1977 Link-Belt LS108 Excavator Overview

[MikePhua]

Machine Background
The Link-Belt LS108 was a mid-sized excavator introduced in the 1970s by Link-Belt Construction Equipment Company, a pioneering manufacturer in hydraulic excavators and crawler systems. The LS108 combined a reliable 6-cylinder diesel engine, producing around 95–110 horsepower, with a robust hydraulic system capable of lifting and digging under demanding conditions. Link-Belt was historically known for innovations in hydraulic swing and boom control, which allowed smoother operation compared to earlier cable-operated models. The LS108 was part of a lineup aimed at general construction, road work, and quarry applications, and it sold in moderate numbers due to its reputation for durability.

Common Issues
Operators have reported typical wear and maintenance challenges associated with vintage hydraulic excavators like the LS108:

• Hydraulic leaks from boom, stick, and swing cylinders, often caused by worn seals or o-rings.
  
• Engine starting difficulties, particularly in cold weather or after long idle periods.
  
• Swing gear and pin wear, leading to uneven movement or noise during operation.
  
• Track wear and tension problems, which could cause uneven track wear or reduced stability on slopes.
  
• Control valve sluggishness, often due to contaminated hydraulic fluid or internal wear.
  

Technical Definitions

• Boom Cylinder: Hydraulic cylinder controlling the vertical movement of the boom.
  
• Stick Cylinder: Controls the movement of the dipper or arm attached to the boom.
  
• Hydraulic Reservoir: Tank storing fluid for the hydraulic system, equipped with a filter to prevent contamination.
  
• Swing Gear: Mechanical gear enabling the upper structure to rotate independently from the undercarriage.
  
• O-ring: Circular seal used to prevent fluid leakage in hydraulic and engine systems.
  

Maintenance Recommendations

• Hydraulic System
  • Regularly inspect cylinder rods for nicks or pitting and replace worn seals.
    
  • Monitor hydraulic fluid levels and change fluid every 500–1000 operating hours depending on work conditions.
    
  • Clean or replace hydraulic filters to prevent valve blockages and sluggish control response.
    
• Engine
  • Use diesel with appropriate cetane rating for cold starts.
    
  • Inspect fuel lines and injectors to avoid air locking and ensure consistent fuel delivery.
    
  • Perform oil and coolant changes at regular intervals; typical engine oil capacity is about 22 liters (5.8 gallons).
    
• Undercarriage
  • Maintain track tension according to manufacturer specifications to prevent accelerated wear.
    
  • Inspect sprockets and rollers for uneven wear; replace in matched sets when possible.
    
• Swing System
  • Lubricate swing gear periodically and monitor for excessive backlash.
    
  • Replace worn pins and bushings before they cause structural damage.
    

Operational Tips

• Warm up the hydraulic system for several minutes in cold conditions before heavy digging to reduce shock on seals.
  
• Avoid continuous maximum-load digging; cycle the boom and stick to prolong cylinder life.
  
• Keep the machine clean, especially the radiator and hydraulic cooler, to prevent overheating.
  
• When operating on slopes, extend the undercarriage and keep the boom low to maintain stability.
  

Real-World Example
A contractor in rural Ohio purchased a 1977 LS108 with over 10,000 operating hours. After replacing worn hydraulic seals and servicing the swing system, the excavator continued to operate reliably on trenching jobs for municipal water lines. The machine’s hydraulic flow rate of 75 L/min (19.8 gpm) allowed precise control for delicate excavation near utilities, demonstrating why the LS108 remained valued despite its age.

Parts & Service References

• Hydraulic Seal Kits: Essential for boom, stick, and swing cylinders; often sold as individual cylinder kits for the LS108.
  
• Track Components: Includes sprockets, rollers, and idlers compatible with the LS108 undercarriage.
  
• Engine Parts: Filters, injectors, and belts for the 6-cylinder diesel engine.
  

Conclusion
The 1977 Link-Belt LS108 is a durable excavator that remains functional decades after production due to its solid design and hydraulic innovations. Routine inspection of the hydraulic system, proper engine maintenance, and attention to undercarriage and swing components can extend the machine’s life and ensure reliable operation in construction, farming, and quarry applications. Regular preventive measures like fluid replacement, seal inspections, and track adjustments are critical to preserving performance on this classic excavator.