With continuous development, the latest technologies for heavy duty vehicle axles are focused on maintenance and performance improvement. Recently, Fleet equipment spoke to several heavy-duty axle manufacturers about design initiatives, new axle specifications and the advent of electronics. Participated in the discussion:
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• Steve Mastroianni, Senior Director of Product Planning, Dana
• John Bennett, Vice President and Chief Technology Officer, Meritor
• Sean Whitfield, Marketing Director, Hendrickson
What are the latest developments in axles for commercial vehicles and what needs or trends have these changes been designed for?
Mastroianni: In order to meet Phase 2 greenhouse gas (GHG) regulations, developments in steering and drive axles have focused on weight reduction, speed reduction and torque support capabilities. To support engine speed reduction for inline transport applications, drive axles are designed with faster ratios that can handle higher axle input torques resulting from lower engine speed. at highway speed. Additionally, with increased use of 6 × 2 configurations, single drive axles can be designed to accommodate super-fast ratios and allow engine speed reduction.
Additionally, as the industry continues to move towards electrification, innovation continues for drive axles that will be successfully mated to electric powertrains. This includes designing to regenerative torque load requirements as well as integrating the correct axle for electrified applications.
Bennett: Current developments for drive axles have focused on reducing greenhouse gas (GHG) emissions by reducing efficiency losses through high efficiency gears and bearings. Additionally, faster gears allow diesel engines to run at slower speeds. On the steer axle side, the focus has been on weight reduction by integrating the wheel side of the steering arms, link arms, axles and torsion plates.
Looking to the future, with a lot of activity going on for electric vehicle technologies, there is an opportunity for the integration of the electric motor and transmission into the axle itself. This will result in very compact and high power density systems which will allow more batteries to be packed in the vehicle to help increase the operating range.
Whitfield: The market continues to demand lightweight products that offer improved performance, whether for ease of maintenance, better handling or better handling. For example, steered axle systems have optimized kinematics with minimized bump and roll steering. This results in a decrease in the transmission of feedback from the road to the driver, whether through the seat or the steering wheel, which can help reduce driver fatigue.
With the evolution of integrated powertrain offerings, how have axle designs and specifications changed?
Bennett: It comes down to developing faster and lower digital ratios and changing the gear designs in the axles so that the motors can run at slower speeds. Typically, the focus is on improving the ability of gear trains, bearings, and drivetrains to accommodate shifting. This translates into a greater benefit to the overall performance of the system.
Mastroianni: Integration includes axles synchronized with a vehicle platform and powertrain technologies. Additionally, axles offered with customization provide the design to meet today’s wide application requirements. Additionally, understanding the relationship between axle and driveshaft in today’s low speed transmissions is essential. Coupling the right driveshaft with the right drive axle to mitigate issues like noise, vibration, and harshness is crucial when it comes to the various vehicle harmonics produced when an engine is running at a lower speed.
As automakers increasingly integrate electronics, what features, capabilities and benefits will these systems bring to axle performance and maintenance?
Whitfield: The 6 × 2 lift front axles designed to improve efficiency can use systems that sense fifth wheel loads and automatically raise the front tandem axle when a deployment threshold, determined by tractor configuration, is reached.
Bennett: Industry is starting to look at what kind of telematics information and sensors it can use to further reduce maintenance costs and be more proactive in service. Emphasis is placed on the integration of sensors into vehicles. For axles, telematics can monitor parameters such as temperature, vibration and even weight. The integration of weight or load sensors can tell the driver the exact load on each axle so that fleets can be assured that they are operating safely within legal limits. Likewise, via telematics, we can monitor vibrations and provide the fleet manager with an indication that a bearing will need to be replaced soon before it causes further damage resulting in higher service bills.
Mastroianni: Along with the axle electrification initiatives, there is also innovation around preventive axle maintenance sensors. These health monitoring technologies could potentially focus on maintenance issues like lubricants, steered axle alignment, and overall structural health, to name a few.