open stacker project

[davidbrady]

Greg,

I don't want to steal all the fun design work away, but if you indulge me for a moment. In the interest of weight savings, the hand crank gear reduction transmission can all be done with chains and sprockets. For example, if the differential is around 4:1 and the worse case torque on the rotating cam is 5000 ft-lbs (just one Razor loaded, so no counterbalance) then a 100:1 gear reduction will bring the force needed on a 2 ft long crank arm down to 25 lbs, and at 100:1 it'll only take 25 cranks to travel the 45 deg or so of full motion. We already have 4:1 at the differential so now we need an additional 25:1. We can use two 5:1 stages. This requires one intermediate shaft. From the crank to the intermediate shaft we'll get 5:1, and from the intermediate shaft to the differential we'll get another 5:1. The first stage chain will have a max tension of around 250 lbs so all of the first stage can be done with bicycle components including a bicycle lower bracket for the crank pivot. In fact, an extended pedal crank arm of a bicycle can be used for the hand crank. The second stage will have a max chain tension of 1250 lbs so a motorcycle chain and sprocket assemblies might be more appropriate. If you want you can include a full bicycle lower bracket assembly with pedals and crank arms and you can crank it with your feet like riding a bike! All of this can be very cheap, compact, and light' plus when you want to get a workout in you can use it as a stationary bicycle! LOL!

Give me a lever long enough and I can move the world...