Moreover, the undercarriage offers increased stability because of its long crawlers while maintaining a limited swing radius for the upper structure.
此外,由于履带长,底盘系统提供了更高的稳定性,同时保持了上部结构有限的回转半径。
英语百科
Upper structure
In jazz music, the term upper structure or upper structure triad refers to a voicing approach developed by jazz pianists and arrangers defined by the sounding of a major or minor triad in the uppermost pitches of a more complex harmony.