1. Visual inspection
For some simple faults, parts can be inspected by means of sight, hand model, ear hearing and smell.
For example, visual inspection can find fault imaginations such as rupture, oil leakage, loosening and deformation, which can be repaired or replaced in time; hold the oil pipe (especially the hose) with your hand, there will be vibration when pressure oil flows through There is no such phenomenon when there is no oil flowing 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 parts is good. Feel the temperature change of the component housing with your hand. If the component housing is overheated, it means that the lubrication is poor; the ear can judge the mechanical parts The fault points and the degree of damage caused by damage, such as hydraulic pump suction, overflow valve opening, and component card issuance, will produce abnormal sounds such as water impact sound or "water hammer sound"; some parts will be due to overheating, poor lubrication and cavitation The odor is emitted for other reasons, and the fault point can be determined by sniffing.
2. Swap diagnosis
This method should be used when there is a lack of diagnostic instruments at the maintenance site or the components being inspected are relatively precise and should not be disassembled. First, remove the suspected faulty component, and replace it with a new one or a component of the same model that works normally on other machines for testing, and see if the fault can be eliminated to make a diagnosis. For example, the working pressure of the hydraulic system of a Caterpillar E200B excavator is suspected to be a failure of the main safety valve according to experience, so the main safety valve on the same model of the excavator on site was exchanged with the safety valve. Works normally, confirming the suspicion is correct. Diagnosis of faults using the swap diagnosis method, although it is limited by factors such as structure, on-site component storage or inconvenience in disassembly, may be more troublesome to operate, but it is small and easy It is more convenient to use this method for disassembled components. The swap diagnosis method can avoid the performance degradation of hydraulic components caused by blind disassembly. If there is no need to check the replacement for the above faults, directly remove the suspicious main safety valve and dismantle it. If the component has no problems, it may affect its performance after installation.
3. Instrument measurement inspection method
The instrument measurement inspection method is to determine the fault point of the system by means of the measurement of the pressure, flow and oil temperature of each part of the hydraulic system. In the general on-site inspection, the failure of the hydraulic system is often manifested as insufficient pressure, which is easy to detect; while the detection of the flow rate is more difficult, the size of the flow rate can only be roughly judged by the speed of the actuator. Therefore, in on-site testing, more methods of detecting system pressure are used.
