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Tier 4 excavators debut

Spring 2014

 

Doosan is introducing the first two Tier 4-compliant Doosan crawler excavators this spring — the DX300LC-5 and DX350LC-5 — which will be followed by additional excavator models and Tier 4-compliant wheel loaders and articulated dump trucks later this year.

Tier 4 is the fifth set of emission standards adopted and regulated by the U.S. Environmental Protection Agency (EPA) for new non-road diesel engines. To meet strict Tier 4 emission standards, we took a systems-based clean diesel approach: internal engine modifications and after-treatment technologies. Additionally, diesel fuel advancements by oil refineries help reach Tier 4 compliance.

Internal engine modifications

We utilize diesel engines in our excavators, which include a high-pressure common rail (HPCR) system and cooled exhaust gas recirculation (CEGR). The latter varies the amount of exhaust gas recirculated back to the combustion chamber. The combustion temperature is therefore optimized to balance the reduction of particulate matter (PM) and the formation of nitrogen oxides (NOx). Benefits of the engine modifications include:

  • A variable geometry turbocharger (VGT) is utilized to optimize boost pressure throughout a wide rpm range of the engine, resulting in improved fuel efficiency at lower rpms
  • This also generates higher torque levels and faster engine response even at low rpm

For Tier 4 emission standards, we added a mass airflow sensor and exhaust brake. The mass airflow sensor allows the electronic control unit (ECU) to improve the management of airflow from the VGT, and optimize the fuel delivery to the combustion chamber based on air intake volume and rpm.

  • The exhaust brake helps to maintain consistent engine temperatures at lower engine speeds to improve operating efficiency
  • Consistent engine temperatures reduce harmful emission levels in the exhaust when the engine is running at lower rpms
  • Under normal operation, with high rpms, the exhaust brake is inactive

After-treatment technologies

Tier 4-compliant Doosan excavators will combine selective catalyst reduction (SCR) with a diesel oxidation catalyst (DOC) to reduce engine emission levels. Diesel exhaust fluid (DEF) is used with SCR technology and stored in a DEF tank near the front-left corner (opposite of the operator station) of the Doosan crawler excavators. The DOC works in conjunction with SCR to transform PM emissions into harmless water and carbon dioxide. DEF is injected into the exhaust system to help the NOx produced during combustion transform into water and nitrogen.

Advancements to diesel fuel

Working in tandem with engine modifications and after-treatment technologies, the third part of meeting Tier 4 emission standards is diesel fuel quality. Ultra-low-sulfur diesel fuel, available in grades 1-D and 2-D with sulfur levels of 15 ppm, helps to maximize the Doosan excavator's engine performance.

Excavator updates

The newest Doosan crawler excavators received some valuable updates to coincide with the Tier 4 launch. They include the following:

  • Auto shutdown
  • LCD display panel update
  • Improved serviceability
  • Auto belt tensioner: fan and air conditioning
  • Anti-skid plates
  • Emergency engine stop was relocated for easier access
  • Battery upgrades
  • New 100-amp alternator

Fuel savings

Auto shutdown helps owners save fuel during non-working conditions. When enabled, the feature will shut down the excavator's engine after a preset idle time. For example, the operator can configure the idle time from 3 to 60 minutes. For operators in California, auto shutdown helps meet the state's regulations of idling for only 5 minutes for off-highway machines.

Display enhancements

An improved 7-inch LCD display panel allows operators to continue monitoring the excavator parameters while viewing the rearview camera image. Critical machine data appears next to the camera view. With optional side cameras, a split screen allows both camera displays to be viewed at once. New additions to the monitor include the DEF gauge and fuel efficiency.

Contact your local Doosan dealer for more information about these new models. Look for more information about Tier 4 Doosan products, including wheel loaders and articulated dump trucks, in future editions of DoMORE® magazine.

 

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