Gears and Clockswww.noah.org/science/clock/
This site will help you figure out the gearing.
The power to weight ratio can be looked at like this, There is 1 horse power generated from 550 foot pounds of energy, which is equal to 68.6 gallons of water falling from one foot. This means there is a potential 750 watts in every foot of descent of a mass of that size, double the mass and double the potential. The gearing is based on a few things, first the output desired must be calculated and then the time in which you want that output, then you have to figure out how much mass is required in foot pounds to achieve that specified output and then you determine the height by applying those numbers to how many hours you require energy production. So for every 750 watts it would require the above mentioned 68.6 gallons to fall 1 foot if all things were perfect and there wasn't any resistance ( so factor in the resistance coefficient to get a real idea of power output). Now if you wanted 750 watts for 20 hours it would take 20 feet of drop
to achieve. Now the full 750 watts is only the potential gained after a mass of 550lb. falls from one foot at free fall speeds) It is the force generated by the mass in motion at a velocity achieved from one foot above the ground that delivers the full one horse power, so to make a usable mass generator you have to design it so every foot of descent of the mass is delivered to the flywheel as an impact, so the gearing allows the weight to fall one foot and then engages a drive mechanism to spin the flywheel delivering a constant rotation to the generator. Every impact through out the 20 foot drop delivers one horse power to the flywheel so there is a potential 20 horse power in the 20 feet of height. The trick is harnessing it effectively.