活动结构
Bascule \Bas"cule\, n. [F., a seesaw.] In mechanics an apparatus on the principle of the seesaw, in which one end rises as the other falls. {Bascule bridge}, a counterpoise or balanced drawbridge, which is opened by sinking the counterpoise and thus lifting the footway into the air.
bascule n : a structure in which one end is counterbalanced by the other (as in a bascule bridge)