cardan extérieur

CONT: [Les] anneaux de cardan constituent les supports du rotor d'un instrument gyroscopique. On les appelle plus simplement «cardans», car ces supports sont rarement circulaires. La figure 1 illustre un rotor monté sur deux anneaux de cardan, le cardan extérieur étant retenu par un cadre fixe. [...] L'arbre du rotor s'appuie sur des paliers montés dans le cardan intérieur. Ce cardan intérieur repose lui-même sur des paliers montés à l'intérieur du cardan extérieur qui, lui, peut pivoter sur les paliers du cadre fixe (ou du boîtier de l'instrument).

CONT: A conventional gyroscope is a mechanism comprising a rotor journaled to spin about one axis, the journals of the rotor being mounted in an inner gimbal or ring, the inner gimbal being journaled for oscillation in an outer gimbal which in turn is journaled for oscillation relative to a support. The outer gimbal or ring is mounted so as to pivot about an axis in its own plane determined by the support. Hence the outer gimbal possesses one degree of rotational freedom and its axis possesses none. The inner gimbal is mounted in the outer gimbal so as to pivot about an axis in its own plane which axis is always normal to the pivotal axis of the outer gimbal. Hence the inner gimbal possesses two degrees of rotational freedom and its axis possesses one.