Chain Strength

[DocHeb]

I had a great time during my first "real" tractor experience - using my new 5/16" chains to pull a "widowmaker" deadfall to the ground. It was nice to see the tractor pulling so hard that all four wheels were starting to slip - but it was not nice to see the new chain break at the link that the grab hook connected to. I had thought that the chain would have been strong enough, but obviously not. How can you tell the grade of a chain? I guess I need 3/8" chain, so is grade 40, 70 or 80 needed to withstand the pull of my TC40D?

 

[beenthere]

Could you post a picture of the broken chain and the link? Did it break before the dead tree fell? Was it a factory link, or home-made connection?

 

[DocHeb]

Can't post a picture for 10 more days as the chains are at the farm. These were premade chain sets made with 5/16" chain and grab hooks at the ends. They have a "goldish" finish, similiar to anodized nails I used to see at the hardware store.

Three wheels on the tractor were slipping, and as soon as I stepped on the differential lock, the chain broke without the tree falling.

 

[MikePA]

According to the <A target="_blank" HREF=http://www.awdirect.com/awdirect/catalog.cfm?dest=dir&linkid=109&linkon=subsection>AWDirect site</A> a 5/16" chain has the following capacities.

Grade 40 - 3,900 lbs $1.70/ft
Grade 70 - 4,700 lbs $2.15/ft
Grade 80- 5,100 lbs $5.25/ft

 

[ScottAR]

I use 3/8" welded link chain. I forget the number rating but it's rated for binding loads on 18wheelers. It'll take all my 1050 has, holds back the bronco as well.

 

[DocHeb]

I know that it depends on tires and ground traction, but how much pull do you think I could generate with my tractor before stalling. The chain I was using looks like the 5/16" Grade 70 chain. Boy, I thought that would be adequate.

 

[MikePA]

<font color=blue>but how much pull do you think I could generate with my tractor before stalling.</font color=blue>
Good question. I don't know.

 

[BigDave]

Doc,

I purchased 3/8" grade 70 chains from TSC. They are 14' lengths and come with hooks. I'm not positive, but the grade 70 was gold and grade 40 was gray at TSC.

I was dragging a section of trunk from a 3' poplar tree without too much difficulty until the trunk hit pavement...it would go no further. My TC33 gave it everything it got, but my weakest link was the tires. They didn't slip, they held fast to the pavement. The trunk wasn't directly behind the tractor, so I was pulling at about 20-25 degree angle, and the rear tires flexed about 5-6". I was afraid That I would pull one off the rim, spill anti-freeze all-over, and flip the the tractor. Anyway, I used the loader and rolled the trunk back onto the grass, where it still lies today. When, I'm felling like I need to work out some frustrations, I plan to fire up the big chainsaw and shoe that trunk who's the boss. Too bad I don't have a hockey mask. /w3tcompact/icons/laugh.gif

 

[WVBill]

Chris:

About a year ago there was a long thread here on TBN about using chains. The thread included a debate about what would happen if a chain under tension broke - would it snap and whip like a rubber band or cable or fall harmlessly to the ground... At the time, everyone had theories but I don't recall that anyone had personal experience as you have just had.

When your chain broke, what happened? Did it whiplash one end, send shrapnell flying or just fall harmlessly to the ground?

 

[DocHeb]

I must admit that I broke both of my chains (never let it be said that I'm not persistant, but you can say that I don't learn well from my mistakes). Both times the chain fell straight to the ground, and both times the link that failed (the one that the grab hook was hooked up to) dropped about five feet away. There was no recoil of the chain at all. I wouldn't expect any, since recoil would be caused by stretching (thereby storing energy). The chains don't stretch much. However, straps and cables do. That is why they will recoil when they fail under load. Also, straps, cables, and chains should not be used in combination, since recoiling straps/cables could carry the chains with them with tension failures.

By the way, the deadfall did come down as the second chain snapped.