Lazy Spiral's range of movement

I spent a great deal of time developing the adjusting mechanism for this chair and am pleased with the results. I can understand why other adjusting chairs have either knobs or levers, or the hardware is so large the area beneath the seat must be upholstered to cover it up. The problem is difficult because people range so much in height, weight, and weight distribution. In addition the physics of leaning back is the reverse of sitting up, so the mechanism must function completely different when moving in each direction. This solution takes all this into account plus when the chair is not occupied, the mechanism is sensitive enough to function with just the weight of the seat.