safe!!! Blocks are where you find them, just missed a few by running errands instead of stopping RIGHT THEN at the roadside junk-sale, they were gone an hour later. Keep your eyes open!