I can design a pulley system. It will take 7 pulleys and 1 rope. There will be 4 pulleys on the hood (1 in each corner). There would also be 3 pulleys in the ceiling. It would be strung so with one rope you could raise/lower the whole hood. I was trying to keep cost down by using chains and hooks (1 in each corner).
What I suggest is we desing the chain system, which I can setup on Monday and then (if needed) we can add the pulley system. I will design it, in support of a chain/pulley system. It will be setup that in NORMAL operation the chains will be holding the hood. For maintenance the PULLEY system would be used to raise lower the the hood. The pulleys are about $3/piece ($24 total). I have been designing/building the hood without cost to the zoo as it is my personal contribution to the project. For the pulley/rope system I'll have to think about it, as a donation or recovering the cost.