A further enhancement of the I-Shift box is Eco-roll. With cruise control selected, if the truck is maintaining the set speed under the effects of gravity, Eco-roll will disengage the drive to the rear bogie allowing the engine revs to drop to tick-over. If power is required, the drive instantly re-engages and revs zip back up. The same happens if the brakes are applied or the set retardation speed is exceeded. The system is designed to save fuel and reduce wear and tear.
The Scania P340 8x4 tested in August had a nine-speed manual box and although it was noticeably slower around our route it did return a route average of 9.21mpg.
The truck tested here, with its 12-speed I-shift box, returned 8.83mpg as an overall average, the lowest sectional figure being 6.98mpg recorded on the testing A339 rural route between Basingstoke and the A34 at Tothill. But 7mpg is not bad in the heavy going and was compensated for by a high of 9.42mpg on the motorway.
So on balance, driving as ever for economy, we achieved better fuel results from a slightly lower powered manual 32-tonner but paid the penalty in terms of journey time; so critical for most tipper operators. But if your drivers are heavy with the right boot, racing to get in that extra load, we believe the evidence is now overwhelmingly in favour of the auto. Recent reports that Summerfield has asked Volvo to lock out the manual override on its I-Shift-equipped trucks speak volumes. In fuel economy terms, this truck's performance at the pumps is among the best we have encountered from an automatic, which must make it a serious contender for consideration.
Just a word about Eco-roll. We had no way here of proving the benefits of this system, but in theory it saves fuel. It takes time to feel comfortable with it because we are all taught never to free wheel in a heavy goods vehicle. Well Eco-roll does not actually take the truck out of gear, it electronically disconnects the drive, allowing the engine revolutions to return to idle. During our test it activated numerous times on long gentle descents - where braking or retardation is required it will not function - so if it contributed to our average fuel consumption figure all well and good. But our jury is out, awaiting more evidence.
I have always daydreamed about replacing the Jake brake with a regen braking system (so the job of holding the truck back is spread over all the wheels rather than just the drive axle(s) and some of the "G-Force" can be recovered for climbing the next hill. Batteries and many other parts of the tech are not ready for prime time yet. But this system, obviously, can be implemented today and there are no energy losses from energy conversion and storage.
Daimler Chrysler: Sustainability
Predictive Cruise Control.
One particularly intelligent means of saving fuel is currently being tested by our researchers in the USA. Back in 2002, they began taking a closer look at the potential of existing cruise control systems in Freightliner’s heavy trucks and tractor vehicles, searching for ways to combine the comfort already provided by electronic systems with fuel-saving control programs. The outcome of their efforts is “Predictive Cruise Control” (PCC), a cruise control system that not only maintains a preset speed, but also regulates the engine by assessing driving conditions ahead and adjusting speed accordingly, delivering significant fuel savings. The benefits are clear on up- and downhill routes, for example. At the beginning of an upgrade, a conventional cruise control system would try to compensate for the truck’s deceleration by boosting engine output to the maximum. Then, on the downgrade the system would have to shift down drastically to prevent the truck from rolling too fast. PCC instead makes optimum use of the truck’s kinetic energy by allowing it to build up momentum before the hill and then, at the top, gearing down even further in anticipation of the truck’s rapid acceleration as it moves downhill. The PCC computer can do all this because it has been fed the topographical data for the route and, thanks to the GPS navigation system, also knows the truck’s precise position. Initial tests have confirmed the research engineers’ estimates: Depending on the specific route, PCC can bring fuel savings of two percent or more.
Hopefully this will come to fruition. of course while you are plotting all the topographical features, why not put speed limits in the system as well. It wouldn't be too much of a reach to do the state/province level even if one didn't go to a road by road system. Many downgrades have much lower speed limits for trucks, perhaps those could be hard coded in.
Fleet Owner:maximizing MPG
“Eight or nine years ago, the thermal efficiency of a heavy-truck diesel engine was around 54%. Now, with the introduction of EGR [exhaust gas recirculation] and Caterpillar's ACERT [advanced combustion emission reduction technology] systems, engine thermal efficiency is down to 40%,” he explains. “That all translates into reduced mpg for heavy trucks.”
According to Routbort, “The main goal of the MET [MorElectric Truck] program is energy security. Today we're importing 53% of our oil; and based on current trends, we'll be importing 68% by 2025. Of the current $540-billion U.S. trade deficit, 22% is for oil expenditures alone. That's a lot of capital going overseas to pay for oil,” he says.
Of the 22-million barrels of oil consumed in the U.S. every day, two-thirds of it, or 13-million barrels a day (b/d) is used for transportation, with trucks burning 8-million b/d in their fuel tanks. DOE trend lines indicate that by 2025, transportation demand for oil will top 18-million b/d, with trucking consuming 12-million b/d.
That's why Routbort is so enthusiastic about the potential benefits of the MET project. “From a global standpoint, the technologies developed in this project can help reduce our reliance on imported oil, contribute to emissions reduction, and from a trucking perspective, position the industry to remain competitive,” he says.
Launched in 2000, the MET program represents a joint effort between DOE and private industry to reduce parasitic loads on heavy truck engines. Caterpillar provided engine technology, mechanical design, electronics, controls and overall system integration; Kenworth supplied a T-2000 Class 8 truck; Emerson offered electric motor and power electronics knowledge; and Engineered Machined Products developed electrically-driven water and oil pumps According to Routbort, the key to the program is the use of electrical power to enable a variety of truck systems to operate independently of the engine. Specifically, the heating, ventilation and air-conditioning (HVAC) system, brake air compressor, and oil and water pumps on the MET vehicle all operate on electricity. The accessories are powered by a generator inside the flywheel housing, which also serves as the starter motor, along with an auxiliary power unit (APU) and shore power plug-in capability.
Preliminary results indicate a 2% decrease in over-the-road fuel consumption for the MET test vehicle and 6% during engine idling. This means a saving of more than $2,000 annually per truck in fuel and engine maintenance costs.
So one could say, use a "smart" GPS integrated cruise control to anticipate which hills could be "coated" down, the electronic driveline disconnect kicks in at the top of the hills, and the engine cut off, while the Morelectric system keeps the power steering, cooling, HVAC, and air compressor running. Near the bottom of the hill or if the driver applies the brakes the engine is restarted and revved to the appropriate place to pull the next hill or take a downshift. There are a lot of good ideas out there, they just need to be put together into solutions for the industry and society.