Troubleshooting Hydraulic Pulsation Issues in the PC160-7 Excavator

[MikePhua]

Hydraulic systems are the lifeblood of many heavy machines, and any issue within the system can lead to reduced efficiency, increased wear and tear, or even catastrophic failures. One such issue that often plagues hydraulic excavators, including the Komatsu PC160-7, is hydraulic pulsation or jerking. This phenomenon is characterized by an irregular and jerky motion within the hydraulic system, which can affect the operation of the machine and even cause discomfort for the operator. In this article, we’ll explore the common causes of hydraulic pulsation in excavators like the PC160-7, why it happens, and how to resolve it.
What Is Hydraulic Pulsation?
Hydraulic pulsation refers to the erratic and inconsistent movement of hydraulic fluid through the system, which leads to uneven performance of the excavator's hydraulics. This pulsation can result in jerky, jumping motions in the boom, arm, or bucket movements, often making the machine difficult to control. The pulsations may not only be an inconvenience, but they can also lead to long-term damage to the hydraulic components due to stress and wear.
Pulsations in hydraulic systems can occur in various forms, including:

• Continuous Jerking: The hydraulic actuators, like the boom or bucket, may continuously jerk back and forth.
  
• Irregular Pressure Fluctuations: The hydraulic system may experience pressure surges, leading to sudden spikes in force, causing the machine to behave erratically.
  
• Unsteady Flow: Fluid flow may become inconsistent, leading to uneven power delivery, making tasks like digging or lifting challenging.
  

Common Causes of Hydraulic Pulsation in Excavators
Several factors can contribute to the hydraulic pulsation issue in the PC160-7 or any other similar excavator. Understanding these causes is the first step in troubleshooting and resolving the problem.
1. Air in the Hydraulic System
Air trapped within the hydraulic fluid is one of the most common causes of hydraulic pulsation. When air enters the hydraulic system, it compresses and decompresses as the hydraulic fluid moves through the system, causing uneven pressure and flow. This leads to the characteristic jerky movement of the hydraulic cylinders.

• Symptoms: You may hear a “whining” noise from the hydraulic pump, and there will be noticeable jerking in the excavator’s movements.
  
• Cause: Air can enter the system due to loose or damaged seals, improperly filled hydraulic tanks, or damaged hoses.
  
• Solution: Bleed the hydraulic system to remove any trapped air, and inspect seals and hoses for leaks.
  

2. Low or Contaminated Hydraulic Fluid
Low hydraulic fluid levels can create a variety of problems, including pulsation. Similarly, if the hydraulic fluid is contaminated with dirt, water, or other particles, it can cause the hydraulic pump and valves to malfunction.

• Symptoms: Unstable operation and noisy hydraulics. The pump may struggle to maintain consistent pressure.
  
• Cause: Fluid levels may have dropped due to leaks, or the fluid may have become contaminated due to poor maintenance practices.
  
• Solution: Check and top up the hydraulic fluid. If contamination is suspected, replace the fluid and filters. Regular fluid changes are essential to maintaining the health of the system.
  

3. Faulty Hydraulic Pump
The hydraulic pump is responsible for pressurizing the fluid and creating the necessary flow to power the actuators. A malfunctioning or worn-out hydraulic pump can lead to inconsistent fluid pressure, causing pulsations in the system.

• Symptoms: Jerking or pulsation in the machine’s movements, especially when performing heavy tasks like lifting or digging.
  
• Cause: Internal damage to the pump, worn-out gears, or faulty pressure relief valves.
  
• Solution: Inspect the hydraulic pump for signs of wear or damage. If necessary, replace the pump or any faulty components.
  

4. Clogged or Faulty Hydraulic Filters
Hydraulic filters are designed to trap dirt, debris, and contaminants that could damage the system. If these filters become clogged or fail to operate properly, they can restrict fluid flow, leading to pressure fluctuations and pulsation.

• Symptoms: The excavator may experience a loss of power, and the hydraulic system may overheat due to restricted fluid flow.
  
• Cause: Dirty or clogged filters reduce the efficiency of the system and may cause uneven hydraulic fluid delivery.
  
• Solution: Check the hydraulic filters and replace them regularly as part of your routine maintenance. If the system is still jerking after filter replacement, the problem may lie elsewhere.
  

5. Valve Malfunctions
Hydraulic valves control the direction, flow, and pressure of the fluid within the system. If these valves malfunction, they can cause pressure imbalances or flow restrictions, leading to hydraulic pulsation.

• Symptoms: Inconsistent boom or bucket movement, with noticeable jerking or delays.
  
• Cause: Faulty or worn-out hydraulic valves, sticking valve spools, or damaged seals.
  
• Solution: Inspect the hydraulic valves for wear or sticking. If necessary, replace or repair the faulty valves. Regular inspection and cleaning of valves can prevent these issues.
  

6. Pressure Relief Valve Issues
The pressure relief valve is designed to maintain a safe operating pressure within the hydraulic system by diverting fluid when the pressure exceeds a certain level. If this valve becomes stuck or malfunctions, it may not properly regulate the pressure, causing surges or drops in hydraulic pressure.

• Symptoms: Sudden pressure surges or jerking movements, particularly when the machine is under load.
  
• Cause: Faulty or improperly set pressure relief valve.
  
• Solution: Test the pressure relief valve to ensure it is set correctly. If malfunctioning, repair or replace the valve.
  

Preventing Hydraulic Pulsation in the Future
Preventing hydraulic pulsation involves routine maintenance, attention to detail, and prompt repairs when issues arise. Here are a few tips to minimize the chances of hydraulic pulsation in the future:

1. Regularly Check Hydraulic Fluid: Ensure that the hydraulic fluid is at the correct level and that it’s free of contaminants. Changing the fluid and filters on a scheduled basis will prolong the life of the system and prevent contamination from causing issues.
   
2. Inspect Hoses and Seals: Hoses, seals, and fittings should be inspected for leaks regularly. Air entering the system is often the result of damaged seals, which can be easily replaced with minimal downtime.
   
3. Maintain the Hydraulic Pump: The hydraulic pump should be checked regularly for signs of wear or damage. Keeping the pump in good condition is crucial for maintaining consistent hydraulic performance.
   
4. Clean or Replace Filters: Hydraulic filters should be inspected and cleaned, or replaced as needed, to ensure they don’t restrict fluid flow.
   
5. Properly Calibrate the Pressure Relief Valve: Ensure the pressure relief valve is calibrated correctly to prevent excessive pressure from building up in the system.
   
6. Train Operators: Educate machine operators on the signs of hydraulic issues, including pulsation. Early detection can prevent more severe problems from developing.
   

Conclusion
Hydraulic pulsation in excavators, such as the Komatsu PC160-7, can significantly impact the performance and efficiency of the machine. By understanding the common causes of hydraulic pulsation, such as air in the system, low or contaminated fluid, faulty pumps, clogged filters, valve malfunctions, and pressure relief valve issues, operators can identify and resolve the problem more effectively.
Routine maintenance, such as checking fluid levels, replacing filters, and inspecting the pump and valves, will help prevent pulsation issues from arising in the future. By staying proactive and addressing hydraulic issues promptly, operators can ensure their machines run smoothly, improving productivity and minimizing the risk of costly repairs.