I bought a car trailer with a lid on it. If for some reason the lid has to come off, I would need at least 2 more persons to do the job.
So I designed a pulley to detach the lid of the trailer on my own. Since the lid is quite heavy (I estimate it to be 60kg) I needed a lot of mechanical advantage (pulling a rope is more difficul than lifting something up - which is why 60kg could be carried with 2-3 persons, but I needed a 16x advantage to be able to manage the rope.
I learned a lot in my first design which I won't share and this is the 2nd design that works perfectly.
It uses a 4mm rope I found in a penny store (in germany 1€ Laden), 7x70 DIN 5299 snap hooks and 6082RS bearings as well as some M6, M8 and M10 bolts. I did not want the parts to get pressed into the thread so I looked for bolt that were as long as the shaft supported the parts with the thread beeing way too long. This is why the thread stick out way too much. I will shorten them with my lathe.
I will probably design parts for smaller pulleys with less advantage if the feedback is high enough.
you will have to flip the non-symmetrical parts with your slicer (i.e. Rollenhalter_R: right version, you need to flip to get the left one)
Since I use Catia V5 for work I designed this pulley in Catia, too. I try to design my parts to be optimized for 3D printing and to have minimal stress while using minimal material.