Off-Highway Aftertreatment Systems in North America, Europe, Korea and Japan

Off-highway equipment, such as construction and agricultural machinery, must comply with strict emissions regulations worldwide. These rules aim to significantly reduce nitrogen oxides (NOx) and particulate matter (PM). In regions like North America, Europe, Korea and Japan, these standards are continuously evolving, driving advancements in aftertreatment technology.

Cummins Emission Solutions (CES) leads in making exhaust aftertreatment systems that meet these high standards. Our technology helps customers comply with current regulations and prepare for future ones.

Available Technologies for Emission Control

To meet stringent emission requirements, manufacturers use a range of aftertreatment technologies: 

• Diesel Oxidation Catalyst (DOC): Reduces PM and enables DPF regeneration while requiring minimal maintenance.
• Diesel Particulate Filter (DPF): Captures fine particles created during the combustion process in the engine. DPFs help reduce both the mass of particles (PM) and the number of particles (PN) in the exhaust. It also periodically regenerates to maintain system efficiency. This component is the key to meeting the EU Stage V stringent PN regulation.
• Selective Catalytic Reduction (SCR): Reduces NOx emissions using urea-based Diesel Exhaust Fluid (DEF).
• Ammonia Delivery System: Ensures optimal DEF injection and urea decomposition into ammonia to achieve over96% NOx reduction in the SCR needed to meet the low NOx emission requirements. 
• Hydrocarbon Dosing System: While most modern Diesel engines can inject hydrocarbons in-cylinder, Cummins Emission Solutions offers additional hydrocarbon dosing systems. These enhance regeneration and thermal management when system optimization requires it.  

These components work together within a complete aftertreatment system, maintaining high engine performance. Cummins leverages its engineering expertise and market-leading innovations to meet global emission standards while optimizing operational efficiency.

Certifications and System Variability

One of the key challenges in off-highway applications is the need for multiple certifications across different regions. Here’s how aftertreatment solutions address these challenges:

• Different systems for different engines: depending on their size and amount of SCR they use, engines have different set ups
  • Smaller engines (below 74HP/56kW): these can usually use simpler systems like a DOC and DPF without an SCR
  • Larger engines (74hp to 750 hp): these usually require a full setup with DOC, DPF, and SCR to meet stringent NOx limits. 
  • High horse-power engines (over 751 hp): given the stringency of these regions, SCR is often required to meet the NOx limits even for very large machinery.
• Regional differences in emission standards: 
  • Particulate control:  EU Stage V and Japan have the strictest standards, limiting the number of particulates in the exhaust (PN limit). This requires using Diesel Particulate Filters (DPFs) in all systems. In contrast, EPA and Korea focus only on particulate mass (PM), allowing some systems to meet standards without a DPF by relying on engine tuning.
  • NOx control: The NOx limits are uniform across North America, Europe, Japan and Korea. However, their testing methods differ, especially in how they wight cold vs. hot emissions.  
  • North America’s stricter requirements: the: Environmental Protection Agency and California Air Resources Board have stricter requirements to prove that systems maintain their emission performance through their useful life. This means more development and testing is needed to meet standards.

The Challenge of Broad Application Requirements

Off-highway equipment faces tougher conditions than on-highway vehicles. These machines operate in various environments, from dusty fields to freezing temperatures and high altitudes. Cummins’ modular aftertreatment solutions are designed to be flexible and robust. They fit into tight spaces while maintaining performance. Our Flex Module™ helps customers meet space constraints and still achieve optimal NOx conversion. These systems are built for durability, minimizing downtime, reducing operating costs, and improving overall cost of ownership.

Another approach is the Cummins’ Modular Aftertreatment System which is designed to be flexible, adapting to different applications to ensure compliance while keeping costs and durability in check. Our advanced catalyst technologies enhance NOx conversion efficiency, and the UL2.2 Urea Dosing System is built for easy service and less maintenance downtime.

Future of Off-Highway Aftertreatment Systems

With evolving emissions standards, manufacturers must continuously innovate. Cummins is leading the way by:

• Developing next-generation SCR and DPF technologies to improve efficiency and reduce costs.
• Leveraging modular architectures to simplify compliance across multiple regions.
• Enhancing durability to withstand vibration, thermal cycling, and contamination in harsh environments.
• Integrating smart sensors and controls to optimize regeneration and reduce maintenance downtime.

 As global regulations tighten, aftertreatment technology will continue to advance. Cummins invests in scalable, high-performance solutions to ensure off-highway equipment remains reliable. Our advanced technology, global manufacturing, and expertise make us a trusted partner for long-term emission solutions.