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Posted by David Sherman [72.47.9.228] on Saturday, February 19, 2011 at 01:51:10 :
In Reply to: Re: Favorite Stump Chain Size? posted by M Fanoni [32.174.30.147] on Saturday, February 19, 2011 at 01:05:33 :
If the man wants to buy a 1/2" chain, I'm not going to try to talk him out of it. It will certainly be stronger than a 3/8" chain. However, unless the back end of the truck is chained to a bigger stump, or he gets a running start and gives it an almighty jerk, he's not going to get 7000 lbs of pull on that winch cable. I think a PW weighs something around 5000 lbs empty. Say he puts 2000 lbs of ballast in the back. Say also he's parked on dry pavement (unlikely when pulling stumps) with a coefficient of friction of 0.7, which is probably on the optimistic side under real-world conditions. That means the maximum pull he can get is less than 5000 lb before the tires slip.
7100 lb is the safe WORKING load of grade 80 chain. It will take considerably more than that to actually break it -- something like 44,000 lbs using 200,000 psi steel (mild steel typically has a yield strength of around 100,000 psi, so 200K is conservative) -- so I think there's plenty of safety margin with the 3/8 and I would feel good about using it.
I agree with the other fellow who said to use the pintle hook rather than the winch. That's why I always do when skidding logs, though part of the reason there is that I prefer to drive forward. Still, there's no point in beating up the winch when you don't need to. The next question is how much stress can the rear frame crossmember take before it bends. I'm sure it'll take all that the traction of the truck can provide (about 5000 lbs) but if he gets a running start and gives it a jerk, at some point it will bend, and I'm pretty sure that point will be before a 3/8 grade 80 chain breaks.
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