Howo Mining Truck Gear Pump Failure Symptoms & Troubleshooting

The hydraulic gear pump equipped on HOWO mining trucks supplies oil for the hoisting, steering, brake assist and other hydraulic systems. Once damaged, it will produce a series of typical faults such as mechanical abnormal noise, insufficient hydraulic power, oil leakage and overheating. Combined with the heavy-load, high-dust and high-intensity working conditions of mining trucks, the specific symptoms are as follows:

1. Insufficient hydraulic power and abnormal hoisting movement

This is the core fault manifestation of internal leakage caused by wear of the gear pump. After the gears, bearings and end faces are worn, the internal leakage inside the pump increases sharply, and the oil outlet pressure and flow drop significantly. During operation, the cargo box lifts slowly and weakly. Under heavy load, it may even fail to lift or stall and drop halfway during lifting. Lifting may barely work under no load, while the fault becomes obvious under full load. Some vehicles may have the cargo box automatically fall back and fail to hold pressure after fully lifted, seriously affecting unloading operations. If the gear pump shaft breaks or gears jam, there will be no hydraulic oil output at all, and the cargo box cannot be lifted completely.

2. Obvious abnormal noise and increased noise level

A normally working gear pump only emits a low and steady hum. After damage, abnormal noise is very noticeable. When the gear meshing surfaces are worn, gear teeth break, bearings are damaged, or hard impurities enter the pump chamber, you will hear sharp whistling, metal friction sound and impact noise. In case of air intake or cavitation inside the pump, gurgling bubble sounds and continuous squealing can be heard. The abnormal noise is slight at idle speed but rises sharply when accelerating or working under heavy load, accompanied by obviously increased vibration of the whole machine.

3. Hydraulic oil leakage and cross oil leakage

A damaged gear pump may have oil leakage at multiple positions due to aging of oil seals, lip damage, failed end-face sealing of the pump body or cracked housing. The most common issue is oil leakage from the shaft skeleton oil seal. Oil stains appear on the pump surface and joints, and the hydraulic oil level keeps dropping with continuous leakage. In severe cases, oil seeps from the pump end face or leaks through sand holes on the housing. Meanwhile, failed internal seals cause cross-flow of oil, resulting in disordered hydraulic circuit and intermittent jitter of movements.

4. Abnormally high temperature of pump body and hydraulic system

Excessive internal wear, large clearances, severe internal leakage, gear jamming or abnormal load will lead to repeated compression and friction heating of hydraulic oil. After failure, the pump body of the gear pump becomes burning hot after short-time operation, and the oil temperature of the hydraulic tank rises rapidly above normal working range. High temperature further accelerates seal aging and oil deterioration, forming a vicious cycle and eventually causing failure of the entire hydraulic system.

5. Abnormal vehicle operating conditions and secondary faults

For the working conditions exclusive to HOWO mining trucks, damage to the gear pump may also cause associated problems. On some models, the gear pump also serves as an auxiliary fuel supply pump. If the pump is damaged or the shaft breaks, the vehicle may stall or fail to start normally. It can run briefly with the electric pump and will stall immediately once the electric pump is turned off. Long-term faults allow a large amount of metal impurities to mix into hydraulic oil, contaminating the whole hydraulic circuit, blocking filter elements, wearing oil cylinders and control valves and triggering secondary hydraulic failures.

6. Pump jamming and abnormal rotation

When gears inside the pump seize up, bearings lock, or impurities jam the gear pair, the gear pump rotates sluggishly with excessive resistance. In mild cases, the engine struggles under load and idles roughly. In severe cases, the pump locks solidly, completely paralyzing the hydraulic system and even damaging the engine transmission structure.