a contrivance, typically consisting of rings pivoted at right angles, for keeping an instrument such as a compass or chronometer horizontal in a moving vessel or aircraft.（在航行的船只或飞机上使罗盘等仪器保持水平位置的）常平架, 平衡环
a contrivance, typically consisting of rings pivoted at right angles, for keeping an instrument such as a compass or chronometer horizontal in a moving vessel or aircraft.（在航行的船只或飞机上使罗盘等仪器保持水平位置的）常平架, 平衡环