Analysis and Solutions for Low Power and Slow Working Frequency in Large Hydraulic Breakers

I. Clarify the Type of Problem

When addressing issues with a large hydraulic breaker experiencing low power or slow working frequency, it is crucial to first distinguish between insufficient striking force and reduced striking frequency. Although these two problems may occur simultaneously, their underlying causes and solutions differ. Typically:

- **Insufficient Striking Force**: This issue is primarily related to nitrogen pressure. Insufficient nitrogen pressure can lead to inadequate impact force from the breaker; conversely, excessively high nitrogen pressure can obstruct oil intake, causing slow or non-functional strikes.

- **Reduced Striking Frequency**: This is more closely associated with the flow rate of the hydraulic system. If the hydraulic system's flow rate is insufficient, the piston movement will slow down, resulting in a lower striking frequency .

II. Specific Cause Analysis

1. **Abnormal Nitrogen Pressure**

  - The standard nitrogen pressure at the rear of the hydraulic breaker should be 15~17 bar. If the actual measured value is below this range, the breaker may exhibit weak striking force; if it exceeds this range, it can impede oil intake, affecting the striking speed. Therefore, it is recommended to use a dedicated pressure gauge for accurate measurement, ensuring that the nitrogen pressure remains within the appropriate range .

2. **Wear or Damage of Internal Components**

  - Key components such as inner sleeves, outer sleeves, flat pins, and chisels, if deformed or damaged, can obstruct piston movement, leading to difficult strikes. Regular inspection of these components and timely replacement of any damaged parts can effectively prevent such issues .

3. **Improper Relief Valve Settings**

  - The relief valve functions similarly to a fuse in an electrical circuit, protecting the hydraulic system from overload damage. If the relief valve setting is too high, it acts like an unsuitable fuse, losing its protective function; conversely, if the setting is too low, the system cannot build up enough pressure to drive the piston, or it may overflow immediately after starting, manifesting as weak or slow strikes. For this situation, check whether the relief valve has worn out, causing leakage, and confirm that the spring is intact. If frequent adjustments are needed to maintain normal operating pressure, consider disassembling and repairing or replacing the relief valve .

4. **Hydraulic System Pressure Loss (Leakage)**

  - Pressure loss is a common problem in hydraulic breakers, not only affecting system performance but also causing environmental pollution and increasing downtime and maintenance costs. Pressure loss can be categorized into static seal leakage and dynamic seal leakage. Rough handling during assembly, component damage, and improper selection of seals are all major causes of pressure loss. To prevent pressure loss, avoid excessive force during assembly, ensure proper installation of components; regularly inspect the condition of seals and replace aged or damaged ones promptly; choose suitable sealing materials for the working environment, especially dust-proof seals, to minimize contamination of the hydraulic system by external impurities .

5. **Overall Performance Issues of the Excavator**

  - For excavators that experience speed drops and stalling during heavy-duty operations, it is important to rule out whether the issue is due to hydraulic stalling rather than electrical stalling. If there is no black smoke emission and no fault code alarm, it is likely not a problem with the engine's fuel system. In this case, the main pump’s output power may exceed what the engine can provide, causing a sharp drop in engine speed, or even shutdown. At this point, try adjusting different operating modes (such as P, H, or A modes) to observe if stalling occurs. If stalling only happens in G mode, this indicates that the main pump is not correctly sensing the actual output power of the engine. Adjusting the screw on the TVC solenoid valve can improve this situation. Additionally, check the condition of the engine speed sensor and pump pressure sensors to ensure they are accurately transmitting signals .

III. Summary and Recommendations

In summary, the low power and slow working frequency issues in large hydraulic breakers can result from multiple factors acting together. To effectively address these problems, the following measures are recommended:

- Regularly monitor nitrogen pressure to ensure it stays between 15~17 bar.

- Regularly inspect and maintain key components such as inner sleeves, outer sleeves, flat pins, and chisels to prevent performance degradation due to wear or damage.

- Check the settings of the relief valve to ensure it provides effective protection under appropriate conditions, and make adjustments or replacements when necessary.

- Strengthen the maintenance of the hydraulic system to prevent pressure loss, including proper assembly techniques, regular replacement of seals, and selection of suitable sealing materials.

- If the excavator experiences speed drops and stalling during heavy-duty operations, promptly check and adjust relevant parameters to ensure coordinated operation between the main pump and the engine.

By implementing these measures, not only can the efficiency of the hydraulic breaker be improved, but also its lifespan can be extended, reducing maintenance costs and ensuring safe and reliable construction operations.

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