Skidding logs with a 312-8

[Handy Don 13,146]

11 minutes ago, Ed Kennell said:

So, some where between 600 and 11,000 lbs.       I'm a Lab test guy so next time I have the 520H out I'll chain it to a 24" red oak and give it a jerk. The 520 with cab and dually is probably well over 1000 lbs.  I have a 3/8" chain I used to jerk out twelve 70 yo spruce stumps with my 5,000 lb F-150.     BTW, I use pieces of old fire hose on the chain to protect the trees and the tail gate.  When felling trees, I often use a 3/8" cable ****** blocked to the base of a tree so the pulling truck is in a safe location.

 

The 3/8" chain should break at 6600 lbs.

Adding anything to the connection like the straps that have “give” per @pullstart or tires cushioning the chain, lessens the deceleration and hence the force. This is good since it’ll reduce the risk of a chain failure, but not so good in that the applied force on the log will be less.

Even woven wire cable has some “give” as the strands compress together and the cable lengthens under load.

The “chain challenge” is that it has no give.

How many “fail” videos feature a tow vehicle ripping apart a stuck vehicle by yanking a tow chain after the steady pull didn’t work? It's because the high speed dynamic force is MUCH greater than the slowly applied force.

BTW, I’m not sure trying to break your chain under “lab conditions” is a great idea, Ed! 😉

And I think @Pullstart has some appropriately sized chain hanging on the front of one of his tractors, doesn’t he?

[SylvanLakeWH 26,834]

25 minutes ago, Handy Don said:

And I think @Pullstart has some appropriately sized chain hanging on the front of one of his tractors, doesn’t he?

And on the back... 

 

Here's the WHrat WHrecker before it moved to @Pullstart stables...

 

The chain was tested by suspending the entire Mackinac Bridge from it before I trusted it for the ... however, that was a static, not dynamic, test... so I will leave it to the experts @Handy Don  @ebinmaine  @Ed Kennell to calculate that variable... 

 

 

[Ed Kennell 39,947]

1 hour ago, Ed Kennell said:

I often use a 3/8" cable ****** blocked to the base of a tree

Sorry mods,  my sheltered me didn't realize this was a banned item.

[bassJAM 93]

5 hours ago, ebinmaine said:

Not to get too far into the minutia of this but I'm genuinely curious. Does anyone know how to figure out the actual load on the chain given a 600 lb tractor and a full total stop from say 6 mph?

 

You'd need to know the mass of the log to calculate the load on the chain.

 

 

3 hours ago, Horsin'round said:

F=m×a

 =600lb×-6mph

F=272.155kg×-2.68m/s=~-730N

 

It's a lot of force,  good reason to secure well with good equipment. 

 

You calculated the momentum which is mass X speed.  At a constant 6mph acceleration is 0, so Force is zero.

Edited February 4 by bassJAM

[Handy Don 13,146]

2 hours ago, SylvanLakeWH said:

 

“Looks ‘bout right"

“Hold my beer while I move this bridge..."

[Pullstart 63,862]

Without the scientific calculations, I know if you put a big lifted S10 blazer more under the mud bog than above it, and YANK hard enough to pull the back bumper off with a heavier truck, it’s going to eventually snap a 3/8” chain.  We’re talking about a log that I could physically move here.  I just don’t see where the actual argument is.  Either the tractor will move it, or it won’t.  If the chain breaks, I’ll supply the next one free of charge.

 

 

[AlexR 965]

On 2/5/2025 at 10:51 AM, Pullstart said:

Without the scientific calculations, I know if you put a big lifted S10 blazer more under the mud bog than above it, and YANK hard enough to pull the back bumper off with a heavier truck, it’s going to eventually snap a 3/8” chain.  We’re talking about a log that I could physically move here.  I just don’t see where the actual argument is.  Either the tractor will move it, or it won’t.  If the chain breaks, I’ll supply the next one free of charge.

 

I agree with you, I have abused 3/8" chain before, I have dragged 20" diameter 16' logs with 1/2 ton truck, yanked, pulled on things with mid size tractors. Haven't broken a chain.

Of course all those were older chains probably made with good steel so unless these new Chinesiam steel chain's are that weak. 

Also my understanding is that chains don't tend to whip around if they break, that is ropes and cables. 

 

I don't think we ever would see a broken 3/8" chain from a Wheelhorse pulling on anything. 

Edited February 7 by AlexR

[Pullstart 63,862]

9 hours ago, AlexR said:

 

Also my understanding is that chains don't tend to whip around if they break, that is ropes and cables. 

When they do break, they pretty much become rockets. 🚀 

[SylvanLakeWH 26,834]

[Wayne0 773]

1 hour ago, Pullstart said:

When they do break, they pretty much become rockets. 🚀 

Reminds me of the time my ex brother-in-law tried to yank out a stump with a chain and a cab over, double sleeper Pete.

3/8" chain broke and came through the windshield!

[RED-Z06 2,430]

The whip effect is from the accumulated stretch in a chain, its not alot of stretch, but when you have hundreds of links giving up just a fraction of a millimeter..and there is a sudden failure, the chain rebounds all at once.  Cable can do it too.

 

 

[Alrashid2 378]

Sorry for the delay guys. Caught that nasty flu and am still feeling like junk, but finally got out side to do some splitting!

I ended up not skidding any logs today and just bucked in place then split, but the Horse was able to easily transport my splits uphill across the property to season! Was a good day, I love this tractor!

 

 

Edited March 2 by Alrashid2
Photos

[8ntruck 7,287]

On 2/4/2025 at 4:40 PM, bassJAM said:

 

You'd need to know the mass of the log to calculate the load on the chain.

 

 

 

You calculated the momentum which is mass X speed.  At a constant 6mph acceleration is 0, so Force is zero.

what is missing is the amount of time that the tractor takes to go from 6mph to 0mph.  That will be a pretty small amount of time, which results in a large acceleration value, which then gets multiplied by the mass to make an even bigger number.

 

Another approach is to go to impulse equations.  i haven't messed with them in a long time.  Have to look them up and refresh my memory.