Comprehensive Analysis of Common Excavator Gear Pump Failures and Solutions

1. Insufficient or Zero Output Flow of the Pump

2. Insufficient Output Pressure of the Pump

3. Excessive Noise During the Pump's Operation

4. Severe Overheating of the Gear Pump

In the complex mechanical system of an excavator, the gear pump plays a crucial role. It provides the power source for the various hydraulic actions of the excavator. When a failure occurs, it can severely affect the normal operation of the excavator. This article will explore the common failures of excavator gear pumps and their corresponding solutions in detail.

1. Failure Phenomenon: Insufficient or No Output Flow from the Pump

Possible Causes:

Blocked or Leaking Suction Line: When the suction line is blocked by impurities, dirt, or foreign objects, it prevents hydraulic oil from smoothly entering the gear pump, resulting in insufficient or no output flow. Additionally, if the suction line is leaking air, the pump will intake air during the suction process, disrupting the continuity of the oil and affecting the output flow.
Severe Gear Wear: Prolonged use or operation in harsh environments can cause the gears in the gear pump to wear out gradually. The wear on the gear surfaces increases the gear meshing gap, which increases the internal leakage of the pump, thereby reducing the effective output flow.
Low Pump Speed: If the power source driving the gear pump (such as an engine or motor) malfunctions and operates at a speed lower than the specified value, the displacement of the gear pump will decrease, leading to insufficient output flow.

Solutions:

Check and Clear the Suction Line: Carefully inspect all parts of the suction line and remove any blockages to ensure the line is clear. For leaking areas, use sealant or replace the seals to ensure the line is sealed properly.
Replace Worn Gears: When the gear wear exceeds the specified limits, replace the gears with new ones. Choose gears with the same specifications and reliable quality as the original ones, and install them following the correct installation procedures to ensure proper gear meshing.
Inspect and Repair the Power Source: Use a tachometer to measure the speed of the power source. If the speed is too low, investigate the cause of the malfunction in the engine or motor (such as fuel supply issues, electrical faults, etc.) and repair them to restore the power source to its normal speed.

2. Failure Phenomenon: Insufficient Output Pressure from the Pump

Possible Causes:

Relief Valve Malfunction: The relief valve is a key component that controls the output pressure of the gear pump. If the valve core is stuck in the open position or the spring fails, most of the pump's output oil will flow back to the tank through the relief valve, making it impossible to increase the pressure.
Damaged Seals: Damaged seals (such as oil seals, O-rings) inside the gear pump can cause oil leakage, lowering the pump's output pressure. In high-pressure areas, the impact of damaged seals on pressure is more pronounced.
Insufficient or Contaminated Hydraulic Oil: Low hydraulic oil levels can cause the pump to intake air, affecting pressure build-up. Additionally, if the hydraulic oil is contaminated with particles, it can increase wear on internal components, causing leakage and reducing pressure.

Solutions:

Repair or Replace the Relief Valve: Disassemble the relief valve, clean the valve core and seat, and check the elasticity of the spring. If the valve core is stuck, repair or replace it; if the spring fails, replace it with an appropriate one to ensure the relief valve works properly and maintains stable control of the pump's output pressure.
Replace Damaged Seals: Carefully inspect the seals of the gear pump. For damaged seals, replace them promptly. When installing new seals, ensure the installation position and direction are correct for proper sealing.
Replenish or Replace Hydraulic Oil: Check the hydraulic oil level and add oil as needed. Take an oil sample for testing; if the oil is severely contaminated, replace it with new hydraulic oil and clean the tank and entire hydraulic system to prevent contaminants from re-entering the pump.

3. Failure Phenomenon: Excessive Noise During Pump Operation

Possible Causes:

Air Intake into the Gear Pump: Apart from the suction line leaks mentioned earlier, the presence of a large amount of air bubbles in the hydraulic oil can also cause noise during pump operation. This may be due to poor oil tank design or an improper return oil port position, causing intense agitation and air mixing in the oil tank.
Damaged Internal Components of the Gear Pump: Damage to components like gear surface flaking or bearing damage can cause abnormal vibrations and noise during pump operation. Such damage may result from prolonged overload operation, oil contamination, or improper installation.
Poor Coaxiality Between Pump and Engine or Motor: If the coaxiality between the gear pump and the driving device does not meet the requirements, it can cause additional stress and vibration during operation, resulting in excessive noise.

Solutions:

Eliminate Air Intake Issues: Check the design and return oil port position of the oil tank and make necessary improvements. Install a defoaming device in the tank to reduce air bubbles in the oil. Fix suction line leaks following the methods mentioned earlier.
Replace Damaged Components: Disassemble the gear pump and inspect the condition of gears, bearings, and other components. Replace gears with flaked surfaces and damaged bearings promptly. Adjust gaps and assembly accuracy when installing new components.
Adjust Coaxiality: Use specialized tools to measure and adjust the coaxiality between the gear pump and the driving device to meet the technical requirements. Follow installation standards strictly to ensure secure connections and proper coaxiality.

4. Failure Phenomenon: Severe Heating of the Gear Pump

Possible Causes:

Inappropriate Viscosity of Hydraulic Oil: If the hydraulic oil viscosity is too high, it increases friction resistance during pump operation, causing overheating. Conversely, if the viscosity is too low, it reduces lubrication performance, increasing friction and heat generation.
Excessive Pump Load: When the excavator operates under overload conditions for a long time, such as digging very hard materials or performing frequent high-intensity tasks, the gear pump needs to output more power, generating excessive heat.
Severe Internal Leakage in the Pump: As mentioned earlier, gear wear and damaged seals can increase internal leakage in the pump. The leaked oil circulates within the pump, generating heat through friction and raising the pump body temperature.

Solutions:

Select Hydraulic Oil with Suitable Viscosity: Choose hydraulic oil with appropriate viscosity based on the working environment and equipment requirements of the excavator. Adjust the viscosity grade according to seasonal changes or working conditions to ensure it meets lubrication needs and reduces friction resistance.
Reasonably Control Work Load: Operators should plan tasks reasonably according to the excavator's performance and working conditions to avoid prolonged overload operation. When encountering very hard materials, use suitable digging methods or tools to reduce the load on the gear pump.
Repair Internal Leakage Issues: Address gear wear and seal damage as described earlier to reduce internal leakage and the heating caused by it.

By gaining a deep understanding of common gear pump failures and their solutions, excavator operators, maintenance personnel, and related engineering technicians can more accurately diagnose failures and take effective measures. This not only helps improve excavator efficiency and reliability but also reduces maintenance costs and downtime, ensuring smooth construction operations. Regular inspections, maintenance, and proper operation of the gear pump are essential to prevent failures and keep the gear pump in good working condition.

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