The key to the system software using hydraulic transmission in the excavator is the dominant hydraulic transmission system, the rotary hydraulic transmission system, the walking hydraulic transmission system, the hydraulic transmission system of the working equipment, etc. It has compact structure, flexible posture, stable operation, convenient actual operation, etc. Advantages, the hydraulic transmission system must use gear oil as the driving force material, which will cause leakage due to damage to the internal electronic components, and accompanied by common faults such as over-temperature and fatigue during work.
The emergence of common faults in hydraulic transmission is sudden and secretive, and there are many electronic devices involved, which makes it difficult to detect and clear the fault. Therefore, when repairing the hydraulic transmission system, it is necessary to understand the principle and properly analyze the common faults. For this reason, the quality of overhaul can be ensured basically.
In this article, we take the common failures of the PC200-5 excavator as an example, introduce the principle of hydraulic transmission in detail, and analyze the diagnosis and removal methods of its mechanical failures.
Principle of hydraulic drive system of PC200-5 excavator
The hydraulic drive system of the PC200-5 excavator is composed of some basic control circuits and auxiliary tool control circuits. They include the working control circuit, the pressure limiting control circuit, the throwing control circuit, the buffer control circuit, the throttle valve speed change and the throttling. Valve speed limit control loop, walking speed limit control loop and pilot valve control circuit, etc. The key of its electronic components is composed of the working pump, the gasoline supplement pump, the main pressure regulating valve, the multi-way valve, the valve, the rear arm hydraulic cylinder, the forearm hydraulic cylinder, the bucket hydraulic cylinder, the automobile fuel tank and related pipelines.
In the whole process of the hydraulic transmission system of the PC200-5 excavator, the gear oil is pumped in from the bottom of the automobile fuel tank according to the oil filter during operation, and the gear oil with a certain working pressure is output from the gasoline pump into a series of series. Multi-way valve. According to the rocker-→ pilot valve-→ valve in operation to maintain the relative posture, the system software limits the total working pressure of all system software according to the total valve on the main oil passage, and the valves of the fuel pipes in each group of work are opposed to the relative fuel pipes. Overpressure protection and oil replenishment function.
On-the-spot diagnosis of hydraulic machine failure of excavator
The diagnosis on the spot requires that the maintenance staff have certain hydraulic transmission expertise and social experience. Before failing to detect a new type of failure, you should carefully read any application maintenance instructions in the article to have a basic understanding of the hydraulic transmission system of the machine user. At this stage, the hydraulic transmission system of small and medium-sized excavators is basically composed of two parts: the main working fuel pipe and the main control fuel pipe.
According to reading the technical documents of the article, grasp the basic parameters of the system software, such as the opening working pressure of the main valve, the leading control working pressure and the total flow, etc.; understand the circuit schematic diagram of the system software, and grasp the responsibilities and markings of the components in the system software Analyze the function of each control circuit; also have a certain grasp of the structure and principle of each hydraulic component; analyze the cause of a common failure; compare the equipment to grasp the belonging of each hydraulic component Location, and the way of interface between them.
In actual diagnosis of common faults, the order of "external to internal, targeted" should be followed, and the cause of a common fault should be investigated one by one.
Ways to diagnose common faults on the spot
The key way to diagnose hydraulic machine faults on the spot is still the work experience diagnosis method. The work experience diagnosis method is that the maintenance staff use the basic knowledge and accumulated work experience that they have grasped, integrate the actual situation of the machine, and apply the method of "asking, watching, listening, touching, and testing" to quickly diagnose the location of common faults. And a way for sake.
