[dsn_klr650] engineer question, (non klr, kind of)

[Ron Haraseth]

Good points on leverage multiplication. I would suggest you NOT use your local ACE as a source for the pulleys or cord. Hit up an REI or other mountaineering store that stocks quality components and request "STATIC" cord. Most cord has a lot of stretch ("dynamic") which you don t want in this situation. Ron ------------------------ Mark, I'm not an engineer but I'm not gonna let that stop me from making a comment. : ) I don't think it's the diameter of the pulleys that gives you an advantage but the number of wraps??? of cable between two pulleys. That is what gives you the mechanical advantage. If you are pulling 500 pounds with only a single cable connected between the 500 pounds and the pulling force it takes 500 pounds. If you put a pulley on the 500 pound end and attach the cable to a fix object near the pulling force, put the cable around the pulley and then connect it to the pulling force I think that would give you a mechanical advantage of 2 to 1 so the force required would be 250 pounds to move 500. Now if you added a second pulley near the pulling force you could wrap the cable around both pulleys and back to the 500 pound item and get even more mechanical advantage. Maybe you could figure it out by thinking about it in feet moved. Pull the cable one foot and you move the item one foot. Add a pulley and you could pull the cable 2 feet and move the item one foot. Add a second pulley and attach the cable end to the item and you could pull the cable 3 feet and move the item one foot. Secure the cable end at the pulley near the pulling force and you could pull the cable 4 feet and move the item one foot. I think I've got that correct. If not that is the general idea. The factor that really complicates your question is stuck in the mud. How deep, what kind of mud etc. I got my front wheel stuck a few years ago that I couldn't pull the wheel up at all. I had to lay the bike on it's side on a board I found and lever the wheel up and slide the bike out of the mud. I was alone and it took about all I had in me to get free. Took 45 minutes and I sure wish I had a camera with me that day. : ) One more complication is stretch in the 550 cord. I've pulled a 2 1/2 ton truck with 550 cord when I was in the military. It took a lot of wraps to allow that to happen but it was better than a bunch of guys pushing it. And just to keep making a pretty simple operation more complicated... : ) the pulleys have to be stronger enough to carry the load and you have to have a way to fix the pulley(s). Best, Jeff Saline ABC # 4412 South Dakota Airmarshal Airheads Beemer Club www.airheads.org The Beautiful Black Hills of South Dakota 75 R90/6, 03 KLR650 . . ____________________________________________________________ Fast, Secure, NetZero 4G Mobile Broadband. Try it. http://www.netzero.net/?refcd=NZINTISP0512T4GOUT2 ------------------------------------ List Sponsors - Dual Sport News: http://www.dualsportnews.com Arrowhead Motorsports: http://www.arrowheadmotorsports.com List FAQ courtesy of Chris Krok: http://www.bigcee.com/klr650faq.html Members Map https://maps.google.com/maps/ms?msid=212558560286766214899.0004d0fa9f1732283bb6f&msa=0&ll=38.522384,-109.489746&spn=6.831383,9.624023Yahoo! Groups Links