Proper Turntable Greasing for Excavators Like the Hitachi EX270

[MikePhua]

Why Turntable Greasing Is Critical
The turntable, also known as the slewing ring or Rotec bearing, is one of the most vital components in an excavator’s upper structure. It allows the house to rotate 360 degrees while supporting the weight of the cab, boom, and counterweight. Without proper lubrication, this bearing can seize, wear prematurely, or even fail catastrophically. Greasing the turntable is not just a maintenance task—it’s a safeguard against downtime and costly repairs.
Understanding the Grease Points and Access Locations
On machines like the Hitachi EX270, there are typically two types of greasing operations related to the turntable:

• Bearing race lubrication: This involves injecting grease into the bearing race via grease zerks (fittings). These are usually located at the front and rear of the swing bearing, and sometimes on both sides.
  
• Swing gear lubrication: The swing gear, located beneath the cab and inside the carbody tub, requires a separate greasing method. This gear is not pressure-lubricated and relies on packed grease to prevent wear and corrosion.
  

In many models, an oval access plate—often found in the battery box or toolbox area—provides entry to the swing gear cavity. This plate is large enough for a hand to pass through and is typically secured with bolts.
Recommended Grease Types and Application Frequency
For the bearing race, use a high-pressure molybdenum disulfide (moly) grease, typically rated EP2 or higher. This type of grease resists extreme pressure and adheres well to metal surfaces. For the swing gear cavity, a tacky, water-resistant grease with anti-wear additives is preferred.
Suggested greasing intervals:

• Turntable bearing zerks: Weekly or every 50 hours of operation. Apply 5–10 pumps per fitting. Rotate the house a few times between pumps to distribute grease evenly.
  
• Swing gear cavity: Every 6–12 months, depending on usage and environmental conditions. Remove old grease and replenish with 2–3 tubes of fresh grease.
  

Avoid over-greasing the bearing race, as excessive pressure can dislodge the internal seals, allowing contaminants to enter and grease to escape.
Step-by-Step Swing Gear Greasing

1. Locate the access plate near the swing motor or inside the toolbox compartment.
   
2. Remove the plate and scoop out old grease and debris.
   
3. Inspect for water accumulation—this cavity is not sealed and often collects moisture. Drain if necessary.
   
4. Apply fresh grease by hand or with a spatula, ensuring coverage of the gear teeth.
   
5. Have a trusted operator slowly rotate the house while you apply grease. Keep your hand clear of the gear path at all times.
   
6. Reinstall the access plate securely.
   

Additional Maintenance Tips

• Drain the swing gear tub annually: A bottom plate under the carbody allows water and degraded grease to be removed. Tilt the machine slightly to aid drainage.
  
• Use consistent grease types: Mixing incompatible greases can cause separation or chemical breakdown. If unsure of the previous grease, clean out the cavity before switching.
  
• Monitor for noise or vibration: Grinding or popping sounds during swing operations may indicate insufficient lubrication or bearing wear.
  

Conclusion
Greasing the turntable on an excavator like the Hitachi EX270 is a multi-step process that requires attention to detail and safety. By understanding the difference between bearing and gear lubrication, using the right grease, and maintaining a regular schedule, operators can extend the life of their swing system and avoid costly failures. A few minutes of maintenance can prevent thousands in repairs and keep the machine rotating smoothly through every cycle.