One of my new projects will be to make a boom truck out of the old Toyota PU for getting firewood and other stuff
So I have a 12000 pound Horror Freight winch with 3/8" diameter cable (at least the is what the box says)
I am looking for a snatch block for the end of the boom like this one
(http://cloudfront.zoro.com/product/large/5RRT8_AS01.JPG?v=20141020161020)
My question is: should the sheave radius (the 'groove' in outside of the sheave)match the cable exactly or could a '1/2" radius sheave be OK for 3/8" diameter cable ?
It's worked fine for me.
Way back in time I took a class in winching; sponsored by Warn. I don't remember the percentage for certain but they told us the pulley groove should be larger than the diameter of the cable. Maybe by as much as 50%? Straining my memory on that. Also for better cable life the pulley should be large as possible. My winching pulley block has a wheel about 4 inches in diameter; rated to 20K lbs, IIRC.
Radius of the pulley channel- wider is fine
Diameter of the pully- larger is better, wire rope does not like small diameters.
If its designed for 1/2" and your running 3/8" it should be fine.
Only concern is the gap between the pully wheel and the side plates, insure its a close tolarance fit
I run one of these on my truck, its a nylon pulley wheel as I run a synthetic winch cable.
The sides pivot allowing easy cable access and then just use a D shackle, never liked hooks on my winch gear, but for your aplication it would probably be fine
http://www.amazon.com/BILLET4X4-SNATCH-BLOCK-9000-ARB/dp/B006YG8M4U
Thanks everyone
I thought it should match, but the 3/8 grooved sheaves were on the small side and not rated at a very high WLL
bigger is better it seems