August 2, 2010 8:45 AM, EDT

DTNA’s Daum Defends SCR, Rebuts Navistar’s Criticisms

By Jonathan S. Reiskin, Associate News Editor

This story appears in the Aug. 2 print edition of Transport Topics.

The top Daimler Trucks executive in North America last week defended use of selective catalytic reduction to meet federal emissions requirements, rebutting claims by Navistar Inc. that SCR engines do not meet environmental standards because their emissions controls can be overridden by using plain water in place of a urea-water solution.

Martin Daum, chief executive officer of Daimler Trucks North America, said Navistar’s evidence for its claim was based on illegal tampering and fraud that are inconsistent with real world operations.

Daum spoke with Transport Topics reporters and editors on July 28.

He said DTNA is enjoying market-share growth in the heavy-duty truck market this year because the manufacturer has been “first to market” with engines that comply with the U.S. Environmental Protection Agency’s 2010 emissions rules. Daum said DTNA’s brands have delivered 4,000 heavy-duty trucks with 2010-compliant engines and have a backlog of 12,000 to be built.

In contrast, he said, Navistar “did the wrong step” in choosing exhaust gas recirculation technology to meet EPA’s standards for diesel engines in its International trucks, and that Navistar is trying “to gain time until it can catch up.” Daimler and the other major U.S. original equipment manufacturers chose SCR over EGR.

Daum’s conference call interview marked his nearly 14 months as CEO of the company that builds Freightliner, Sterling and Western Star trucks, and Detroit Diesel engines.

It was his first meeting with the press since Navistar screened a 15-minute video at a workshop sponsored by state and federal environmental regulators in El Monte, Calif. (click here for previous story).

In Navistar’s video, a driver said he drove a Freightliner Cascadia tractor with a DDC engine 12,000 miles, using water in place of diesel exhaust fluid, the urea-water solution necessary for SCR to work properly.

“You have to tamper with a truck and act fraudulently to do what they did. I haven’t seen a single customer do what they’ve done,” Daum said, describing the disincentives a driver would have to endure to operate a truck in such a way.

Without DEF, he said, sensors in the exhaust system key beeping alarms and blinking lights on the dashboard and limit truck speed to 55 miles per hour. For people who truly hate vehicle laws, he said, it is also theoretically possible to remove diesel particulate filters and seat belts, but such steps would be extremely improbable and irrational.

“You can do all sorts of things to break laws, but that is not our intention or our customers’, ” he said.

Daum also said Daimler’s Detroit Diesel engines are similar to Cummins Inc. power plants in having two types of sensors. A fluid level sensor in the DEF tank measures gallons but not what the fluid is. The second sensor system monitors nitrogen oxide levels in the exhaust before and after it passes through the SCR converter.

If there is not enough reduction in NOx, those sensors begin a de-rating of the engine, causing it to lose substantial amounts of power, Daum said.

Despite the allegations of fraud and tampering, Daum did concede that the de-rating procedure could be accelerated in 2011 trucks. The purpose of the El Monte workshop, regulators said, was to see if SCR engines turn themselves off quickly enough, but safely, if they are not operating properly.

Daum said his vehicles are “the cleanest trucks out there and the most fuel-efficient” and that they meet the new federal standards without using emission credits. He chided Navistar for still not having shipped any 2010-compliant engines yet — even though the company will be using federal emission credits allowing the generation of higher NOx levels.

“We have been unable to get our hands on an EPA ’10-compliant truck from Navistar for testing. . . . We have a Peterbilt, a Kenworth and a Volvo for tests, but the Navistar truck is missing. At this point, I would pay more than list price to get one,” he said.

DTNA and Navistar are the two market-share leaders in heavy-duty U.S. trucks. For the first half of this year, Daimler’s three brands — Freightliner, Western Star and Sterling — had 33.9% of the market, while Navistar’s International brand had 28.9%, according to