本文所指的起重机是指履带式、轮式起重机中采用牵拉桁架式吊臂的机种,以下简称起重机。在起重机的回转平台后部有一副龙门架,是由两侧各一只人字形架和一横轴构成的,见 The cranes referred to in this article refer to the types of crawler-type booms used in crawler and wheeled cranes, hereinafter referred to as cranes. There is a gantry at the rear of the slewing platform of the crane. It consists of a herringbone and a horizontal axis on each side. See