continuous loop pulley

[madanitsuj]

I need a loop pulley system like what you might see in a set of blinds to provide a lifting force, except it needs to be able to lift about 100 lbs. Specifically, it needs to be able to use a rope (I've seen mechanisms like this using a chain, but that is too heavy for what I need. I'm pretty sure there's something out there like that, but I can't find it. Can anyone help?

 

[Compositepro]

You cannot find pulleys and rope? Did you check your local hardware store?

 

[bithkits]

Are you asking where to buy one or how to make one or the theory behind it?

@ Compositepro - LOL!

Adriaan.
I am an Engineer/part time student (Mechatronics) from South Africa.
Advice from lecturer: "Be warned - when you go into industry your boss will give you a thousand things to do and he wants them done yesterday!" So far he is right...

 

[Compositepro]

I suspect he was looking for something equivalent to a chain fall hoist that uses a rope instead. The problem would be that an endless loop of chain is easier to make than one of rope, and chain engages with the pulleys like gear teeth so there is no slip possible. No slip is essential for that design to work. The other drawback is that all the weight must be supported by one loop of chain. With a block and tackle three loops of rope will support the load so lighter rope can be used. A block and tackle to lift 100 lbs can be bought for less than $10.

 

[unclesyd]

Here is how it's done on pot haulers. I may stand corrected but you may have to use a long splice in the line for this type to work properly.
Enlarge the picture of the Brutus Hauler.

http://www.go2marine.com/product.do?no=99481F

 

[Compositepro]

Unclesyd, I think you meant your response to be to the rope tow thread.