Understanding and Addressing Swing Play in Hitachi EX120-2 Excavators

[MikePhua]

Swing play in excavators refers to the unwanted movement or "play" in the swing mechanism, which can affect the machine's performance and precision. In the case of the Hitachi EX120-2, this issue has been observed and documented by operators, highlighting the importance of understanding its causes and solutions.
Causes of Swing Play

1. Worn Swing Bearings: Over time, the swing bearings can wear out due to constant movement and load-bearing. This wear leads to increased clearance between the bearing components, resulting in noticeable play during operation.
   
2. Hydraulic System Issues: The swing motor and its associated hydraulic components are crucial for smooth rotation. Any issues such as low hydraulic fluid levels, air in the system, or malfunctioning valves can cause inconsistent pressure, leading to swing play.
   
3. Improper Lubrication: Inadequate or improper lubrication of the swing mechanism can accelerate wear and cause uneven movement, contributing to swing play.
   
4. Structural Misalignments: If the swing frame or related structures are misaligned due to impacts or manufacturing defects, it can cause uneven loading on the swing bearings, leading to play.
   

Symptoms of Swing Play

• Excessive movement or "play" when the swing function is engaged.
  
• Slower response times when initiating swing movements.
  
• Unusual noises such as grinding or clicking during rotation.
  
• Inconsistent or jerky movement when changing swing directions.
  

Diagnostic Steps

1. Visual Inspection: Check for any visible signs of wear or damage on the swing bearings and associated components.
   
2. Hydraulic Pressure Check: Use a pressure gauge to monitor the hydraulic pressure during swing operations. Fluctuations or drops in pressure can indicate issues within the hydraulic system.
   
3. Lubrication Assessment: Ensure that the swing mechanism is properly lubricated and that the lubrication system is functioning correctly.
   
4. Alignment Verification: Inspect the swing frame and related structures for any signs of misalignment or deformation.
   

Repair and Maintenance Solutions

• Swing Bearing Replacement: If wear is identified, replacing the swing bearings can restore proper function.
  
• Hydraulic System Overhaul: Addressing issues such as replacing worn seals, cleaning filters, and ensuring proper fluid levels can resolve hydraulic-related causes of swing play.
  
• Lubrication System Maintenance: Regularly servicing the lubrication system and using the correct type of lubricant can prevent lubrication-related issues.
  
• Structural Realignment: If misalignment is detected, realigning the swing frame and related components can eliminate play.
  

Preventive Measures

• Regular Inspections: Conduct routine checks of the swing mechanism, hydraulic system, and lubrication system to identify potential issues early.
  
• Proper Operation: Avoid overloading the machine and operate within recommended parameters to reduce stress on the swing mechanism.
  
• Scheduled Maintenance: Adhere to the manufacturer's maintenance schedule for the EX120-2 to ensure all components are functioning optimally.
  

Conclusion
Addressing swing play in the Hitachi EX120-2 excavator involves understanding its causes, symptoms, and implementing appropriate diagnostic and repair procedures. By maintaining the swing mechanism and associated systems, operators can ensure the longevity and efficiency of their equipment.