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MODEL: HITACHI, KOMATSU, SUMITOMO, KOBELCO, VOLVO, DOOSAN, CATERPILLAR, HYUNDAI ISUZU: 4BD1T, 4BG1T, 6BD1T, 6RB1T, 6SD1T, 6BG1T, 6WG1T,6HK1T, 4HK1T, 4JJ1T HINO: H06CT, EP100T, J05E, J08E MITSUBISHI:: 6D22T, 6D31T, 6D15T, 4D31T, 6D14T,6D22T KOMATSU: S6D95, S6D108 CUMMIN: 6BT, 6CT, S6D102, S6D105, S6D107E, S6D114, S6D125 DOOSAN: D1146, D2366, DB58 VOLVO: D8K, D4D, D4E, D12D, D5E, D6E >>Whatsapp us 011-11623216 to confirm the model and size. FREE catalogue on our website:

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The center joint, also known as the rotary joint or swivel joint, is a crucial component in an excavator that allows hydraulic fluid to flow between the stationary and rotating parts of the machine. The center joint cover protects this component from external damage and contaminants. If the center joint cover fails to function properly or is damaged, it can lead to several issues affecting the performance, safety, and longevity of the excavator. Here are the common problems associated with a non-functional center joint cover:

1. Contamination Issues

  1. Dirt and Debris Ingress:
  • Hydraulic System Contamination: A damaged or non-functional cover can allow dirt, dust, and debris to enter the center joint, leading to contamination of the hydraulic fluid. This can cause wear and damage to the hydraulic system components.
  • Increased Wear: Contaminants can cause increased friction and wear on the seals and internal components of the center joint, leading to premature failure.

2. Component Damage

  1. Exposure to Elements:
  • Corrosion: Exposure to water, moisture, and other environmental elements can cause corrosion of the center joint and its components, reducing their lifespan and effectiveness.
  • Physical Damage: Without the protective cover, the center joint is more susceptible to physical damage from rocks, debris, and other impacts during operation.

3. Hydraulic System Issues

  1. Leakage:
  • Seal Damage: Contaminants and physical damage can compromise the seals within the center joint, leading to hydraulic fluid leaks. This can reduce the efficiency of the hydraulic system and lead to a loss of hydraulic power.
  • Pressure Loss: Leaks can cause a drop in hydraulic pressure, affecting the performance of hydraulic functions such as lifting, digging, and swinging.

4. Operational Downtime

  1. Frequent Repairs:
  • Maintenance Interruptions: A damaged center joint cover can lead to frequent repairs and maintenance checks to address contamination and leaks, resulting in operational downtime and decreased productivity.
  • Unexpected Breakdowns: Failure to protect the center joint can result in unexpected breakdowns, causing significant delays in operations and increased repair costs.

5. Safety Concerns

  1. Machine Instability:
  • Compromised Performance: Issues with the hydraulic system due to a non-functional center joint cover can compromise the stability and control of the excavator, posing safety risks to the operator and nearby workers.
  • Accidents: Hydraulic system failures can lead to accidents, such as loss of control over the boom or bucket, increasing the risk of injury and equipment damage.

6. Increased Operating Costs

  1. Higher Maintenance Costs:
  • Component Replacement: Increased wear and damage to the center joint and related components can lead to higher maintenance and replacement costs over time.
  • Fluid Replacement: Contamination of the hydraulic fluid may require more frequent fluid changes and filtration, adding to operating costs.


A non-functional center joint cover can lead to contamination issues, component damage, hydraulic system problems, operational downtime, safety concerns, and increased operating costs. Ensuring that the center joint cover is in good condition and properly maintained is crucial for protecting the hydraulic system, maintaining the performance and safety of the excavator, and reducing maintenance costs. Regular inspection and timely replacement of the center joint cover can help prevent these problems and ensure smooth and efficient operation 


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