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The Komatsu SAA6D125E-7 engine is EPA Tier 4 Final emissions certified and provides exceptional performance while reducing fuel consumption. Based on Komatsu proprietary technologies developed over many years, this new diesel engine reduces nitrogen oxides (NOx) by more than 80% when compared to Tier 4 interim levels. Through the in-house development and production of engines, electronics, and hydraulic components, Komatsu has achieved great advancements in technology, providing high levels of performance and efficiency in virtually all applications.


Komatsu auto idle shutdown automatically shuts the engine down after idling for a set period of time to reduce unnecessary fuel consumption and exhaust emissions. The amount of time before the engine is shutdown can be easily programmed from 5 to 60 minutes.


Power mode (P Mode)
Appropriate for higher production jobs and uphill hauling applications. The power mode increases the engine maximum output and raises the upshift and downshift engine speeds during operation. 

Economy mode (E Mode)
Appropriate for lighter work on flat ground. The economy mode lowers the engine maximum output along with lowering the upshift and downshift engine speeds during operation.

The HM300-5 has a heaped body capacity of 17.1 m3 22.4 yd3. The low loading height of 2830 mm 9'3" enables easy loading. The body is built of high strength, wear-resistant steel with a Brinell hardness of 400 and the body shape provides excellent load stability. HM300’s frame employs a rigid box structure utilizing high tensile strength steel, and is rugged enough for the toughest jobs.


The Komatsu designed electronically controlled transmission called K-ATOMiCS has been a success in Komatsu’s dump trucks. The electronic clutch modulation system ensures proper clutch pressure when the clutch is engaged. The total control system controls both the engine and the transmission by monitoring the vehicle conditions. This high technology system assures smooth shifts with minimal shock and maximizes the power train life.


The KTCS was developed by Komatsu to allow for maximum machine performance in soft and slippery ground conditions. Komatsu leveraged its prior experience with the traction control systems in bulldozers and rigid dump trucks to develop this system for use in articulated dump trucks. 
The KTCS monitors the wheel speeds on the front and middle axles. If the system detects wheel slip, it will automatically engage the inter axle lock to improve machine performance. If the machine continues to detect wheel slip it will brake the wheel that slip was detected on. It will continually monitor the wheel speeds and engage the brakes as necessary. 
KTCS is automatically activated and deactivated. The inter-axle lock can also be engaged by the operator via a rocker switch located on the dash panel.

A payload meter is included as standard equipment on the new HM300-5. The payload tonnage is displayed on the Machine Monitor and is visible to the haul truck operator. An external display lamp mounted on the top of the cab communicates payload status to the loader operator. The external display lamp indicator lights are visible from both sides of the truck so it is always in sight of the loader operator.

PLM data is transmitted by KOMTRAX and can be accessed via the internet. Detailed data is stored in the truck’s controller and can be directly downloaded from the truck to a PC.

The rear view camera and monitor are equipped as standard.


Wet multiple-disc brakes with proven performance in other Komatsu dump trucks are tailored for use in the HM300-5. The large-capacity, continuously cooled, wet-multiple disc brakes also function as a highly responsive retarder which gives the operator greater confidence at higher speeds when travelling downhill.

The monitor panel provides guidance to the operator to help promote energy saving operation. For example, if the operator stops the machine for a long period of time with the engine idling, the message “Avoid excessive engine idling” is displayed on the monitor panel. The ECO guidance function displays six (6) messages:
  • Avoid Excessive Engine Idling
  • Release the Hoist Lever
  • Operating the Accelerator Pedal with Brake Actuated Lowers Fuel Economy
  • Shift Up
  • Avoid Operating the Accelerator Pedal with the Body Moving Down
  • Avoid Hard Use of Steering

The ECO gauge indicates a momentary fuel consumption rate during operation.

Operating the machine by keeping the gauge within the green zone leads to energy-saving operation.

The oil filters of the transmission and the brake systems can be serviced from ground level.


Located to the rear of the fuel tank, and easy to access.


The cab can be tilted rearward by 29 degrees to provide easy access to the engine and transmission for service. Electrically-operated cab tilt is standard.