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August 13, 2020
Excavator maintenance: crawler excavator can't start suddenly
Description of fault information feedback: The customer reported that the engine could not be started when the excavator was in operation for 1519 hours.
On-site fault description: On-site test machine, unable to start, and the starter does not turn.
Analysis of the cause of the failure: Since the starter does not turn, the possibility of the engine can be ruled out, so that the range can be narrowed to the range of the electrical starting system. possible reason:
(1) The battery voltage is insufficient;
(2) Start relay failure;
(3) Start protection relay failure;
(4) The key switch fails;
(5) Starter failure;
(6) Line failure.
(1) Check the battery voltage of the storage starter, the starter B terminal voltage of 12.5V is normal;
(2) Turn the key switch at the starting position to measure the S terminal of the starter without voltage, and look up according to the schematic diagram;
(3) When it is in the starting position, there is voltage at the A terminal of the starting relay and no voltage at the B terminal, indicating that the starting relay is not working;
(4) Turn the key switch on the starting position, measure the 14# no voltage of the starting relay signal, and continue to look up;
(5) When the key switch is in the starting position, measure 111# with voltage and 14# without voltage at the starting protection relay, indicating that the starting protection relay may be in working condition;
(6) Measure the starting protection relay control signal (24#) without voltage and normal, indicating that the starting protection relay is faulty.
Inspection result and treatment method: the fault is eliminated after replacing the starting protection relay.