Komatsu D31P-20 Bevel Gear Adjustment and Torque Specifications

[MikePhua]

Introduction
The Komatsu D31P-20 is a versatile crawler dozer designed for various construction and mining applications. One of its critical components is the bevel gear assembly, which plays a vital role in transmitting power from the engine to the final drive, enabling the machine's movement. Proper adjustment and maintenance of the bevel gear are essential for optimal performance and longevity of the dozer.
Bevel Gear Assembly Overview
The bevel gear assembly in the D31P-20 consists of several key components:

• Bevel Pinion: This gear meshes with the bevel gear to transmit rotational force.
  
• Bevel Gear: Receives power from the bevel pinion and transfers it to the final drive.
  
• Bevel Gear Shaft: Supports the bevel gear and transmits torque.
  
• Cage: Houses the bevel gear and pinion, ensuring proper alignment.
  
• Lock Plate: Secures the assembly components in place.
  

Adjustment Procedures

1. Backlash Measurement: Backlash refers to the slight movement between meshing gears. For the D31P-20, the recommended backlash is between 0.18 to 0.23 mm. To measure this, insert a fuse wire between the gears, rotate them, and then measure the crushed wire's thickness using a micrometer.
   
2. Rotating Torque: The rotating torque of the bevel gear shaft should be between 1.4 to 2.4 Nm (0.14 to 0.24 kgm). This ensures that the gears mesh smoothly without excessive resistance.
   
3. Adjustment Nut Tightening: After achieving the correct backlash and rotating torque, tighten the adjustment nut to a torque of 392.3 to 490.3 Nm (45 to 50 kgm). This secures the bevel gear in its optimal position.
   
4. Tooth Contact Pattern: Coat the tooth faces of the bevel gears with a thin layer of red lead. Rotate the gears and inspect the contact pattern. The ideal pattern should cover about 30% of the tooth length, starting near the small end and centered on the tooth height.
   
5. Shim Adjustment: If the tooth contact pattern is not correct, adjust the shim thickness at the mounting face of the bevel pinion assembly cage and steering case. This will move the pinion shaft closer or further from the bevel gear, altering the contact pattern.
   

Torque Specifications

• Bevel Gear Shaft Rotating Torque: 1.4 to 2.4 Nm (0.14 to 0.24 kgm)
  
• Adjustment Nut Tightening Torque: 392.3 to 490.3 Nm (45 to 50 kgm)
  

Maintenance Tips

• Regularly check the backlash and rotating torque to ensure proper gear meshing.
  
• Inspect the tooth contact pattern periodically to detect any misalignments.
  
• Replace any worn or damaged components promptly to prevent further damage.
  
• Always use the specified torque values when tightening components to avoid over-tightening or under-tightening.
  

Conclusion
Proper adjustment and maintenance of the bevel gear assembly in the Komatsu D31P-20 are crucial for the machine's performance and longevity. By following the recommended procedures and specifications, operators can ensure smooth operation and minimize downtime. Regular inspections and timely maintenance will contribute to the dozer's reliability and efficiency on the job site.