lifting mechanism

i have been looking into what type of mechanism to use to lift the load. the two most feasible methods would be either a hydraulic jack or a pulley system, both of which will have to be simple to use so that any member of the general public would be able to use it.
A bottle jack can be used however the downfall to this is that the angle that it is used at cannot be more than 5 degrees and on rough terrain this would be hard to keep to, they can however lift upto 12 tons which would be more than enough.
I have found a brilliant system that might work to incorporate what is called a farmers jack onto a tripod design. this works by basically the jack pushing up on itself by this we can attach it to the bar that will be attached to a hook lifting the bar.
I sourced my information on the jacks from (http://www.ttclifting.co.uk/hydraulic/hydraulic_mechenical_jacking_division.html).
Although a jack is probably an efficient method a pulley system would be easier to design and would be easily adjustable. Even though it would need more strength it would also be easily replaceable for parts.