Truck operations of all sizes must continue their quest for more efficient drivetrains that will help reduce total cost of ownership, and it’s easy to see how vehicle owners who achieve more fuel efficiency through engine down-speeding and lighter weight vehicles will be more strongly positioned to grow and to delight their shippers.
According to Steve Slesinski, director of global product planning for Dana Commercial Vehicle Driveline Technologies, fleets are active in deploying truck equipment strategies that reduce maintenance and total ownership costs. Technologies that boost vehicle efficiency or increase payload are welcome so long as productivity and reliability are not compromised. And while these trends are spawned by recent greenhouse gas legislation and new fuel efficiency standards and targets, the durability of a fleet’s vehicles remains key to the industry.
“Our job as drivetrain engineers and manufacturers is to think about reducing the total cost of fleet ownership, including the long-term vehicle residual value. Not only do we support the primary fleet customer, we also need to anticipate how we might maximize the appeal of the components and the entire system to second and third owners,” Slesinski said.
Powertrain efficiency boosts fuel economy, lowers costs
Slesinski feels that down-speeding is the name of the game for boosting efficiency, because cruising at a lower engine speed uses less fuel. However, axle and driveshaft components have to be extremely robust to sustain the high torque loads associated with down-speeding the engine, especially at startup and in the lower ratios of the transmission. For example, a decrease in the rear axle ratio from 3.55:1 to 2.26:1 produces a 57 percent increase in torque.
Advancements in driveline equipment, such as the Spicer AdvanTEK 40 tandem axle and the SPL 350 driveshaft offered by Dana, enable fleets to reduce engine speed at cruise by up to 200 RPM while maintaining long-term reliability.
Rolled out earlier this year, the Spicer AdvanTEK 40 6×4 tandem axle offers a full range of 13 ratios, including the industry’s fastest axle ratio of 2.26:1, while weighing up to 42 lbs. less than competitive 40,000-lb. tandem axles.
Dana also offers SPL 350 and SPL 250 driveshafts designed to maximize the benefits of engine down-speeding. “We engineered our axle and driveshaft package with innovations that include more reliable gearing systems, high-strength steel shafts, and larger bearings and u-joints, and they are performing exceptionally well,” Slesinski said.
He cited several other examples of components that offer improved performance and efficiency:
- The new Spicer E-Series steering axle weighs up to up to 35 lbs. less than previous iterations and features a steel-forged beam design to cut weight and improve “torsional stiffness” for handling beefed-up braking power. These revamped steering axles are targeted for on-highway, city delivery, and bus chassis applications with gross axle weight ratings from 10,000 to 13,200 lbs.
- Dana also recently introduced a new Spicer D-Series steer axle for GAWRs from 10,000 to 14,600 lbs. that features an integrated air disc brake or “IADB” knuckle that allows fleets to specify air disc brakes without a net increase in weight over most S-cam drum brake axle systems. Facilitating air disc brakes on the steer axle helps fleets meet reduced stopping distance requirements while offering better performance and reduced maintenance.
- Finally, Dana’s new “all-makes” line of service parts supplies complete coverage for Spicer-branded steer axles, including knuckles, steer arms, crosslink assemblies, beams, and whole axle assemblies. It also includes draglinks, tie rod ends, and king pin kits for all makes and models of heavy-duty vehicles.
- Achieving lower maintenance requirements requires the extension of service intervals, and most all of Dana’s components meet that objective, according to Slesinski.
Lighter weight products make a difference
Component weight is critically important, especially as tractors have gotten progressively heavier. Exhaust aftertreatment systems alone add as much as 400 lbs. per vehicle. According to TMC, a 1,000 lb. weight savings improves fuel economy by about 0.6%, leading to significant dollar savings.
“Lighter weight components will ultimately save fuel and improve payload, but they also need to be designed to meet application requirements for durability and reliability,” Slesinski said.
Fleet managers are looking to trim weight out of numerous components, and some are moving toward the 6×2 axle configuration to meet this goal. Last year, Dana introduced the Spicer EconoTrek tandem axle for these fleets. “Our mission is to reduce the total cost of ownership for the truck owner, and it is important to consider a fleet’s duty cycle when selecting vehicle specifications,” said Slesinski.
For the fleets looking at 6×2 configurations as a way to reduce weight and increase payloads, it is important to consider traction requirements and resale values. The ideal candidates for a 6×2 are bulk haulers and applications in warmer climates with fewer variations in road conditions.
Reducing weight in the driveshaft was another target of Dana. Two years ago, the company introduced the Spicer Diamond Series, a line of lightweight driveshafts that successfully pairs steel end fittings with a single-piece, high-strength aluminum tube. These driveshafts are up to 100 lbs. lighter than a two-piece steel driveshaft, depending on the vehicle’s wheelbase configuration.
Two-way communication with fleets
“Listening to fleets of all sizes never goes out of style, and this channel of communication is vital in the development of our current and future products and systems,” he said. “Our field managers’ focused insights are more valuable than ever.”
Dana’s North American commercial-vehicle sales and service organization of knowledgeable professionals includes dedicated applications and engineering contacts to serve thousands of fleets and dealers.
“Customer intimacy enables great product development,” summarized Slesinski, who knows the field force’s key role in gauging the requirements of the axles and driveshafts required by the market today.
The success of this approach can be seen in the development of the new SPL 350 driveshaft. Dana experts have been mapping trends in engine down-speeding, axle ratios, and powertrain torque for many years. Leveraging the company’s understanding of regulatory timing, the efficiency goals of OEM and fleet customers, and collaboration with engine and transmission manufacturers, Dana was able to develop and deliver the SPL 350 driveshaft at a time when the market demands a driveshaft with exceptional torque capacity.
Other fleet and dealer tools beyond field interaction include a host of web tools to support customers, such as programs to streamline the spec’ing process, the “Dispatched” e-newsletter, the Dana Mobility Matters blog, the Dana Extras app for mobile devices to assist in spec’ing, training and service needs, individual field rep micro-sites, a robust leads management program, and other electronic touch points.
So what does Dana see on the drivetrain design horizon:
- Sensors mounted to the axle to more closely monitor operation;
- Tire pressure monitoring and inflation technology for power units;
- 500,000 mile lube drain intervals with extra fuel-efficient synthetic axle lube that supplies the best protection for seals and bearings and contributes to even greater fuel efficiency;
- Products with higher power densities that reduce weight by using materials currently available and under development;
- Increased collaboration with OEs to optimize the entire system in a way that goes far beyond a myopic focus on individual components.
“And don’t overlook that other key component of the drivetrain’s efficiency – the professional driver who starts, drives and stops the vehicles. An operator has to start the vehicle and control its drivetrain operation. If the driver is erratic, shifts too much, over-revs the engine or allows it idle too long, fuel efficiency degrades instantly.”
Taken as a whole, the components in a drivetrain system impact the vehicle’s fuel efficiency by as much as 4 percent on the interstate and up to 6 percent in urban applications. “Our charter is clear: we must continue to anticipate market needs, develop products ahead of demand, and leverage our abilities to innovate and collaborate — all toward the goal of delivering the performance that fleets expect,” Slesinski concluded.