It's Time to Talk Regeneration

Active DPF regeneration with '07 engines.

"Why would you want some level of indication to come on (that isn't normally on) to let you know things are running normally?" Goode says.


When the lamp illuminates under standard conditions, the DPF must be regenerated within two to six hours of operation; if the lamp is flashing, it also must be regenerated, at which time engine power may be automatically reduced. Documentation from Cummins suggests changing to a more challenging duty cycle, such as highway driving, for at least 20 minutes, or performing a 'parked' regeneration.

With this, there may be concern about interruption in duty schedules, but Goode says there is "such a minor, minor incident of it ever happening on a fleet-type operation at all."

"In all of our field tests, there's only been one application that ever needed any of that, for parked regeneration to ever happen," Goode says.

In one testing phase, there was an incident in which a package delivery van required parked regeneration. Goode says drivers were required to shut the engine down at every stop, so it took the exhaust system a long time for the temperature to rise in that kind of day-to-day or start, stop and turn off work flow.

But Goode says regeneration was required in only one test phase. "That was only in one of those particular instances.

"Other trucks with the same type of duty cycle didn't have the need for the parked regeneration requirement," he says.

"It's very, very rare that parked regeneration is going to be needed. If and when it's needed, it's not a mission-disabling requirement at that time," Goode continues.

"When it's needed, you get the DPF lamp illuminated and our card says the DPF needs to regenerate within 2-6 hours of regeneration. And that's real conservative. Fundamentally, that can last you through a shift," he says, and adds that it will never lead to the truck having to be taken out of service immediately.

If it happens, Goode says that there will be ample warning for it to occur during a normal service interval, whether after a shift or the next time it can be scheduled in.

Goode says that he doesn't want to minimize the impact of the changes that have come along as part of the new EPA mandates and for introducing DPFs to the industry.

"It's another one of those events that has been played pretty big. We had been in the mode of engineering. We're through that mode and now we're in the mode of education," Goode says. "I think our company has been very responsible to make this change as invisible to our customers as possible."

With General Motors vehicles, under most circumstances the passive and active regeneration will occur as needed with their systems. Pearce says that it will essentially be transparent to the operator, should the operator never meet the condition for passive or active regeneration to occur.

"So if the vehicle sits for a long period of time at idle, and the light comes on, the intent is that the vehicle needs to be operated under conditions that will permit that regeneration, which is 30 miles per hour for 10 minutes", Pearce says.

"We think the passive regeneration is going to be a minimal need for the trucks. But the medium duty has the ability to regenerate at idle using the switch on the dash. If the amber DPF light is on, you need to make sure the vehicle is parked on a non-flammable surface, set the e-brake and turn the regeneration switch on. That will put the vehicle in a regeneration mode," Pearce continues.

He says that most of the time when the light comes on and when the vehicle is driven under normal operating conditions the next time, it's going to go through the active regeneration process.

Goode says that Cummins allows customers to use CI-4 or CJ-4 oil.

"If you use old oil, that will shorten to the 6,500 range for cleaning intervals and lower the need for cleaning the filter out because the ash buildup is electronically monitored," he says and notes the lamp will illuminate to indicate service is required.
"It's not going to be an issue of anything bad if the lamp goes on," Goode says, it is a simple reminder to schedule a cleaning at the next routine preventative maintenance service interval.

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