space between legs腿间空间例：Gantry crane is the main handling machinery in the open-air container yard, the U-shape metal structure of gantry crane is the preferred one, because of its good force state and large space between the legs.门式起重机是露天站场的主型装卸机械，其U型金属结构受力状态好，过腿空间大，是集装箱门式起重机的首选结构型式。
