Aftermarket Slewing Ring Bearings for Hitachi EX60-5 Excavators

[MikePhua]

The Hitachi EX60-5 and Its Swing System Architecture
The Hitachi EX60-5 hydraulic excavator was part of Hitachi’s fifth-generation compact excavator series, introduced in the late 1990s. With an operating weight of approximately 6 metric tons and powered by the Isuzu 4JB1 engine, the EX60-5 was designed for urban excavation, utility trenching, and light demolition. One of its critical components is the slewing ring bearing—also known as the swing bearing or rotec bearing—which supports the upper structure and enables 360-degree rotation.
Terminology annotation:

• Slewing Ring Bearing: A large-diameter bearing that allows rotational movement between the upper and lower structures of an excavator.
  
• Rotec Bearing: A brand name often used generically to refer to slewing rings, originally developed for cranes and heavy machinery.
  
• Swing Gear: The toothed ring that interfaces with the swing motor pinion to rotate the upper frame.
  
• Preload: The axial force applied during bearing installation to eliminate play and ensure proper load distribution.
  

In British Columbia, a contractor operating an EX60-5 noticed excessive play and grinding noise during rotation. Upon inspection, the slewing ring showed signs of pitting and seal failure. Faced with a steep OEM replacement cost, he explored aftermarket options.
OEM vs Aftermarket Slewing Ring Bearings
Original Hitachi slewing rings are precision-engineered and tested for long-term durability. However, their cost can be prohibitive—often five times higher than aftermarket alternatives. For machines nearing the end of their service life or operating in low-hour seasonal roles, aftermarket bearings offer a viable solution.
Comparison factors:

• OEM bearings typically last 10,000–15,000 hours under normal conditions
  
• Aftermarket bearings may offer 4,000–8,000 hours depending on metallurgy and seal quality
  
• OEM units include factory preload specifications and matched gear profiles
  
• Aftermarket units may require manual tolerance checks and gear backlash adjustment
  

Recommendations:

• Source aftermarket bearings from reputable suppliers with ISO-certified manufacturing
  
• Confirm gear pitch and bolt pattern compatibility before purchase
  
• Inspect bearing raceway hardness—target Rockwell HRC 55–60
  
• Verify seal type—double-lip nitrile or polyurethane preferred for dust and water resistance
  
• Request dimensional drawings and installation torque specs
  

In Germany, an equipment dealer installed an aftermarket slewing ring in a Komatsu PC300. Twelve years later, the machine was still operating locally, suggesting that quality aftermarket options can deliver long-term value when properly installed.
Installation Considerations and Tolerance Verification
Replacing a slewing ring bearing requires precision and patience. The bearing must be seated evenly, torqued to spec, and checked for axial and radial play. Improper installation can lead to premature wear, gear misalignment, or seal extrusion.
Installation steps:

• Remove upper structure using crane or gantry system
  
• Clean bearing seat and inspect for pitting or warping
  
• Apply anti-seize compound to mating surfaces
  
• Align bolt holes and torque in star pattern to manufacturer spec
  
• Measure axial play—target 0.1–0.3 mm depending on bearing size
  
• Check gear backlash between swing pinion and internal gear
  

Recommendations:

• Use dial indicator to measure bearing runout after installation
  
• Replace mounting bolts with grade 10.9 or higher
  
• Recheck torque after 10 hours of operation
  
• Grease bearing with lithium-based EP grease every 100 hours
  
• Monitor swing noise and vibration during initial operation
  

In Alberta, a technician installed a slewing ring in an EX60-5 during winter downtime. By carefully measuring preload and gear engagement, he achieved smooth rotation and eliminated the previous grinding issue.
Seal Integrity and Lubrication Strategy
Seal failure is one of the most common causes of slewing ring degradation. Once contaminants enter the raceway, bearing life drops sharply. Aftermarket bearings may use lower-grade seals, so proactive maintenance becomes essential.
Seal care tips:

• Inspect seal lip for cracks or extrusion during installation
  
• Use high-viscosity grease to maintain seal pressure
  
• Avoid pressure washing near bearing housing
  
• Monitor grease purge from seal area—excess may indicate overpacking
  
• Replace seal if leakage or contamination is detected
  

Lubrication guidelines:

• Use lithium complex grease with molybdenum disulfide additive
  
• Apply grease via central fitting or multiple ports depending on bearing design
  
• Grease every 100 hours or weekly in high-duty cycles
  
• Rotate upper structure during greasing to distribute lubricant evenly
  
• Purge old grease annually and inspect for metal particles
  

In Texas, a demolition crew added a remote greasing line to their EX60-5’s slewing ring. This allowed daily maintenance without climbing the machine, improving uptime and reducing bearing wear.
Cost-Benefit Analysis and Long-Term Planning
Choosing between OEM and aftermarket slewing rings depends on machine usage, budget, and downtime tolerance. For high-hour machines nearing retirement, aftermarket bearings can extend service life at a fraction of the cost. For primary production units, OEM may be justified by longer lifespan and warranty support.
Decision matrix:

• Low-hour seasonal machine → Aftermarket bearing with verified specs
  
• High-production excavator → OEM bearing with full warranty
  
• Tight budget and skilled labor → Aftermarket with tolerance checks
  
• Remote location with limited support → OEM for reliability
  

Recommendations:

• Document bearing source, specs, and installation torque
  
• Keep spare seals and grease fittings in field inventory
  
• Monitor swing performance monthly and log anomalies
  
• Schedule bearing inspection every 1,000 hours or annually
  

In Ontario, a fleet manager standardized aftermarket bearings across his older excavators. With consistent installation procedures and proactive greasing, he reduced swing failures by 70% over three years.
Conclusion
Aftermarket slewing ring bearings for the Hitachi EX60-5 offer a practical alternative to OEM replacements when sourced and installed correctly. While metallurgy, seal quality, and gear profile must be verified, the cost savings and field performance can be substantial. In the world of compact excavators, rotation is more than motion—it’s precision under pressure. And every bearing tells a story of torque, tolerance, and trust.