How Tier 4 Technology has Changed the Engines for Compact Excavators
by David Steger, Takeuchi-US Product Manager
It has been one of the most widely discussed and confusing topics in our industry over the past few years: Tier 4 technology. U.S. EPA FINAL TIER 4 engine emission regulations have certainly been a game changer for users, renters, owners, dealers, and yes, even manufactures.
Most machines have similar technology until you get in the three- to four-ton sizes, where you see the engine power threshold for exhaust after treatment requirements. Historically speaking, there are many machines right at the 3.5-ton threshold. There are manufacturers that continue to keep the size of this machine, but choose to go with a smaller engine to stay under the EPA threshold of 25.4 hp (19kW). Going with a lower powered engine will naturally reduce the overall cost for operators because it does not require the more expensive engine control systems, nor does it have any exhaust after treatment devices. Unfortunately, by renting or buying a machine of this nature will under power the excavator, which typically results in a reduction of both performance and productivity. Depending on your needs, the reduction in power could very well reduce your bottom line.
The better option is to choose a manufacture like Takeuchi that designs a more powerful and capable machine, which is still easy to transport. The TB240 falls in the 3.7- to 4.0-ton range, and in some cases have the capability of previous models that were in the 4- to 4.5-ton range. We have also increased the capability of our smaller TB230 excavator to help align with other machines found in the 3.0 to 3.3 ton range. This concept offers the customer a choice: maximum value with good performance (TB230) or maximum performance with excellent capability (TB240), while still delivering good value.
Engines with exhaust after treatment systems are also computer controlled and have more complex fuel systems, making fuel quality and cleanliness more important than ever. The after treatment approach may also differ slightly per the manufactured excavator; some use a Diesel Oxidation Catalyst (DOC) to control emissions while other manufacturers use the DOC plus a Diesel Particulate Filter (DPF) to further scrub the exhaust. While the DPF may have period maintenance requirements including regeneration, it often is the most reliable system for long-term emission reduction.
Regeneration is associated with diesel engines equipped with DPF exhaust after treatment. The DPF is a filter for the exhaust, much like the air cleaner is a filter for the intake air. As the filter becomes plugged it is more restrictive and needs to be cleaned. Regeneration is a cleaning process that is used to “burn off” carbon particles in the exhaust filter. Most often the regeneration occurs automatically during normal operation without the operator even knowing. In some instances though, the machine may require a parked regeneration, which requires the machine to be stationary for a short period of time while the machine completes a thorough cleaning (regeneration) to restore the effectiveness of the exhaust filter. Diesel Exhaust Fluid (DEF) is common on larger trucks and equipment; however, it does not exist on compact equipment under 75 hp, and will not exist any time soon. Engines below 75 hp (56 hp) will not require DEF however you will begin seeing DEF in larger excavators and other types of compact equipment that have engines above 75 hp (56 kW) as early as this year.
Make sure, when renting or buying a compact excavator that you know your options and have a full understanding of the engine emissions. The more you know and understand, the better results you will have out on the jobsite. If you have any questions, refer to your excavator manual or talk to your local Takeuchi dealer.