目前,四轴货车上使用的上心盘已近十种,但其中大部分是旧型的,运用可靠性低。1970～1971年生产的以圆锥腰代替外筋的上心盘,运用可靠性虽较高,但在运用总数中所占的比重还不大。因此每年都有大量的上心盘需要修理以致报废。各铁路局一些车辆段对于上心盘技术状态的调查表明,上心盘的损坏率与报废率跟车种有关:罐车为56％与7.5％;敞车为27％与3％;棚车为9％与0;平车为3.5％与0。上心盘疲劳裂纹的主要原因是危险截面的工作应力太高。裂纹绝大多数发生在外筋 At present, there are nearly 10 types of center plates used on four-axle trucks, but most of them are old type ones, and the reliability of their use is low. Produced by the 1970-1971 conical waist instead of the outer rib on the center of the plate, although the use of high reliability, but the proportion of total use is not large. So every year a large number of need to repair the heart plate so scrapped. Investigation of the technical status of the center tray by some depots of railway administrations showed that the damage rate and scrap rate on the center tray were related to vehicle types: 56% for tankers and 7.5% for gondolas; 27% and 3% for gondola cars; and 9% for box cars. With 0; flat car is 3.5% with 0. The main cause of fatigue crack on the heart plate is the working stress of the dangerous cross section is too high. The vast majority of cracks occurred in the external ribs