Excavator pump plunger and cylinder "killed" Troubleshooting: a HE-280 excavator, overhaul and replace the hydraulic pump cylinder and plunger, the hydraulic pump does not work and accompanied by abnormal sound. Disassembly found that the plunger and cylinder stick together, was "killed" state. Metallographic analysis of the cylinder block and the plunger confirmed that retained austenite was transformed into martensite, and the lower the temperature, the greater the amount of change. In the cold season, the residual transformation is completed in a very short period of time, causing the piston to "bite to death" due to its instantaneous increase in volume. To this end, can be measured with a special measuring tool hydraulic cylinder and plunger at room temperature with the gap; the cylinder and the plunger were cold treatment, that is placed in the -50 ~ -60 ℃ place, remove after 30 min; Grinding the plunger grinding to room temperature with the size; on the plunger surface laser quenching; with a special polishing paste on the piston surface and then polished, re-installed troubleshooting.