Analysis of Fault Characteristics of Construction Machinery and Fault Diagnosis Techniques

The stages and characteristics of faults in construction machinery

(1) Fault characteristics of construction machinery in the initial stage of use. During the initial stage of use of construction machinery (equivalent to the running-in period), the failure rate decreases from high to low (descending curve). The failure rate in the initial stage of use is related to the manufacturing or maintenance quality and the usage during the running-in period. If the manufacturing or repair quality of construction machinery is high and it can be used and maintained correctly. Then, the initial failure rate will be low. Otherwise, the early failure rate will be high. Early faults are often caused by loose or detached connecting bolts. Loose or loose pipe joints: Residual metal shavings or casting sand can easily clog oil passages or get stuck in the friction of relative motion, scratching machine parts (such as the actuator cylinder in the hydraulic system), causing oil leakage. The adjusted clearance or pressure changes, making the machine parts unable to perform the specified capacity. Some joints may leak water, oil or air due to loose bolts.

(2) Fault characteristics of construction machinery during the normal operation stage. After the running-in period of construction machinery is over, it enters the normal use stage. During this stage of operation, construction machinery generally does not experience malfunctions as long as it is maintained and used correctly in accordance with regulations. Even if malfunctions occur, they are random (such malfunctions are concealed and difficult to detect during maintenance or inspection), so the failure rate is very low, with a gentle and slightly rising curve. If construction machinery malfunctions during its normal service life, it is mostly accidental or caused by improper use and maintenance.

(3) Fault characteristics of construction machinery when it is approaching the major overhaul period. When the operation of construction machinery approaches the major overhaul period, the wear and tear of each component increases. The technical condition has deteriorated. The characteristic of faults at this stage is a high failure rate. Moreover, most of them are caused by excessive wear and aging of parts, and the phenomena of blockage, leakage and damage in the oil circuit occur frequently.

(4) Fault characteristics of construction machinery in different seasons. The failure rate of construction machinery is related to the season. When using machinery in low temperatures during winter, the failure rate is higher than that in summer. For instance, the fuel supply system often has poor atomization in winter due to low temperatures. The fuel is prone to solidification, causing fuel line blockage and making it difficult to start. Or faults such as the engine stalling while running; Poor fluidity of lubricating oil accelerates the wear of machine parts. Battery leakage can cause the engine to be difficult to start, unreliable braking, and abnormal liquid transmission, etc.