Building Block Technologies

Engine Technology

  1. MORE POWERFUL, RELIABLE ENGINE ELECTRONICS
    The electronics used in Cat® Tier 4 Final engines are more powerful and robust than ever.
    Increased features and connection commonality improve the customer experience and increase quality and reliability.
  2. NEXT GENERATION FUEL SYSTEM OPTIONS
    As a key component of Cat Tier 4 Technology, injection timing precisely controls the fuel injection process through a series of carefully timed microbursts. This injection timing provides more control of combustion for the cleanest, most efficient fuel burn. To maximize customer value, Caterpillar engineers specified fuel systems based on the power and performance demands for each engine.

    High-Pressure Common Rail Fuel Systems
    with full electronic injection improve precision and control that boost performance and reduce soot for the C7.1 ACERT™ and C9.3 ACERT.

    Advanced MEUI™-C injector platforms
    handle increased injection pressures and more precise fuel rates. These durable injectors enhance responsiveness while controlling soot in the C13 ACERT, C15 ACERT, C18 ACERT, C27 ACERT and C32 ACERT.
  3. INNOVATIVE AIR MANAGEMENT
    Cat Tier 4 Final engines feature innovative air-management systems that optimize airflow and enhance power, efficiency and reliability. We apply a range of simple, reliable turbocharging solutions, based on engine size and application. This allows us to match turbo performance to rated output for high productivity, excellent fuel efficiency, long life and low operating costs.
  4. CAT NOx REDUCTION SYSTEM
    The Cat NOx Reduction System (NRS) captures and cools a small quantity of exhaust gas, then routes it back into the combustion chamber where it drives down combustion temperatures and reduces NOx emissions. The result of more than a decade of Caterpillar engineering research into this technology, the NRS is designed to be the most reliable system of its type.

Aftertreatment Technologies


Clean Emissions Module (CEM)

The CEM protects interior components, minimizes the aftertreatment footprint and simplifies maintenance.

  1. Diesel Oxidation Catalyst (DOC)
    The DOC uses a chemical process to reduce hydrocarbons and carbon monoxide in the exhaust stream. No maintenance is required because the DOC is a “flow-through” device.
  2. Diesel Particulate Filter (DPF)
    A DPF traps particulate matter that’s carried in the exhaust stream, preventing it from being released into the atmosphere. Inside the DPF, particulate matter, sometimes referred to as “soot,” is trapped until it is oxidized during regeneration.
  3. Selective Catalytic Reduction (SCR)
    The SCR system consists of a SCR catalyst, AMOX and the Pump Electronics Tank Unit (PETU). This system uses a small amount of Diesel Exhaust Fluid (DEF) to convert NOx emissions in the exhaust into nitrogen and water. No major redesign was necessary to accommodate this system into Cat machines as the space claim required did not change from our Tier 4 Interim design.
  4. Ammonia Oxidation Catalyst (AMOX)
    In order to ensure sufficient NOx reduction, a small amount of excess Diesel Exhaust Fluid (DEF) is injected into the exhaust stream. This excess DEF may pass through the Selective Catalytic Reduction (SCR) catalyst as ammonia. To prevent excess ammonia from entering the atmosphere, the exhaust gas flows through an Ammonia Oxidation Catalyst (AMOX) where the ammonia reacts with oxygen in the presence of this catalyst to form nitrogen and water.
  5. Pump Electronics Tank Unit (PETU) The PETU is responsible for storing, controlling and supplying the appropriate quantity of Diesel Exhaust Fluid from the DEF tank to the DEF injector. The Diesel Exhaust fluid is used by the SCR system to reduce NOx emissions in the exhaust. DEF is a solution of urea dissolved in deionized water to produce a concentration that is about 1/3 urea and 2/3 water. DEF used in Cat engine systems must meet the requirements outlined in ISO 22241-1.

Learn More about Diesel Exhaust Fluid


Advanced Technologies - Proven Performance

With millions of working hours on tens of thousands of units since the Tier 4 Interim product introductions, you can be confident in the quality and value of your Cat® Tier 4 Final investment. At Caterpillar, we know you’re under constant pressure to do more work at a lower total cost with less environmental impact. Our Tier 4 solutions help you do that. We redesigned the product line from the inside out, putting decades of innovation expertise to work on your behalf. The result is a new generation of engines that meets your high expectations for reliability, performance, fuel efficiency and component life, while producing significantly fewer emissions.

Learn About Advanced Technologies
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