KomStat vs KomStat II in Komatsu Dozers and the Evolution of Control Systems

[MikePhua]

The Rise of KomStat and Its Role in Dozer Control
KomStat is Komatsu’s proprietary electronic control system developed to manage engine performance, hydraulic response, and transmission behavior in mid-sized dozers. Introduced in the early 2000s, KomStat was designed to optimize fuel efficiency and reduce operator fatigue by automating throttle response and load sensing. It marked a shift from purely mechanical control to integrated electronic logic, allowing machines like the D37 and D39 to adapt dynamically to terrain and workload.
However, as with many first-generation systems, KomStat had limitations. Operators reported occasional lag in response, inconsistent throttle modulation, and sensitivity to sensor degradation. These issues prompted Komatsu to refine the system, resulting in the release of KomStat II around 2006–2007.
Terminology Annotation

• KomStat: Komatsu’s first-generation electronic control system for dozers, integrating engine and hydraulic management.
  
• KomStat II: The second-generation version with improved reliability, faster processing, and better fault tolerance.
  
• Load Sensing: A system that adjusts hydraulic output based on resistance encountered during operation.
  
• Throttle Modulation: Electronic adjustment of engine RPM based on operator input and machine load.
  

Key Differences Between KomStat and KomStat II
KomStat II introduced several upgrades over its predecessor:

• Improved sensor architecture with better shielding and moisture resistance.
  
• Faster processor for real-time adjustments to hydraulic and engine parameters.
  
• Enhanced fault detection and diagnostic capabilities.
  
• Smoother throttle transitions, especially during blade engagement and travel.
  

Operators who transitioned from KomStat to KomStat II noted a more intuitive feel, especially in fine grading and slope work. The machine responded more predictably to joystick input, and engine RPM held steadier under variable loads.
Field Performance and Operator Feedback
In real-world applications, the difference between KomStat and KomStat II becomes evident during precision tasks. For example, when pushing wet clay on a slope, KomStat-equipped dozers sometimes hesitated or surged due to delayed feedback. KomStat II machines maintained consistent blade pressure and smoother travel, reducing the need for manual correction.
One contractor in Kentucky reported that his D39EX with KomStat II had over 4,200 hours and still performed reliably. He previously owned an early D39 model with KomStat and found the newer system more responsive, especially when transitioning between forward and reverse under load.
Model Compatibility and Transition Timeline
KomStat II began appearing in Komatsu dozers around 2006, with models like the D37EX-21 and D39EX-21A being among the first to adopt it. Earlier models, particularly those built before 2005, typically used the original KomStat system. The transition was gradual, and some machines in the field may have hybrid configurations depending on production batch and regional specification.
When evaluating a used dozer, check the serial number and control panel layout. KomStat II machines often feature updated display modules and more refined joystick assemblies.
Recommendations for Buyers and Fleet Managers

• Prioritize KomStat II-equipped machines for precision grading and high-cycle operations.
  
• Inspect sensor harnesses and connectors for wear—KomStat II is more tolerant but still benefits from clean signals.
  
• Use diagnostic tools compatible with KomStat II to access fault codes and performance logs.
  
• Train operators on the nuances of electronic control—smooth input yields better results than aggressive toggling.
  

If purchasing a D37 or D39, confirm the control system version with the seller. Machines with KomStat II may command a premium but offer long-term savings in fuel and maintenance.
Closing Reflections
The evolution from KomStat to KomStat II reflects Komatsu’s commitment to refining machine intelligence. While both systems serve the same purpose—balancing power and precision—the second generation delivers a more seamless experience. For operators who demand responsiveness and reliability, KomStat II is a meaningful upgrade. Whether cutting grade on a highway project or clearing timber roads, the right control system makes every pass smoother, every shift smarter, and every hour more productive.