Created on:2021-09-28 14:21

Hydraulic fault diagnosis and maintenance of hoisting and transportation equipment_ Scraper hydraulic system failure

Hydraulic fault diagnosis and maintenance of hoisting and transportation equipment_ Scraper hydraulic system failure

CT-500HE miniature electric scraper imported from France is a full hydraulic ore shovel equipment. Four wheel drive, bucket capacity of 0.38m3, effective load of 600kg. The hydraulic system is the heart of the whole equipment. The static pressure pump and are driven by the motor to realize axle steering, bucket lifting, loading and unloading, shoveling and cable winding. The equipment has high working efficiency and flexible steering. Due to untimely maintenance, some hydraulic faults occurred in the scraper.

(1) Fault analysis of hydraulic system

The hydraulic system working circuit of CT-500HE electric scraper mainly includes static pressure circuit (including traveling circuit and auxiliary working circuit) and hydraulic circuit (shovel working circuit, steering circuit, cable winding circuit, etc.).

Fault phenomenon: power transmission inspection, trip within the delay time (3S), and the motor starts. Disconnect the protection system and start the motor (without tripping). The axle steering part, shovel lifting part and cable winding part work normally, but the scraper still can't walk. From the analysis of fault phenomenon, the fault may be in the static pressure circuit.

Detect the static pressure traveling circuit. As shown in Figure n, the pressure of valve 1 and valve 3 is P1 = 42MPa, and they work normally. Detect the auxiliary circuit. The pressure P2 = 0.5MPa, which is less than the normal working pressure (1.0 ~ 1.6Mpa). The fault may be in the auxiliary circuit.

N.jpg

Analyze the auxiliary circuit. From the function analysis of the auxiliary circuit, when the pressure is lower than the normal working pressure, the relay (safety protection device) will act and trip within the delay time. At the same time, the hydraulic brake can not be opened, resulting in the failure of the scraper, which is consistent with the fault phenomenon. Therefore, it can be determined that the fault is caused by the auxiliary circuit pressure. The reasons for the decrease of auxiliary circuit pressure are: ① valve 2 (1.6Mpa overflow valve) fault; ② Leakage of auxiliary pump, brake and oil circuit; ③ The oil level is low.

(2) Troubleshooting

Remove valve 2 and open it. It is found that the valve core is stuck by black colloid and cannot be closed tightly, resulting in leakage and reduction of auxiliary circuit pressure.

Clean the overflow valve and filter screen, replace the hydraulic oil, reassemble, test run, and the machine returns to normal.

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