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Tier 4

Emissions Evolution For Compact Equipment

Bobcat® machines have been changing to meet emission standards for several years. Many Bobcat equipment models will go through as many as five different tiers of standards: Tiers 1-3, Interim Tier 4 (iT4) and Tier 4 (T4).

You don’t have to retrofit your machines to the current emission standards. Federal regulations require that manufacturers build machines compliant with the emission standards in effect at the time of manufacture.

Standards for diesel exhaust emissions become more stringent from tier to tier. Each tier addresses numerous types of pollutants. However, Particulate Matter (PM) and Nitrogen Oxides (NOx) receive the most attention.

  • Nitrogen Oxides (NOx) contributes to ground level ozone, commonly known as smog.
  • Particulate Matter (PM) consists of soot or unused fuel found in exhaust. This type of pollution gives dirty engine exhaust its black color.

Chart 1 explains how harmful emissions such as NOx and PM are reduced through each emission tier.

Chart 1

All Tiers - Compact Equipment
Engine Horsepower 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Less than 25 Tier 1 Tier 2 Tier 4
25 - 75 Tier 1 Tier 2 Interim Tier 4 Tier 4
75 - 175 Tier 1 Tier 2 Tier 3 Interim Tier 4 Tier 4

Tier 1 for Compact Equipment

The first set of EPA emission standards for new non-road diesel engines is referred to as Tier 1 (date range shown in chart 1). The main goal of this emission tier was to reduce Nitrogen Oxides (NOx) emissions from these engines by roughly 30%.

Bobcat machines needed only minor internal engine modifications to become Tier 1 compliant. An improved engine combustion system lowered the output of emissions, such as NOx, with little or no impact to machine price, performance or fuel economy.

Tier 2 for Compact Equipment

The second set of EPA emission standards for new non-road diesel engines is referred to as Tier 2 (date range shown in chart 1). Major focus was on NOx, hydrocarbons (HC) and particulate matter (PM). PM reductions were as much as 25% on some engines.

Direct fuel injection (DI) systems aided in further lowering emissions and were used in many Bobcat machines during Tier 2. DI also improved fuel economy and lowered average engine operating temperatures which lowered operating costs and increased engine life.

Tier 3 for Compact Equipment

Tier 3 standards applied to Bobcat models with engines of more than 75 horsepower (shown in chart 1). Tier 3 focused on reducing NOx emissions roughly 37% for these machines.

Bobcat utilized a Cooled Exhaust Gas Recirculation system, or CEGR, as a primary way to meet Tier 3 compliancy.

Extreme temperatures during combustion increase NOx produced by engines. CEGR systems lower combustion temperatures by several hundred degrees, reducing the formation of NOx.

Low-sulfur diesel, already in use for on-road vehicles, was also introduced for non-road vehicles during Tier 3. Low-sulfur fuel increases the life of CEGR system components.

Chart 2

Engine Size Currently iT4 Compliant? Currently T4 Compliant? New systems needed for iT4 compliance? New systems needed for T4 compliance?
Under 25 hp Yes Yes No No
25 - 75 hp Yes No No Yes
75 - 175 hp Yes No (scheduled for 2014) Yes Yes

Interim Tier 4 (iT4) and Tier 4 (T4) for Compact Equipment

Further reductions to NOx and PM is the main objective. Smaller engines have less stringent emission standards compared to larger engines and modest engine updates met iT4 or T4 compliancy for some Bobcat machines. Models that have yet to become compliant to iT4 or T4 will need additional technologies to do so. (See chart 2 for more detail).