Vertical lift: Prototypes #4, 5, 6

(See also prototypes 1 through 3.) Prototype #4: Quad-Pulley Elevator (axled) A fundamental shift in design vis-à-vis prototypes 1-3, lift #4 raises a rectangular platform via four corner pulleys. Design: 1/2" steel pipe structure. Flanges bolted to pulleys for pipe framework attachment. To minimize drive complexity, a single 12V/2000lb winch ($50, Chicago Electric model 92860) draws all four pulleys simultaneously via a pair of axles. Several additional pulleys redirect cable f...