Komatsu D58 Steering System Diagnosis and Field Solutions

[MikePhua]

The Evolution of the Komatsu D58 Series
Komatsu, founded in 1921 in Japan, has long been a global leader in earthmoving equipment. The D58 crawler dozer was introduced in the late 1970s as a mid-size machine designed for grading, land clearing, and light-to-medium construction work. Positioned between the smaller D31 and the heavier D65, the D58 offered a balance of power and maneuverability, making it popular in forestry, road building, and agricultural applications.
The D58 featured a direct-drive transmission, mechanical steering clutches, and a torque converter system. Its robust undercarriage and simple mechanical layout made it a favorite among operators who valued reliability over complexity. Thousands of units were sold across Asia, North America, and Africa, with many still in service today due to their rebuildable components and straightforward design.
Understanding the Steering System Architecture
The Komatsu D58 uses a dual steering clutch and brake system to control track movement. Each track is independently operated via a lever that engages a clutch pack and brake band. Steering is achieved by disengaging the clutch on one side and applying the brake, causing the machine to pivot.
Terminology notes:

• Steering clutch: A multi-disc assembly that disconnects power from the final drive to the track.
  
• Brake band: A friction surface that slows or stops the track when applied.
  
• Final drive: The gear assembly that transmits torque from the transmission to the track sprockets.
  
• Torque converter: A fluid coupling that multiplies engine torque and allows smooth gear transitions.
  

The system is mechanical, relying on springs, linkages, and hydraulic assist (in some variants) to operate. Unlike hydrostatic machines, the D58’s steering requires deliberate input and regular adjustment.
Common Steering Problems and Their Root Causes
Operators of aging D58 units often report steering issues such as:

• Loss of steering on one side: Typically caused by worn clutch discs or broken return springs.
  
• Delayed engagement: May result from contaminated clutch packs or misadjusted linkages.
  
• Hard steering levers: Often due to seized pivot points or dried-out bushings.
  
• Brake fade: Caused by oil contamination or worn brake linings.
  

A technician in Queensland shared a case where a D58 failed to steer left. After disassembling the clutch housing, he found the friction discs glazed and the pressure plate warped. Replacing the clutch pack and adjusting the linkage restored full steering function.
Another issue arises when steering works only at high RPM. This suggests insufficient clutch pressure or weak springs. In some cases, oil contamination from leaking seals causes the clutch discs to slip, requiring a full teardown and reseal.
Diagnostic Steps and Inspection Strategy
To diagnose steering problems on a Komatsu D58:

• Check lever travel: Ensure both steering levers have equal movement and return smoothly.
  
• Inspect clutch housing: Remove inspection covers and check for oil contamination or broken springs.
  
• Test brake engagement: With the machine stationary, apply each brake and observe track resistance.
  
• Verify linkage alignment: Misaligned rods or worn bushings can prevent full clutch engagement.
  
• Monitor fluid levels: Low transmission or hydraulic fluid can affect clutch assist systems.
  

Recommended tools include:

• Torque wrench for clutch spring preload
  
• Dial indicator for measuring plate warpage
  
• Brake lining gauge
  
• Inspection mirror and flashlight for housing checks
  

Repair Procedures and Component Replacement
When steering components fail, repairs may involve:

• Removing the clutch housing cover
  
• Extracting and replacing clutch discs and pressure plates
  
• Installing new return springs and adjusting preload
  
• Replacing brake bands and linings
  
• Cleaning and resealing the housing to prevent future contamination
  

Use OEM-grade parts or high-quality aftermarket kits with matched friction materials. Always soak new clutch discs in transmission fluid before installation to prevent dry engagement.
For brake band replacement:

• Remove the brake drum cover
  
• Inspect the drum surface for scoring
  
• Install new linings and adjust clearance using the manufacturer’s spec
  
• Test brake engagement under load
  

Preventive Maintenance and Long-Term Reliability
To extend the life of the D58’s steering system:

• Grease all pivot points monthly
  
• Inspect clutch and brake housings every 500 hours
  
• Replace transmission fluid annually
  
• Adjust steering linkages quarterly
  
• Monitor for signs of oil leaks around final drives and clutch housings
  

Some owners retrofit grease fittings to inaccessible bushings and install inspection ports for easier clutch checks. These modifications improve serviceability without altering core functionality.
In 2023, a forestry crew in British Columbia rebuilt the steering system on a 1981 D58P. After replacing both clutch packs, brake bands, and linkage bushings, the machine returned to full operational status and completed a 300-acre clearing project without further issues.
Final Reflections
The Komatsu D58 remains a durable and capable crawler dozer, but its mechanical steering system demands attention and care. Steering problems are often gradual, masked by operator compensation or high RPM use. By understanding the system’s architecture and maintaining its components, owners can preserve performance and avoid costly downtime. In an age of electronic diagnostics and hydrostatic drives, the D58 stands as a reminder that well-built mechanical systems, when properly maintained, still have a place in the field.