The main method of faults in the hydraulic wheel loader system is still to undergo the diagnosis method. The experience diagnosis method is a method for repair personnel to use the theoretical knowledge and accumulated experience that they have grasped, combined with local practice, to quickly diagnose the location and cause of the fault.
1. Look
"Look" is to check the working status of the hydraulic system through the eyes. Such as whether the amount of oil in the fuel tank meets the requirements, whether there are bubbles and discoloration (the noise, oscillation and crawling of the machine are often related to a large number of bubbles in the oil); the leakage of oil at the sealing part and the pipe street; the pressure gauge and The change of the indicated value of the oil temperature gauge during the operation; whether there is damage to the faulty part, the connection is gradually falling off and the fixing parts are loose. When there is a problem with hydraulic oil leakage, after removing the insufficient or uneven torque of the tightening bolt, before replacing the oil seal that may have been severely worn or damaged, it should also be checked whether the pressure exceeds the limit. When installing the oil seal, the type and quality of the oil seal should be inspected and assembled accurately.
2. Listen
"Listen" is to check the hydraulic system for abnormal sound with your ears. Normal machine operations have a certain rhythm and rhythm, and remain stable. Therefore, be familiar with and grasp these rules, and maintain stability. Therefore, by familiarizing and grasping these rules, you can accurately diagnose whether the hydraulic system is operating normally; at the same time, according to the changes in rhythm and rhythm, and the components produced by abnormal sounds, you can determine the faulty parts and the faults. The location of the attack and the degree of damage.
For example, the high-pitched squealing noise is usually sucked into the air; the "chirp" or "giggling" sound of the hydraulic pump is often the damage of the pump shaft or bearing; the directional valve emits a "chirping" sound, which is the stem opening Insufficient degree; the thick "click" sound may be the sound of overload valve overload. If it is cavitation, it may be that the oil filter is blocked by dirt, the suction pipe of the hydraulic pump is loose, or the oil level of the fuel tank is too low.
3. Try
"Trial" is to operate the fulfillment components of the machine's hydraulic system to determine the location and cause of the fault from its operating conditions.
(1) Full test. According to the design function of the hydraulic system, test one by one to determine whether the fault is in some areas or in the whole area. If the operation of the whole machine fails or is weak, you should first check whether the pilot operating pressure is normal, whether the clutch (coupling) slips (loose), whether the engine power is satisfied, whether the amount of hydraulic oil is sufficient and the sealing condition of the hydraulic pump inlet. The faulty symptom of the loader is only the active descent of the boom, then the faulty cause may be in the oil path of the reversing valve, overload valve or hydraulic cylinder, not related to the hydraulic pump and the main safety valve.
(2) Exchange test. When only a certain circuit or a function is lost in the hydraulic system, it can communicate with the oil circuit of the same (or related) function to further determine the faulty location. For example, the loader has two independent working circuits, and each circuit has its own components.
4. Touch
"Touch" is to use the active finger touch to check whether the piping or components of the pressure system are oscillating, impacting, and the oil temperature rise is abnormal. If you touch the pump casing or hydraulic parts by hand, you can determine whether there is abnormal temperature rise in the hydraulic system according to the degree of heat and cold, and determine the cause and location of the temperature rise. If the pump casing is overheated, it indicates that the pump has a severe leak or that air has been sucked in. If you feel abnormal oscillation, it may be that the rotating parts are not well balanced, the tightening screws are loose, or there is gas in the system.
