A 20t crawler excavator was found to have the boom falling automatically. Automatic boom falling is one of the more common excavator failures. Many people think that the oil seal will cause failure only if it is worn seriously. Because the cylinder oil seal will wear and age during use. If the two-way boom falls automatically, the oil seal is likely to be damaged. It can be determined by raising the boom and then disconnecting the boom rod cavity to observe whether hydraulic oil flows out. In fact, the main reason for the boom to fall automatically is the boom reversing valve and overflow valve. Only worn piston seals will not cause the boom to fall.
