DC Velocity - September 2013

standards, Mayes says. The Tier 4 final regulations reduce NOx emissions by 94 percent compared with the Tier 1 standards.

That last mandate, as they say, is a doozy: According to
the lift truck manufacturers we spoke to for this article,
moving from Tier 4 interim to Tier 4 final compliance will
be difficult and expensive. “The EPA’s objective is that what-
ever we shoot out of the exhaust should be cleaner than
what we take in,” says Tim Webb, manager, product devel-
opment for Hyundai Construction Equipment Americas
Inc. “Everybody can get to that, but the problem will be the
components and the cost for modification of the diesel
engine.”
Compliance deadlines are keyed to engine output in kilo-
watts (also expressed as horsepower). For lift trucks rated
up to 75 hp, the Tier 4 final standards went into effect Jan.
1, 2013. The deadline for engines rated between 174 and
750 hp is Jan. 1, 2014, and for those between 75 and 173 hp,
the deadline is Jan. 1, 2015. Only engines manufactured on
or after those dates are affected.

DESIGN CHALLENGES

For lift truck manufacturers, the challenge is to redesign
their products to comply with the regulations but without
compromising fuel efficiency, performance, or durability.

Most of the lift truck makers are partnering with engine manufacturers such as Cummins, Perkins, Kubota, and Deutz. (A notable exception is Toyota, which is producing its own Tier 4 final engine.) The engine manufacturers are using a variety of technologies to meet emissions requirements. The most common include:

▪ Selective catalytic reduction (SCR) systems, which break down NOx into nitrogen and oxygen by mixing a reagent (called diesel exhaust fluid, or DEF) into the exhaust gas flow in a catalytic converter.

▪ Exhaust gas recirculation (EGR), which dilutes the oxygen in the combustion chamber, lowering the combustion peak temperature and reducing the formation of NOx. The lower temperature increases particulate matter, which must be filtered out.

▪ Diesel particulate filters (DPF), which trap particulate matter from the exhaust and burn it off to prevent soot from being released into the air.

▪ Diesel oxidation catalysts (DOC), which convert carbon monoxide and hydrocarbons to water vapor and carbon dioxide.

▪ Turbochargers, which help small, lower-emission engines generate more horsepower.

Each lift truck manufacturer must decide which combination of technologies will work best with its models and the applications for which they were designed. Hyundai, for example, will use diesel particulate filters in its 1.5- to 3.3-ton trucks and a diesel oxidation catalyst/selective catalytic reduction combination for larger trucks. Mitsubishi Caterpillar Forklift America Inc. (MCFA) chose diesel particulate filters for its Cat lift truck and Mitsubishi forklift truck lines. For its largest trucks, Hyster will use exhaust gas recirculation with a diesel particulate filter. Toyota’s 8- Series trucks feature a new electronic common-rail fuel injection system that works with an intercooled turbocharger and a diesel oxidation catalyst. And Crown Equipment’s Hamech V811 Series trucks are equipped with a diesel oxidation catalyst system. (See sidebar for a list of some of the Tier 4 models that are now available or will be rolled out shortly.)

The regulations have created some design challenges for lift truck manufacturers, says Jason Provancher, director of IC (internal combustion) product development and engineering at Crown Equipment Corp., which makes diesel-powered lift trucks under its Hamech brand. Components like the canister-shaped diesel particulate filters and the containers required to hold and burn oxidation catalysts take up space inside a truck, and it can be difficult to make room for them in a small lift truck, he notes. Manufacturers may also have to redesign the inner workings and exterior cowlings and panels to accommodate changes in the size and positioning of exhaust pipes, hoses, cables, and other components, says Lucas Dumdie, a product line manager at MCFA.

34 DC VELOCITY SEPTEMBER 2013 www.dcvelocity.com
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Where to learn more

There are many information resources available that explain the complex emissions control regulations for lift trucks. Here are some we found helpful:

▪ The U.S. Environmental Protection Agency Emission Standards Reference Guide for compression-ignited nonroad vehicles provides an overview and includes links to the regulations for lift trucks. ( www.epa.gov/ otaq/standards /nonroad/ nonroadci.htm)

▪ Tier 4 Emissions FAQ: Navigating the Emissions Environment, published by Cat Lift Trucks, is a helpful basic reference. ( www.mcfa.com/tasks/sites/_cat/assets/ File/Tier4brochure.pdf)

▪ The California Air Resources Board’s “Diesel Programs and Activities” page includes everything you need to know about California’s emissions restrictions. ( www.arb.ca.gov/diesel/diesel.htm)

▪ The Cummins Engines Tier 4 microsite answers questions clearly and succinctly. ( http://cumminsengines.com/ tier-4-final)

▪ Hyster’s “2011 Tier 4 interim/Stage IIIB Emissions Standards” white paper explains and compares the different emissions control methods. ( www.hyster.com/ uploadedFiles/Hyster/PDFs/North-America/White_Papers/ HysterTier4WhitePaper.pdf)