There are a lot of companys building different kinds of tools to deal with moveing logs, but one of the best designed log arches i've seen is from Norwood.
http://www.norwoodindustries.com/skidmate.htm
Look at their product line, as they have good products at a fair price.
One poster said he uses his loader to pull logs out backwards, but loaders aren't designed for those kinds of stress', and personally i'd NOT use that method! All of these smaller tractors (under 100 hp) these days don't have a frame, and they aren't all that hard to break in half!! It actually happens quite often.
I have a saw mill, so i do quite a bit of "skidding" logs out of my wood lot. I pick up one end with my 3 point, and go slow untill i get a feel for what's happening, and untill i clear any stumps, bumps ect. that could cause a problem. The heavier your tractor is the better for draft work, and an ag. tractor is the better choise for this job. I've pulled out some fairly big logs with my tractor, and some were much too big to pick up with my loader!! If you use common sense, bigger logs can be handled with a farm tractor, but it's really not the right tool for this job.
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If i have to move the logs a long distance i haul them with a farm wagon 10 ton running gear. This works very good!!
http://www.fototime.com/{6B0AADCD-3720-45BE-A3FC-1A319FDB6EA1}/picture.JPG
Once i get the logs on site, i saw them with my band mill.
http://www.fototime.com/{23954D38-E328-4C15-981F-49091FDAA81A}/picture.JPG
I mostly saw for my own use, so i saw a lot of construction lumber. Right now i'm getting ready to saw sone 3x6's for a loft in my shop.
http://www.fototime.com/{6AF8082E-1F0D-4073-BC88-237B65D6515C}/picture.JPG
It's really handy to have a mill on site to saw what ever you need when it's needed!!
I do have some nice hard wood sawn and drying on stickers. I try to keep some different kinds of lumber drying for later use.
http://www.fototime.com/{9A34DEB7-F187-40C1-A524-134E5D4A73D7}/picture.JPG
Hope you liked the pictures,
Robert