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Komatsu PC200-6 Pump Rebuild: Swash Plate, Cam, and Rocker Issues
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The Komatsu PC200-6 is a highly reliable hydraulic excavator that has been widely used in various construction, mining, and excavation applications. One of the critical components of this machine is its hydraulic pump, which drives the excavator’s boom, arm, bucket, and other essential functions. Over time, the pump can experience issues, including wear and tear of specific parts like the swash plate, cam, and rocker. These parts play a crucial role in the hydraulic system's efficiency and performance.
In this article, we will explore the common issues faced during the Komatsu PC200-6 pump rebuild process, focusing on the swash plate, cam, and rocker, their functions, and how to address problems associated with them.
Understanding the Hydraulic Pump System
The hydraulic pump in the Komatsu PC200-6 is responsible for providing the pressure needed to operate the hydraulic cylinders and motors, enabling the machine to perform its work. The system consists of several key components, including the swash plate, cam, and rocker. Each of these components plays a specific role in the movement and control of hydraulic fluid, which powers the excavator’s various functions.
  • Swash Plate: The swash plate is a critical component that helps convert the rotational motion of the pump’s motor into hydraulic pressure. It tilts at a specific angle to determine the amount of displacement (flow) in the pump.
  • Cam: The cam is responsible for guiding the movement of the pistons within the hydraulic pump. The cam follows the rotation of the swash plate, allowing it to control the flow of fluid.
  • Rocker: The rocker arm is a mechanical link between the cam and the pistons. It transfers the cam’s motion to the pistons, pushing the hydraulic fluid through the pump and into the system.
Together, these components ensure that the hydraulic system operates efficiently, providing the power needed to lift, dig, and move materials on the job site.
Common Problems with the Swash Plate, Cam, and Rocker
While the Komatsu PC200-6’s hydraulic pump is built to last, there are a few common issues that operators and maintenance technicians may encounter over time. These issues are often related to wear, improper maintenance, or fluid contamination. Below are the most common problems that arise with the swash plate, cam, and rocker.
1. Swash Plate Wear
Over time, the swash plate can experience wear due to friction and pressure from the hydraulic fluid. This wear can cause the plate to lose its precision, which affects the pump’s ability to maintain consistent hydraulic pressure. Symptoms of swash plate wear may include:
  • Erratic operation: Inconsistent power delivery to the hydraulic system, causing the machine to operate unevenly.
  • Reduced efficiency: The pump may fail to generate the required pressure for smooth operation, leading to reduced performance of the excavator.
  • Overheating: Increased friction due to wear can lead to overheating of the hydraulic system.
To address swash plate wear, it’s crucial to regularly inspect the plate and ensure that it’s properly lubricated. In severe cases, replacing the swash plate may be necessary.
2. Cam and Rocker Issues
The cam and rocker are responsible for controlling the movement of the hydraulic pistons. If either of these components becomes damaged or worn, the entire hydraulic system can be affected. Some common issues include:
  • Cam damage: The cam can suffer from wear and pitting, particularly if the hydraulic fluid has become contaminated or the pump is improperly maintained. This can result in irregular piston movement and fluctuating hydraulic pressure.
  • Rocker wear: Similar to the cam, the rocker arm can experience wear due to constant movement. This can cause misalignment and improper piston operation, resulting in inconsistent hydraulic flow.
Symptoms of cam and rocker issues may include:
  • Poor hydraulic performance: The excavator may struggle to lift heavy loads or perform tasks that require high hydraulic power.
  • Unusual noises: Grinding or whining noises may be heard as the cam and rocker components experience excessive friction or misalignment.
  • Sluggish or jerky movements: The bucket, boom, or arm may move slowly or jerk when operated.
3. Hydraulic Fluid Contamination
Contaminated hydraulic fluid is a significant cause of wear and damage to the pump components, including the swash plate, cam, and rocker. Contaminants such as dirt, water, or metal particles can enter the hydraulic system and cause excessive friction, accelerating the wear of these parts.
Signs of contaminated fluid include:
  • Discolored fluid: Hydraulic fluid that appears milky or has a dark color may indicate water contamination or overheating.
  • Filtration issues: A clogged filter or an increase in filter replacement frequency could suggest that the hydraulic fluid is carrying contaminants.
  • Erratic hydraulic behavior: Contaminants in the fluid can cause the pump to malfunction, leading to irregular or inefficient hydraulic operation.
Steps for Rebuilding the Hydraulic Pump
When rebuilding the hydraulic pump on a Komatsu PC200-6, it is crucial to address any issues with the swash plate, cam, rocker, and other internal components. Below is a general step-by-step guide to performing a pump rebuild:
1. Disassemble the Hydraulic Pump
Begin by removing the hydraulic pump from the excavator. This may require disconnecting hydraulic lines and other components. Once removed, carefully disassemble the pump to access the swash plate, cam, and rocker.
2. Inspect the Swash Plate, Cam, and Rocker
Inspect the swash plate, cam, and rocker for signs of wear or damage. Look for any unusual wear patterns, pitting, or cracks. Use a micrometer to measure the swash plate’s thickness and ensure it meets the manufacturer’s specifications. Similarly, check the cam and rocker for any signs of excessive wear or misalignment.
3. Clean and Replace Components
Thoroughly clean all components and remove any dirt, debris, or old hydraulic fluid. If the swash plate, cam, or rocker is worn beyond repair, replace the damaged components with new ones. It’s essential to use OEM (Original Equipment Manufacturer) parts to ensure compatibility and maintain performance.
4. Lubricate Moving Parts
Lubricate the moving parts, such as the cam and rocker, with the appropriate hydraulic oil. Proper lubrication helps reduce friction and ensures smooth movement during operation.
5. Reassemble and Test
Reassemble the pump and reinstall it on the excavator. Once installed, test the hydraulic system to ensure that it operates smoothly and efficiently. Monitor the system for any unusual sounds, leaks, or performance issues.
Preventing Future Hydraulic Pump Issues
To prolong the life of the hydraulic pump and prevent issues with the swash plate, cam, and rocker, it’s essential to follow proper maintenance practices:
  • Regular fluid changes: Replace hydraulic fluid at the recommended intervals to prevent contamination and ensure optimal performance.
  • Monitor filter condition: Regularly check and replace hydraulic filters to prevent contaminants from entering the system.
  • Perform regular inspections: Regularly inspect the hydraulic pump and components for signs of wear or damage. Address issues early to prevent costly repairs.
Conclusion
The hydraulic pump of the Komatsu PC200-6 is a critical component of the machine's overall performance. Understanding the common issues with the swash plate, cam, and rocker, and knowing how to address them during a rebuild, can significantly extend the life of the hydraulic system and maintain the excavator’s productivity. Regular maintenance, proper fluid care, and timely component replacement are key to keeping the hydraulic system in peak condition.
By following the steps outlined in this guide and addressing issues as they arise, operators and technicians can ensure the long-term reliability and performance of the Komatsu PC200-6.
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Komatsu PC200-6 Pump Rebuild: Swash Plate, Cam, and Rocker Issues - by MikePhua - Yesterday, 06:40 PM

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