The damage of the working device under typical working cycle conditions: For the boom, the earliest damage occurs at the boom ear plate. After analysis, this part is the direct bearer of the force of the stick cylinder, with local stress concentration and the thickness of the ear plate. It is thinner, so it is damaged at the earliest; for the stick, the earliest damage occurs around the pin that is hinged with the boom and inside the pin. After analysis, this part is the connection position between the edge of the stick box and the pin, which is prone to stress concentration. , and is also the position where the stick is subjected to alternating loads, so it is damaged at the earliest.