Yep, a pulley (snatchblock) doubles the power or halves the effort. It also doubles the amount of cable that has to be played out. Each time you add a pulley it halves the previous amount of pull. 1 pulley, 1/2 effort, 2 pulleys, 1/4 effort, etc. I was watching a staged tank winching. They used a heavy rope and had something like 16 pulleys altogether. They pulled the tank out by hand with a bunch of Army guys. You have to have alot of rope and patience using that kind of method though.

 

Is it double the power ONLY because of double the line??

 

It's something to do with the pulley itself more than the amount of rope. The use of the pulley(s) necessitates the use of more rope.

 

<div class="FTQUOTE"><begin quote>Originally posted by: MooseHenden

It's something to do with the pulley itself more than the amount of rope. The use of the pulley(s) necessitates the use of more rope.</end quote></div>

Thanks for clearing that up. I have always wondered if it was just because you have to use double the line.

 

OMG don't they teach this in school any more ??

 

Public school, maybe not. I saw it in the books my boys use for homeschooling. I learned about it through examples and physics.

 

keep in mind,as noted above, it doubles the pulling power, but if your line is only rated for 1500 lbs. it could snap injuring you or someone else. when using a ****** block, you have to be sure your line can handle the pressure. you might have gotten a good price on the winch, but you should have spent the little extra for a heavy model.

 

Physics 101: I'll keep this in the simplest terms possible....
- A ****** block doubles the pulling power because at the motor (cable reel) it is still taking in the same amount. However, because it is doubled back to the object being pulled, it is pulling in the same amount of cable at HALF THE SPEED; hence double the pulling power. It's "mechanical advantage". Sit on the ground and tie a rope to a tree. Now pull yourself towards the tree with the rope. Then, attach a pulley (****** block) to the tree. Tie one end of the rope to your ankle, and pull on the other end. For the same amount of rope as you pulled in the first time, you will move half as far and will be using half the effort.

And... if your line is rated for 1,500lbs and use a ****** block and pull way 2,000lbs it will not break. You are "doubling" the line so in theory it will be twice as strong. However, because the force of firction at the pulley, it's not quite twice as strong. For arguments sake though, you will be fine.

 

Perfectly explained. Thks

 

I always thought that it was getting married . . .lol