一、概述12240柴油机是1968年底开始设计的。1973年在前8台样机试制、试验的基础上,针对“二高一黑”(最高燃烧压力高、排气温度高、冒黑烟)及连杆轴瓦偏磨、烧损,活塞头部焊缝开裂,铸铁活塞裙销座开裂、联结螺钉断,缸套拉伤,气门下陷,气缸盖变形等问题进行了重大修改设计,提高了结构设计的可靠性。样机经100小时性能试验和500小时耐久试 First, an overview 12240 diesel engine is designed by the end of 1968. In 1973 on the basis of the first eight prototypes, the tests were carried out in the light of “two highs and one blacks” (high maximum combustion pressure, high exhaust temperature and black smoke), partial wear on the bearing bush, burnout and piston head welding Crack, cast iron pistons skirt pedestal cracking, broken screw coupling, cylinder strain, valve sag, cylinder head deformation and other issues were major revisions to improve the reliability of structural design. Prototype after 100 hours performance test and 500 hours durability test