Relief Valve for Main pump, swing motor, travel motor



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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If the relief valve for the main pump, swing motor, or travel motor malfunctions or fails to function properly, it can lead to various critical issues affecting the hydraulic system, performance, and safety of the excavator or other heavy machinery. Here are some common problems associated with a faulty relief valve:

1. Main Pump Relief Valve:

Hydraulic System Overpressure:

  • Damage to Components: A malfunctioning relief valve may allow excessive pressure to build up in the hydraulic system, potentially causing damage to components such as hoses, seals, cylinders, and the main pump itself.
  • System Overload: High pressure can overload the hydraulic system, leading to increased wear and potential failure of components over time.

Loss of Control:

  • Uncontrolled Movements: Excessive pressure can cause uncontrolled movements of the machine's hydraulic actuators, leading to safety hazards and loss of control over the equipment.
  • Erratic Operation: The excavator may experience erratic operation, with sudden movements or jerks, posing a risk to the operator and nearby workers.

Hydraulic Fluid Leakage:

  • Seal Damage: Overpressure can damage hydraulic seals, resulting in leaks and fluid loss from the system.
  • Environmental Impact: Hydraulic fluid leaks can contaminate the environment and pose a risk of soil or water pollution.

2. Swing Motor Relief Valve:

Swing System Malfunction:

  • Loss of Swing Control: A malfunctioning relief valve may cause erratic or uncontrolled swinging movements of the excavator's upper structure, affecting the operator's ability to maneuver the machine safely.
  • Swing Motor Damage: Overpressure can damage the swing motor, leading to decreased performance, increased wear, and potential failure.

Safety Concerns:

  • Risk of Accidents: Uncontrolled swinging movements can pose a significant safety risk to the operator, nearby workers, and equipment in the vicinity of the excavator.
  • Equipment Damage: Improper swing control may result in collisions with obstacles or other machinery, causing damage to equipment and property.

3. Travel Motor Relief Valve:

Drive System Issues:

  • Loss of Traction: Malfunctioning relief valves can lead to loss of traction or uneven drive performance, affecting the excavator's ability to move efficiently on various terrain types.
  • Drive System Damage: Overpressure can damage the travel motor or related components, leading to reduced reliability, increased maintenance costs, and potential downtime.

Safety Risks:

  • Unintended Movement: Hydraulic pressure spikes or uncontrolled flow can result in unintended movement of the excavator, posing a risk of accidents or collisions on the job site.
  • Loss of Stability: Improper relief valve function may compromise the stability and balance of the excavator, increasing the risk of tip-overs or rollovers, especially on uneven ground.


A malfunctioning or non-functional relief valve for the main pump, swing motor, or travel motor can lead to hydraulic system overpressure, loss of control, hydraulic fluid leakage, swing system malfunction, safety concerns, drive system issues, and increased risk of accidents or equipment damage. Prompt inspection, diagnosis, and replacement of faulty relief valves by a qualified technician are crucial to maintain optimal hydraulic system performance, safety, and reliability of the excavator or heavy machinery. Regular maintenance and inspection of relief valves can help prevent these issues and ensure safe operation on the job site. 


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