Improper modification of the broken hammer connection resulted in excavator stalling

A customer in TangshanSK200-6After the excavator is started, the engine stalls; Any slight operation of the engine will extinguish it;

Cause analysis:

Due to long-term use of the breaker hammer, the regulator of the machine has worn out and become stuck, often resulting in slow movement and deviation during travel;
After purchasing the hydraulic pump assembly for replacement, the user has been using it for half a year and has been operating slowly, often experiencing stuck driving conditions;
Check the service diagnosis, there is a 28MPA load on pump P1 after startup, and there is no abnormality on pump P2; Determine if there is an abnormality in the hydraulic system; Pulling out the P1 neutral cut-off PSV harness, the fault did not improve; Remove P2 neutral cut-off PSV, start the engine with stable speed, and the abnormal load disappears;
Based on this, it can be concluded that: 1. The main computer board received abnormal signals from relevant sensors, resulting in the issuance of abnormal commands to cause P2 to neutral and cut off the PSV action; But the load exists in the P1 pump. It was determined that the high-pressure sensor was mistakenly inserted. After checking and confirming that the high-pressure sensor and P1/P2-PSV were inserted correctly, the circuit was ruled out. As the hydraulic pump of the machine had been replaced, it was found that the P1/P2 working oil pipe was connected incorrectly to the multi way valve during inspection; Restore the oil pipe, connect the relevant wiring harness, and after starting, the load changes to P2 pump;
2. At this point, it is determined that there is an abnormality in the feedback signal of the low-pressure sensor; Causing the main computer board to issue an incorrect command, resulting in the neutral cut-off action of P2; Due to the installation of a breaking hammer on the machine, special attention was paid to checking the signal of the low pressure sensor of the breaking hammer. The service diagnosis showed that the feedback signal value of the low pressure sensor of the breaking hammer was slightly larger by 0.6V. It was found that the sensor was a type 6 machine sensor, which did not match the 6E sensor plug. The user modified the connection themselves, and finally confirmed that there was an abnormality in the wiring, which caused the computer board to receive abnormal signals and mistakenly instructed P2 to perform neutral cut-off action before holding the car.

Handling method:

1. Restore the normal working oil pipe connection, reconnect the broken hammer connection and restore it;
2. During the repair process, carefully analyze the abnormal content based on service diagnosis, infer possible causes of faults, and check and eliminate problem points one by one;