I’m not sure these photographs will convey the effectiveness of the system nor am I sure how they will appear on a web page; I have used my ‘phone throughout If they can decipher my text someone better versed than I in fineries of mechanical advantage & velocity ratio will in all probability uncover the networks deficiencies.
My findings however might help & if there were to be a second iteration fresh thinking in certain areas would be considered & implemented.
I had some blocks in stock & so having guessed at what I needed, bought the remainder.
Lesson one, use larger pulleys.
Lesson two use one more pulley in each sheive.
Lesson three, although I’ve created a becket* on my double block by using a cable tie, a triple block with an integral becket would be better.
Lesson four, get sufficient cord. The bits of chain used on the screw eyes are there because I ran out of cordage. In their defence they have been useful for fine tuning heights.
* a becket is the loop on the bottom of a sheive opposite to the main loop tie off. These are very useful tie points at the start of a rig.
The lift is in two stages, having unlatched & unplugged. The first stage takes the top clear of the car, then the front & back rigs are made of on the top wall mounted rail, a second double pulley, which is already on the rope work, is then drawn down & clipped to the lower rail, by doing this the roof is finally lifted to its full hight.
As I have said I can accomplish the operation solo although my wife is usually on hand should it be required.
Any attempt at recreating my system would not be recommended as each installation is room dependant however it might inspire you to look further into the idea.