It's Time to Talk Regeneration

Active DPF regeneration with '07 engines.

There is also a lot of flexibility within the Cummins Particulate Filter, which can be programmed to fit specifications determined by the OEM or the customer. For instance, Goode says that pre-determined values can be programmed to prevent active regeneration from occurring if a truck is going below a certain speed limit.

"This will eliminate the fear that the high exhaust temperatures are going to occur when a truck is parked at a location that may not be conducive for high exhaust temperatures," Goode says.

"In order to alleviate that occurrence and that fear, there is a programmable value to say 'I don't want regeneration to occur if the truck is going below 10, 15, 20 miles per hour.'"

If active regeneration is occurring and the truck goes below the pre-programmed speed limit amount per hour, the regeneration process will stop in mid-cycle.

"Through the sensors on a particular filter, we can say we got 50 percent of it or 60 percent of it clean, but we will reinitiate the cleaning, or active regeneration process the next time we are above that programmed speed value," Goode says.

This means that the system will pick up where it left off, or will, as Goode indicates, be "bookmarked".

For a medium-duty vocational truck, Goode says that maintenance is scheduled in a fairly wide range of intervals, typically between 6,500 and 10,000 hours.


Most DPFs will be in a similar location to where the current exhaust system is located.

According to a spokesperson from Donaldson, the placement of their aftertreatment DPFs are very similar to where the current exhaust systems are located, either under the vehicle between the frame rails, just outside of the frame rail or just behind the cab in a vertical orientation. In general there shouldn't be a need to relocate any items with their system. However, the DPFs are larger than a typical muffler, so there may be items that no longer fit, such as battery or tool boxes.

In addition, Donaldson systems will be made from stainless steel materials with a high degree of longevity, and should not have life-expectancy differences between the heavy- or medium-duty classes from an overall unit perspective.

When viewed in terms of time or number of years in the field, the only difference customers may see is with longevity.

Because medium duty trucks don't put on as many miles as the Class-8 over the highway trucks, it is not comparable in terms of miles.

On medium-duty General Motors vehicles, the DPF is designed to meet or exceed any applicable EPA requirements and is covered under the terms of the warranty, according to Ed Pearce, manager of service support.

He says that the addition of the DPF is really not different from any other kind of change made to their vehicles. The company is not suggesting the DPF be moved or relocated due to shielding and routing issues, although some of the upfitter equipment may need to be moved. But in Pearce's opinion, this will not have an impact because any changes are included in the upfitter guide.


There are also new dash lamps for trucks with the Cummins Particulate Filter. The lamps will illuminate, indicating a 'high exhaust system temperature' to tell the driver high exhaust temperatures may exist due to aftertreatment regeneration. Goode says this is when the exhaust temperature is higher than normal. Cummins has made this a variable feature.

"If the truck is en route, then the need to know that the exhaust temperature is high is irrelevant," says Goode. He explains that Cummins allows the truck manufacturer to decide if the lamp should illuminate while the driver is traveling on the highway, or when active regeneration will occur.

Goode says that while the exhaust temperature may be high because of the regeneration taking place while driving, the truck manufacturer might want to keep it 'invisible', or choose not to illuminate, to avoid alarming the driver unnecessarily.

He also explains that if a driver is parked or driving below a certain speed limit, it may be relevant for the operator to know that the active regeneration process is underway and the exhaust temperature is going to be higher than normal during this interval. But he says that decision is up to the end-user.

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