对角线的

The two diagonals of a square cross in the centre.

正两条对角线交于正中心。

As the crane is static the mast sections are directly fishplate onto the 4 fixing angles corresponding to the mast type used.

由于该起重机是固定式，其塔节与四根固定角钢呈鱼尾接（译注：即对角线接），而角钢式又与塔身类型相对应。