MA for z -rig

[Dagger]

is this correct ?

 

[TimMc]

1:1

 

[Crisp image]

yes the "Z" rig is a 3:1 mechanical advantage. Theoretically. you need to consider friction coefficient (5% per pulley for a start)
I use these all the time to lift heavy lights into place where they are rigged outside a handrail on bridges. It means I can safely bring the fixture up and hang it without fer of dropping it getting it over or through the handrails.
I also use a capture device so if I let go of the rope it does not plummet to the ground.
Regards
Geoff

 

[brucek]

How would this change if the rope to the weight is attached with a pully instead of a fixed point? Would the rope though the weight (marked in red in the diagram) become a 2:1 resulting in a total 4:1?....or am I just completely off?

 

[Dagger]

something like this ??

 

[Crisp image]

View attachment 24988something like this ??

If you did this I think you will only turn the rope in a circle and not get much more than 2:1 i could be wrong but ooking at it by pulling on the rope you would move the pulley to the top of the picture and then it has no effect al all.