EPA Tier 4
What EPA Tier 4 means to​ Manufacturers

Tier 4

Compliance is mandatory

Compliance with EPA Tier 4, or any other Federal/State regulatory requirements, is not optional. All manufacturers must comply if they wish to continue to sell diesel-powered products in this kilowatt or horsepower/performance range.

While Tier 4 may seem “new” to many in our business, The Toro Company has been working with our engine suppliers over the past decade to successfully comply with each Tier of the emission regulations. Since the compliant engines to meet progressively higher emission standards were more easily interchangeable in the past, much of the burden to implement the required changes fell on engine manufacturers. Going forward, however, incorporating new Tier 4-compliant diesel engines into turf equipment requires significant equipment redesign because the level of emission reductions mandated in this stage will require more sophisticated fuel injection/combustion systems and exhaust after treatment systems.

Exhaust After-treatment for EPA Tier 4 Solutions

Tier 4
  • In addition to more sophisticated engine electronics, the exhaust after-treatment is key to achieving EPA Tier 4 compliance. Key elements of the exhaust after-treatment systems include Diesel Oxidation Catalysts (DOCs) and Diesel Particulate Filters (DPFs).
  • The process of removing particulate matter and NOx from the exhaust starts when the exhaust reacts with a special catalyst to transform a portion of the particulate matter into harmless substances such as water and carbon dioxide.
  • The after-treatment process then pushes the remaining particulate matter into a Diesel Particulate Filter. This filter uses a special ceramic wall flow filtration process that further separates particles from the exhaust.
  • Finally, the particulate material that is collected in the DPF is cleaned and purged via a high temperature regeneration process. The “burn-off” of material during this process helps maintain the efficiency and efficacy of the filtering process. This is called DPF Regeneration.

Each of the new diesel engine/exhaust systems:

  1. require more sophisticated electronics [to monitor and control emissions]
  2. are physically larger in size, and
  3. have new and more expensive components [particularly in the exhaust after treatment area]

Significant redesigns were required to integrate the above Tier 4-compliant diesel engine changes with existing equipment/models. Examples include: retooled engine compartment housings, modifications to chassis frames, and re-engineered cooling systems to manage higher temperature exhaust, to name a few. In many cases over a third of the parts for a given model had to be reworked, replaced or otherwise re-engineered! Because of this, existing models were simply not “retrofit” capable. Toro, alone, produces over twenty diesel-powered models in the 18.6 to 55.2 kilowatt (25 to 74 horsepower) range that had to be addressed.

The obvious message, which no manufacturer wants to convey, is that the design, manufacturing and component costs – to deliver Tier 4-compliant diesel-powered products has increased significantly on machines manufactured in 2013. Cost reductions, while always a high priority in product redesigns, are not sufficient to offset cost increases.