Generally speaking, the centrifuge constitutes a carousel. Inside its closed cabin, the centrifugal force creates an increased weight. Besides serving the purpose of exposing devices to an increased acceleration, the human centrifuge is used in the medical selection and in the training of astronauts and pilots.
An arm of 5 m length carries a cabin that passively swings outwards with increasing acceleration. Accordingly, the resulting force (sum of all forces ) is always brought to bear vertically onto the seat (no lateral forces affect the test person). A three-phase-current motor with a power of 75 KW drives the centrifuge. A fly-wheel with a mass of 1.5 t is set between the motor, the magnetic particle clutch and the gears in order to make possible a steeper increase in acceleration (up to 0.4 g/s). The maximum acceleration possible is approx. 10 g, which corresponds to 10 times the acceleration of the earth.
For example: if a volunteer is to be exposed to an acceleration of 2 g (he will then “weigh” twice as much as with normal acceleration), the centrifuge has to revolve with a velocity of 17.6 revolutions per minute, which corresponds to a velocity of 33.2 km/h inside the cabin. With about 4 g, the untrained person (in a sitting position and without aids like e.g. a pressure trouser) will come up against his limits (impending circulatory collapse).
During the first minutes of the launch of a space shuttle, the astronauts are exposed to accelerations of 4 g max. in a lying position.