07-12-2008, 12:56 AM
Quote:I believe the idea was to secure the basic A-frame using guy ropes. By loosening the guy ropes, the crane could move its load forwards (and backwards) over a short distance. So some limited fine-tuning was possible.
That is how I understand it, too.
Quote:The swivelling cranes used on the quayside followed a different design. Here, a single upright was secured by four guy ropes. A carchesion near the top allowed a boom, or spar, to extend outwards in any direction.
The existence of ancient (harbour) cranes with swivelling mechanism is news to me. To what source(s) do you refer exactly? Perhaps Marsden was only conjectural here.
Stefan (Literary references to the discussed topics are always appreciated.)
