Driven by wind, the machine lifts a 32,000kg weighting load from the water, brings it high up until it releases, falls
and returns into the water with a great splash, while the machine attemps again and again. (Characteristics: floating pontoon
of 40m long, 22m wide, and 5m high with a draught of 3.5 meter; lifting height of 18m above water level; maximal draught of 4.5m;
Cycletime of one day with normal wind-force)
The construction consists of four winglike pillars placed on a floating platform (pontoon).
These pillars support the main axes on which the building cranes are mounted.
The building cranes are interconnected by a grasping mechanism in the middle.
At the extremities of the building cranes large containers are located. These
containers act as countermasses of which the mass is varied by the amount
of water that is inside. When the mechanism is down to grasp the load from
the water, the containers are up in the air. The vertical-axis windmills then
pump water, creating fountains to fill the containers. When the containers
gained sufficient mass to lift the load from the water, the mechanism starts to
move slowly, bringing the load high up into the sky. At the top the mechanism
loses control of the load, the grasping mechanism opens and flips
over by which the load releases and returns into the water. The watermass then is released
from the containers by series of valves. While the mass of the containers is reducing, roaring waterfalls are present
at each side of the machine and the mechanism slowly decents. Everytime the machine returns to the water, it attemps to
lift the load, again and again.
The Watt-mechanism
The kinematics of this machine are based on the well-known mechanism that
James Watt used for his major improvement of the steam engine. This 'double-rocker
linkage' therefore is named 'The Watt-mechanism'. The speciality of this mechanism
is that it has a point in the middle, at about the location of the rock, that
moves on an approximate straight line for a large range of motion. For James
Watt this was important for guiding the piston of the steam engine along a
straight line. For the Sisyphus-machine however, another feature is more important:
the flipping of the grasping link. When the mechanism reaches the top, the
grasping link (the coupler) becomes in line with one of the crane (rocker)
links. Instantanuously, the mechanisms then gains an additional (second) degree
of freedom. In most engineering designs these 'singularities' are problematic
since they are not controllable. For the Sisyphus-machine however this feature
is used in advantage. The complete mechanism is force-driven by the mass of
the containers at each side. These masses act as two co-operating actuators
that combine their forces during the cycle and are able to do the flipping of the grasping link.
