R210-7 R220-3 Excavator relief valve XJBN-00653 hydraulic valve

After the injector is inserted into the cylinder head, the middle O-ring in the three O-rings separates the oil passage in the cylinder head into the oil inlet passage and the oil return passage (the upper part is the oil return passage). Because the oil pressure of the oil inlet passage is higher than that of the oil return passage, when the middle O-ring is broken, the oil in the oil inlet passage will leak into the oil return passage, thereby increasing the pressure in the oil return passage. When the shutdown is turned off, the pressure in the return oil passage will be reversed to the inlet oil passage, so that the oil pressure before the injection metering hole can not be timely reduced to the flame out oil pressure, resulting in flame out difficulties. The severity of the O-ring damage varies with the long and short duration of the flameout. After the fault occurs, it is difficult to determine which cylinder of the injector middle O-ring is damaged, and it is necessary to gradually pull out the injector for inspection until the cause is found. When replacing the damaged O-ring, the O-ring should be correctly installed in the injector groove and cannot be twisted; Should be coated with oil before loading cylinder head; Since the injector is pulled out and reloaded, in general, if there is no very safe measure, the plunger stroke of the injector should be re-adjusted.