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 to the OEMs and body builders? 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. This information is based on a presentation given at The Work Truck Show earlier this year.
Dodge
Kevin Mets, lead engineer for heavy-duty pickup trucks and chassis cabs, said Cummins' 6.7-liter turbo diesel remains the same. He said Dodge is continuing the mantra it has been carrying for the last few years — that it wants to have the most upfit-friendly truck possible.
“When we designed this 2010 truck, our commercial vehicle team was part of all packaging meetings that went on,” he said.
He said the new parts include lines going to DEF pump and to the DEF injector and down to the SCR catalyst. The SCR module, “the brains behind the whole thing,” is mounted on the crossmember underneath the cab.
“With the cab on, most of the components are covered by the cab,” he said. “The tank is mounted under the cab. The filler pack is frame-mounted and is in a 3“ zone between the back of the cab and the closest possible location we allow the upfit to be mounted. It takes advantage of the curvature of the back of cab.
“The pump is mounted on the frame rail and is inboard of all suspension components, so it's narrow enough that it has no effect on service-body applications or toolboxes off of flatbeds. The PTO packaging area stays the same. All of that is carried over from 2009, so the packaging of the PTO should not be impacted by this new emissions package.
“As wheelbases change, the only thing that grows is the exhaust pipe after SCR. As far as consistency goes, the emissions system is the same no matter what wheelbase the system is mounted on.”
Engineering support manager Walther Bloch said the Sprinter tank is mounted under the cab and outboard of the frame rail. The fill neck is mounted to the frame and forward of the 3" plane, with no kit to install. The pump is mounted to the frame inboard of the leaf-spring bracket and there is clearance for service-body upfits.
On the exhaust side: the exhaust pipe between the turbo and diesel particulate filter (DPF) is common to 2009; the PTO environment/mountings also are common; and the SCR location relative to back of cab stays constant.
Sprinter curb weight will increase by 155 lbs for the chassis cab and 144 lbs for cargo. Due to chassis certification, Sprinters under 10,000 lbs GVWR cannot exceed the UVW and inertia weight of 7400 lbs, and Sprinters over 10,000 lbs GVWR cannot exceed the inertial weight of 10,470 lbs.
During tests, the average consumption of DEF for Sprinters was 0.6 gallons per 1000 miles. DEF service intervals are every 10,000 miles or once a year.
New engine performance is 185 hp at 3800 rpm, an increase of 30 hp; new torque is 325 lb-ft at 1400-2400 rpm, an increase of 45 lb-ft.
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.
Ford's light trucks, up through Class 5, use distinct hardware to meet the 2010 emissions requirements.
On light trucks, an SCR chamber has been added to the diesel oxidation catalyst (DOC) and the DPF. Like the 2007 system, nothing in the after-treatment progression ahead of the last device can be modified without affecting certification.
The DEF dosing module is new, and can't be relocated or modified.
The DEF tank includes a supply module, temperature and level sensor, heated reservoir, and splashing measures. The supply module recalls the DEF in the supply line when the vehicle is shut off.
The DEF is warmed, as required, to assure that it does not freeze during low ambient temperatures. The DEF spray pattern is optimized in the dosing module to promote mixing, improving the effectiveness of the SCR process. The exhaust sensors monitor the exhaust temperature throughout the process, along with the NOx levels and exhaust pressure. The engine-control modules work together with the various sensors and engine controls to assure compliance and perform system diagnostics.
Typical light-truck DEF tanks with mid-ship fuel tanks on pickups, vans, wagons, and box deletes are coupled with the fuel tank to improve storage capacities. The completed-vehicle packages do not provide much opportunity for adaptation. DEF fill kits will be available for chassis cab and cutaway offerings, similar to fuel fill kits.
Typical light-truck DEF tanks for chassis cabs and cutaways are mounted outside of the frame on the right side of the vehicle. DEF fill will be located on the left side of the vehicle across the top of the frame, but can be relocated to the right side of the vehicle to best suit the second-unit body installation. Guidelines for tank relocation are being evaluated to accommodate line constraints.
Ford's light-truck DEF tanks are sized to meet EPA DEF replenishment guidelines, and tank capacities vary by model to maintain this objective.
“Since DEF consumption is dependent on duty cycle and operator behavior, DEF replenishment may be required by the operator under some circumstances,” Stevens said. “DEF consumption is dependent on engine loads, because greater loads consume more DEF, both in terms of absolute consumption and relative to fuel consumption; and driving conditions, because steady operation consumes much less DEF than transient operations.”
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 1000 miles. Inducement of progressive performance degradations begin at empty. Similar warnings are used with the detection of unsatisfactory DEF.
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. A crossover 2HH will also be available for very short wheelbases (sweepers, ambulance, RV, etc).
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.
GM
Product manager Mike Eaves said the tank on the G van and G cutaway has a capacity of 5.83 gallons and a flexible fill hose. On van applications, the tank is outside of the frame rail within the body.
The new emissions system means that with tanks full, medium-duty vehicles will carry an additional 180 lbs.
“The good news is that there are no significant changes to the frame, axles, suspension, transmission, cooling systems, or fuel tanks,” he said.
Hino
Glenn Ellis said the changeover will take place in February 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 lbs to the chassis.
The fuel tank has been located back-of-cab and the DEF SCR system is mounted underneath.
International
Chet Ciesielski, chief engineer of severe service products, said 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 1225 square inches to 1590 square inches, with the same exhaust options as currently available.
Mack
Addressing concerns that a driver/operator could run out of DEF, Dave McKenna said he believed it would have to be a conscious effort to run the DEF tank dry. Mack has furnished a DEF level gauge in the “A” panel directly in front of the driver. It works similar to the fuel gauge, with the addition of a low-level indicator lamp and an audible tone for when there is less than 5% DEF remaining. Depending upon engine duty cycle, the operator will get between 220 and 280 miles per gallon of DEF.
Below 25% reserve, a small DEF gauge indicator lamp illuminates. Below 12% reserve, an audible tone sounds, alerting the driver/operator of low DEF.
Mack has successfully been running SCR systems on prototype trucks since 2000, logging over two million miles on 10 customer vehicles. Mack's parent, the Volvo Group, has logged more than 23 million miles of road testing in Europe. This year began production of SCR-equipped vehicles to meet the Euro 4 standards, which take effect on October 1.