BY now, the industry has scrutinized, analyzed, and debated ad nauseum the merits and drawbacks of selective catalytic reduction (SCR) and advanced exhaust gas recirculation (EGR).
We also know that Cummins, Detroit Diesel, Mitsubishi Fuso, General Motors, Hino, Isuzu, Mack, Volvo, and others are going with SCR, while Navistar is going with EGR.
But what does it mean for the tank repair shops and other vendors that install truck-mounted cargo tanks and other equipment on truck chassis? What are the additional challenges in body- and equipment-mounting? What can be done with the diesel exhaust fluid (DEF) tank? What are the concerns about engine cooling and increased vehicle complexity?
Here's a look at seven leading chassis manufacturers and the issues related to mounting equipment on chassis that meet 2010 emissions requirements.
Freightliner
Randy DeBortoli said the Business Class M2-106 and M2-106V have “switchback understep” vertical and horizontal systems. There is a clear back-of-cab solution with a six-gallon DEF tank and 50-gallon fuel tank, the lowest weight medium-duty aftertreatment system, multiple available tailpipes, and a clear right-hand PTO solution.
The daycabs' vertical tailpipes will have right- and left-hand B-pillars, while the horizontal tailpipes will have a short outlet and right- and left-hand turnouts. The extended cabs and crewcabs' vertical tailpipes will have right- and left-hand C-pillars, while the horizontal tailpipes will have a short BOC outlet and right- and left-hand turnouts.
“Although the location of the SCR and DPF systems are set, we will be publishing guidelines for exhaust tailpipe configurations to allow easier body builder retrofit or modifications to meet our guidelines,” he said.
On the heavy-duty DV 13, a mid-chassis mounted one-box also will be available, housing both the DPF and SCR catalysts and mixing chamber for the DPF.
On the M2-106/M2-106V, the vertical ATS system offers a clear below-frame solution, high fuel capacity, a clear PTO solution, and similar back-of-cab protrusion to the '07 DPF.
On the M2-106, the DEF tank is located aft of the rectangular fuel tanks. The clear back-of-cab solution includes a six-gallon DEF tank, 50-gallon fuel tank, right-hand understep ATS.
Kenworth
The primary impact of 2010 on customers will be modifications (if necessary) to accommodate the SCR canister, as well as a DEF tank, said Samantha Parlier, Kenworth vocational marketing manager.
“Kenworth engineering has worked diligently to minimize the impact of these components to all customers, and a number of designs benefit the propane and petroleum markets,” Parlier said. “If you could mount a body with 2007 emissions, you can still mount it with 2010 emissions.”
Kenworth's packaging of the DEF and SCR system underneath the passenger side cab access step (where the DPF is located today) makes the addition of the SCR canister transparent to customers. In fact, the packaging of the two canisters takes up less space than the DPF did with 2007 emissions chassis. Kenworth does offer a horizontal system, with the DPF underneath the right-hand rail and the SCR underneath the left-hand rail. Kenworth will also offer a vertical system with both the DPF and SCR mounted behind the cab.
Parlier said customers should consult with their Kenworth dealer sales representative to determine the best exhaust system for their applications.
Kenworth offers a wide array of DEF tanks for 2010. For customers concerned about frame space and weight impacts, there are several lightweight options that provide true clear back of cab. Kenworth's frame-mounted tanks will be available in a small (9 gallon), medium (18 gallon), and large (27 gallon) capacity — providing enough DEF for up to 450 gallons of fuel. Customers can specify which side of the truck they would like the DEF tank mounted on. This can be a time- and cost-saving option for customers with their own bulk tank supply of DEF.
The addition of the SCR and DEF tank will impact weight, and depending on the options chosen by the customer, the impact could range from 250 to 500 pounds (including the weight of the DEF itself) for customers who want to carry the maximum amount of DEF on board.
In order to ease the transition for customers, Kenworth developed a 2010 Body Builder Manual that includes detailed information on frame layouts, DEF tanks, exhaust options, and more. Customers and body builders should see their local Kenworth dealer to obtain a copy of the manual.
Peterbilt
PACCAR is working with DEF distributors to ensure a nationwide availability. DEF will be widely available at truck stops and other fueling outlets, as well as truck OEM dealerships. The North American industry will also likely follow European practice, where many fleets purchase bulk tanks for additional availability. In addition to a range of bulk volumes, DEF will also be available in small containers of approximately 2½ gallons to easily carry on the vehicle.
The SCR system includes sensors to monitor operational performance. Warning indicators will inform the driver of items requiring attention. For example, as the DEF tank approaches empty, the driver will receive a number of indications, providing ample time to refill the tank before it becomes empty. When the tank is almost empty or an unapproved fluid is used in the DEF tank, the engine will automatically derate.
The DEF tank is easy to refill. When filling from bulk storage tanks, a unique nozzle fits directly into the tank, which is clearly identified with a blue cap. The DEF tank filler neck is smaller than that used on the diesel fuel tank, preventing accidental contamination. Smaller, transportable containers of DEF use flexible filler hoses and funnels with spill-free nozzles.
The SCR system components are integrated with the vehicle chassis. Vehicle packaging for these components is dependent upon exhaust configurations specified and the application. For example, in a typical vehicle, the DPF and SCR catalysts will most likely be positioned within the toolbox mounted under the cab. The catalysts each perform a specific function in the aftertreatment process: The DPF is used in all diesel engines to reduce particulate matter (engine soot); the SCR catalyst facilitates the chemical conversion of NOx to Nitrogen gas and water vapor.
The DEF tank will be mounted on the chassis in front of the fuel tanks in most configurations where refilling is simple and there is no interference with aftermarket-related modifications that occur behind the cab and/or sleeper.
The tank and injection components each perform a specific function in the aftertreatment process: Tanks will store the DEF solution on the vehicle and be available in a range of sizes dependent upon total vehicle diesel fuel volume; the dosing pump provides pressure to send the DEF solution from the tank to the doser; the DEF doser delivers the DEF into a mixing pipe where it is combined with the exhaust gas exiting the DPF.
Hino
Glenn Ellis said the changeover will take place in February 2010 at Hino's West Virginia plant. Initially, Hino will offer two SCR configurations: standard and clean C/A. Hino also will introduce a new cab design. All 177 Hino dealerships will carry DEF.
He said Hino trucks will consume DEF at a rate of 1% (average) to 2% (maximum) of the fuel consumption. As part of the EPA requirement, DEF refilling must have a minimum ratio of 2:1.
The same DEF tank will be used for all Hino trucks regardless of the fuel-tank size.
The new system will add 176 pounds to the chassis.
The fuel tank has been located back-of-cab and the DEF SCR system is mounted underneath.
Navistar
Chet Ciesielski, Navistar chief engineer of severe service products, said Advanced Exhaust Gas Recirculation (EGR) is “an easy solution for all body builders” because there are no radical hardware additions; no Urea tanks or worries about availability of Urea; no additional catalysts, sensors, gauges, or electronics; no additional fluids required; service technicians understand and know how to service EGR-based products; and truck-equipment manufacturers do not have to re-engineer bodies and functional components to accommodate new hardware and packaging.
In addition, with EGR systems, there are no additional components or weight and no concerns with Urea distribution. All chassis configurations are maintained, and operational maintenance and serviceability issues are reduced.
Because MaxxForce Advanced EGR handles emissions reduction inside the engine, there's no additional after-treatment equipment that adds significant weight to the chassis. This means customers will not have to reduce their payload.
On the DuraStar, there are left and right side mega brackets to hold a slightly larger cooling module, growing from 717 square inches to 1045 square inches. The same exhaust options today will be available in 2010.
The WorkStar 7400/7500 features a high cab position about 4” taller, going to the same height the 7600 is now. The cooling module increases from 1,225 square inches to 1,590 square inches, with the same exhaust options as currently available.
Volvo
Volvo Trucks has selected SCR as its EPA 2010 design solution. This design will use the same base engine and diesel particulate filter (DPF) as the EPA 2007 design with the addition of an SCR system as part of the DPF, according to Frank Bio, product manager-trucks for Volvo Trucks North America.
Between the DPF and SCR, there is a DEF injection system. The system injects DEF into the exhaust stream; the heat causes the DEF to change to ammonia and the ammonia, together with the SCR catalyst reduce the NOx to 0.2 g/bhp/hr. The DPF removes the soot by changing it into ash as it does today.
“The difference in the DPF for EPA 2010 is that Volvo will use the NOx to convert the soot to ash, where in the past we depended on the seventh injector to spray diesel on the filter to increase the heat to turn the soot into ash,” Bio says. “Because of this adjustment, Volvo Trucks has announced the No Active Regen engine for EPA 2010. This means that in normal operating situations, there will be no need for driver intervention or for them to conduct a parker regeneration of the DPF.”
The addition of the DEF for EPA 2010 means that there is a tank and pump system added to the chassis. This tank will typically be 18.5 gallons and located on the left side of the chassis, directly behind the battery box. The system will use 2-4% DEF per gallon of fuel, meaning the tank will need to be filled just once, every second or third filling of the fuel tanks.
The lines going from the tank to the injector system on the right side of the truck are electrically heated. The lines are purged each time the truck is turned off to reduce the chance of freezing. The injector is heated using engine coolant and maintains a few ounces within the injector that is used at startup for the first injection.
He said vocational trucks are also available with smaller tank sizes and DEF tanks integrated into the fuel tank to enhance frame space. Rectangular fuel tanks are also available to assist in packaging for highway tractors where high fuel capacity/short wheelbases are customer-driven.
The SCR is mounted either on the frame behind the DEF injection system or directly behind the cab in a vertical arrangement. The frame-mounted system allows for single or dual-exhaust configurations in standard or bright finish. Dry weights (without DEF) will increase between 265 and 335 pounds for frame-mounted SCR.
Mack
Addressing concerns that a driver/operator could run out of DEF, Dave McKenna, Mack director of powertrain sales and marketing, said he believed it would take a conscious effort to run the DEF tank dry. Just two to three gallons of DEF is required for every 100 gallons of fuel. Mack has furnished a DEF level gauge in the “A” panel directly in front of the driver. It works similar to the fuel gauge, and includes a low-level indicator lamp, then an audible tone if the DEF level gets low. Depending upon engine duty cycle, the operator will get between 220 and 280 miles per gallon of DEF.
Below a 25% reserve, the DEF gauge indicator lamp illuminates. Below a 12% reserve, an audible tone sounds, alerting the driver/operator of low DEF.
Mack has successfully been running SCR systems on prototype trucks since 2003 in North America, logging over three million miles of customer testing on more than 30 trucks. The technology is already being successfully used on hundreds of thousands of trucks in other parts of the world, with billions of accumulated miles. And assembly of actual customer production trucks is already underway at the Mack Macungie plant outside of Allentown, PA.
“Our engineers really did an excellent job with the packaging,” McKenna said. “We conducted body builder clinics and incorporated their input. And our plans include a variety of DEF and fuel tank sizes, shapes, and arrangements, tailored to the specific application.”
Ford
Rob Stevens said that while the fundamentals are the same for all of Ford's emissions systems, the actual hardware can be unique between offerings. Ford's medium-duty truck offerings will have Cummins engines and aftertreatments and use hardware similar to the rest of the industry. The modifications allowed are determined by Cummins, and will be about the same for all truck manufacturers.
Under normal operating conditions, the DEF should not require filling by the operator, per EPA replenishment guidance. For complete vehicles and related applications, the DEF tank and fill are located together with the diesel fuel tank and fill on the driver's side. For chassis cabs and cutaways, the DEF tank is located on the right side of the frame behind the cab and the fill may be located to best suit second-unit body installation.
The DEF warning system includes a series of audible warnings and cluster messages starting at 1,000 miles. Inducement of progressive performance degradations begin at empty. Similar warnings are used with the detection of unsatisfactory DEF.