1. Visual inspection method
For some simple faults, the parts can be checked by means of eye, hand mold, ear, hearing and smelling.
For example, faults such as cracks, oil leaks, looseness and deformation can be found through visual inspection, so that parts can be repaired or replaced in time; Hold the oil pipe (especially the rubber hose) with your hand. When there is pressure oil flow, you will feel vibration. This phenomenon does not exist when there is no oil flow or the pressure is too low. In addition, hand touch can also be used to judge whether the lubrication of hydraulic components with mechanical transmission components is good. Feel the change of component shell temperature by hand. If the component shell is overheated, it indicates poor lubrication; Hearing can judge the fault point and damage degree caused by the damage of mechanical parts, such as the empty suction of hydraulic pump, the opening of overflow valve, the card issuing of components and other faults will send out abnormal sounds such as water impact sound or "water hammer sound"; Some parts will give off peculiar smell due to overheating, poor lubrication and cavitation. The fault point can be determined by smelling.
2. Exchange diagnosis method
This method should be used when there is a lack of diagnostic instruments at the maintenance site or the inspected components are relatively precise and should not be disassembled. First remove the suspected faulty components, replace them with new parts or components of the same model that work normally on other machines, and test them to see whether the fault can be eliminated. For example, the working pressure of the hydraulic system of the working device of a Carter E200B excavator is suspected to be the failure of the main safety valve according to experience, so the main safety valve on the excavator of the same model on the site is replaced with the safety valve. It works normally during the test run, which proves that the suspicion is correct. Although the operation may be troublesome due to the limitation of structure, on-site component reserve or inconvenient disassembly, it is convenient to use this method for small and easy disassembly components such as balance valve, overflow valve and one-way valve. The replacement diagnosis method can avoid the performance degradation of hydraulic components due to blind disassembly. For the above faults, if the suspicious main safety valve is directly removed and disassembled without changing the inspection method, if the component has no problem, its performance may be affected after reinstallation.
3. Instrument measurement and inspection method
The instrument measurement and inspection method is to judge the fault point of the hydraulic system by measuring the pressure, flow and oil temperature of the hydraulic oil in each part of the hydraulic system. In general field detection, the failure of hydraulic system is often manifested as insufficient pressure, which is easy to detect; The flow detection is more difficult. The size of the flow can only be roughly judged by the speed of the action of the actuator. Therefore, in the field detection, the method of detecting system pressure is more used.
