Browse Topic: Trucking fleets
Volvo made several key announcements at the 2024 Advanced Clean Transportation (ACT) Expo in Las Vegas. The company also reaffirmed its goal of reaching net-zero carbon emissions with a 100% fossil-free fleet of trucks and off-highway machines by 2040. “The sustainable future is not only about electric trucks, though they do play a very important role,” said Peter Voorhoeve, president of Volvo Trucks North America. “It's about all the things that we transport. For a sustainable future, there is not one silver bullet. We will have different technologies that all enable zero-emissions trucks. This will include electric drivelines, hydrogen fuel cells, and internal combustion engines.”
As a mechanical engineering student at Carnegie Melon, Thomas Healy wondered why passenger cars were moving toward electrification, but commercial trucks were not. That curiosity has led to one of the greenest, most innovative, trucking concepts on the planet. “I learned that there had been some electric trucks made, but at that point they were built on lead acid batteries and outdated technology by today’s standards,” he said.
The base design of commercial vehicle wheel end systems has changed very little over the past 50 years. Current bearings for R-drive and trailer wheel end systems were designed between the 1920's and the 1960's and designs have essentially remained the same. Over the same period of time, considerable gains have been made in bearing design, manufacturing capabilities and materials science. These gains allow for the opportunity to significantly increase bearing load capacity and improve efficiency. Government emissions regulations and the need for fuel efficiency improvements in truck fleets are driving the opportunity for redesigned wheel end systems. The EPA and NHTSA standard requires up to 23% reduction in emissions and fuel consumption by 2017 relative to the 2010 baseline for heavy-duty tractor combinations. This paper summarizes the history of current wheel end bearing designs and the opportunity for change to lighter-weight, cooler-running and more fuel-efficient wheel bearing designs to help meet the new industry standards. Advanced design and modeling principles were applied to analyze improvements, leading to optimized designs. Physical testing validated that these new bearing designs can increase efficiency and reduce weight.
Trucking fleets are increasingly installing video event recorders in their vehicles. The video event recorder system is usually mounted near the vehicle's rear view mirror, and consists of two cameras: one looking forward and one looking towards the driver. The system also contains accelerometers that record lateral and longitudinal g-loading, and some may record vehicle speed (in mph) based on GPS positions. The unit constantly monitors vehicle acceleration and speed, and also records video. However, the recorded data is only stored when a preset acceleration threshold is met. The primary use of the system is to assist fleets with driver training and education, but the recorded data is also being used as a tool to reconstruct accidents. By integrating the accelerometer data, the vehicle speed and distance traveled during the event can be calculated. However, the calculated speeds and distances from video event recorder data may differ from reconstructions based on data taken from engine control modules (ECM's) or classic reconstruction techniques. The objective of this study was to determine the source(s) of these differences and to determine whether or not the differences could be accounted for and corrected. Results of the study indicate that the differences can be corrected by analyzing the recorded video and matching the calculated results to known vehicle speeds, i.e., when the vehicle comes to rest. In cases where the vehicle does not come to rest during the recorded event, the differences can only be corrected if the vehicle in question can be accurately modeled.
Whether large or small, a truck fleet operator has to know the locations of its vehicles in order to best manage its business. On a day to day basis loads need to be delivered or picked up from customers, and other activities such as vehicle maintenance or repairs have to be routinely accommodated. Some fleets use aftermarket electronic systems for keeping track of vehicle locations, driver hours of service and for wirelessly text messaging drivers via cellular or satellite networks. Such aftermarket systems include GPS (Global Positioning System) technology, which in part uses a network of satellites in orbit. This makes it possible for the fleet manager to remotely view the location of a vehicle and view a map of its past route. These systems can obtain data directly from vehicle sensors or from the vehicle network, and therefore report other information such as fuel economy. The fleet manager can receive alerts when high-level brake applications occur, which could be an indication of tailgating or aggressive driving behavior. Undesirable equipment issues or driver performance concerns can diminish safety and fuel efficiency, so identifying them is important. Various manufacturers provide competing systems in the North American market geared to providing information that is useful to their customers. Qualcomm Enterprise Services (Qualcomm) is one such manufacturer. Qualcomm systems on three separate highway tractors were tested in this research. The reason for doing so was to establish if Qualcomm data from an accident-involved vehicle could be useful to the collision investigation community in understanding what happened. The GPS aspect of the data was of particular interest since built-in vehicle systems can provide speed, brake and clutch data plus other information but they do not record geographical position. Independent physical evidence that helps explain the position-time history of a vehicle is extremely valuable to a motor vehicle collision investigator attempting to reconstruct a crash. It could be incorporated with other physical evidence such as vehicle damage, accident site tire marks and pavement scars to help determine how an accident occurred.
Stringent emission regulations have forced drastic technological improvements in diesel after treatment systems, particularly in reducing Particulate Matter (PM) emissions. Those improvements generally regard the use of Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and lately also the use of Selective Catalyst Reduction (SCR) systems along with improved engine control strategies for reduction of NOx emissions from these engines. Studies that have led to these technological advancements were made in controlled laboratory environment and are not representative of real world emissions from these engines or vehicles. In addition, formation and evolution of PM from these engines are extremely sensitive to overall changes in the dilution process. In light of this, the study of the exhaust plume of a heavy duty diesel vehicle operated inside a subsonic environmental wind tunnel can give us an idea of the dilution process and the representative emissions of the real world scenario. The subsonic environmental wind tunnel used for this study is capable of accommodating a full-sized heavy-duty truck and generating wind speeds in excess of 50mph. It was specifically designed and built by West Virginia University (WVU) to characterize the exhaust plume emitted of heavy duty vehicles. A 3 dimensional gantry system allows spanning the test section and sample regions in the plume with accuracy of less than 5mm. The gantry system was equipped with engine exhaust gas analyzers and Particulate Matter (PM) sizing instruments. The investigation involves three different heavy-duty Class-8 diesel vehicles equipped with after-treatment technologies, representative of legacy and modern truck fleets in the USA. The three vehicles investigated are representative of three emission regulation standards, namely a US-EPA 2007 compliant, a US-EPA 2010 compliant and a baseline vehicle without any after-treatment technologies as pre US-EPA 2007, respectively. The testing procedure includes three different vehicle speeds: idling, 20mph, and 35mph. The vehicles were tested on WVU's medium-duty chassis dynamometer, with the load applied to the truck reflecting the road load equation at the respective vehicle test speed. Wind tunnel wind speed and vehicle speed were maintained in close match during the entire test. Results show that, the cross-sectional plume area increases with increase in distance away from tailpipe. Also indicating the cooling and dilution of the exhaust begins at close proximity to the tailpipe. The rate of cooling and dilution are greatest in early stages of the dilution process for the areas with high turbulence intensity, where strong mixing phenomena occurs. On the other hand, the core of plume observes a slower cooling and dilution rate. This difference is reflected in the PM formation and evolution of these two distinct regions, as shown by the particle size distributions and number concentrations.
Accurately predicting the fuel savings that can be achieved with the implementation of various technologies developed for fuel efficiency can be very challenging, particularly when considering combinations of technologies. Differences in the usage of highway vehicles can strongly influence the benefits realized with any given technology, which makes generalizations about fuel savings inappropriate for different vehicle applications. A model has been developed to estimate the potential for reducing fuel consumption when advanced efficiency technologies, or combinations of these technologies, are employed on highway vehicles, particularly medium- and heavy-duty trucks. The approach is based on a tractive energy analysis applied to drive cycles representative of the vehicle usage, and the analysis specifically accounts for individual energy loss factors that characterize the technologies of interest. This tractive energy evaluation is demonstrated by analyzing measured drive cycles from a long-haul trucking fleet and the results of an assessment of the fuel savings potential for combinations of technologies are presented. The results of this research will enable more reliable estimates of the fuel savings benefits that can be realized with particular technologies and technology combinations for individual trucking applications so that decision makers can make informed investment decisions for the implementation of advanced efficiency technologies.
About 360,000 commercial trucks are involved in traffic accidents in the United States per year. Approximately 20,000 truck drivers are injured in those crashes. This study examines traffic crashes of the commercial truck fleet for model years 2000 to 2008 contained in the Trucks Involved in Fatal Accidents (TIFA) and General Estimates System (GES) databases. Specifically, driver injuries, using the KABCO scale (injury severity), were analyzed to determine the association with crash type as well as with the truck configuration. A crash typology was developed to identify crash types, including the type of other vehicle or object struck as well as the impact point on the truck, associated with the most serious injuries. This research focuses on the frequency of commercial vehicle accidents and driver injury levels rather than the cause of the vehicle crash. Based on these findings, example cases from LTCCS were selected. These examples typify the most frequent crashes and injuries.
A multi-year technology validation program was completed in 2001 to evaluate ultra-low sulfur diesel fuels and passive diesel particle filters (DPF) in several different diesel fleets operating in Southern California. The fuels used throughout the validation program were diesel fuels with less than 15-ppm sulfur content. Trucks and buses were retrofitted with two types of passive DPFs. Two rounds of emissions testing were performed to determine if there was any degradation in the emissions reduction. The results demonstrated robust emissions performance for each of the DPF technologies over a one-year period. Detailed descriptions of the overall program and results have been described in previous SAE publications [2, 3, 4, 5]. In 2002, a third round of emission testing was performed by NREL on a small subset of vehicles in the Ralphs Grocery Truck fleet that demonstrated continued robust emissions performance after two years of operation and over 220,000 miles. As of 2003, there are still questions about the durability of the passive DPF technology. Will the technology maintain emissions reduction performance over a long period of operation? Will it meet the durability criteria expected by the heavy-duty diesel community? A fourth round emissions evaluation of a subset of the Ralphs Grocery Truck fleet from the original ARCO EC-Diesel™ Technology Validation Program [2] was performed and an assessment of the technology will be presented in this paper. Emissions testing was performed during the summer of 2003 to provide data covering 3-½ years of operation and 340, 000 miles. The evaluation will examine some of the key parameters that allows for the successful implementation of the passive DPF in this heavy-duty application. This will include examining the engine exhaust gas temperatures, the backpressures created by the DPF and NOx/PM ratios provided by the engine application. The results will show that with a NOx/PM ratio better than 20:1 and exhaust gas temperatures above 250°C, the technology will provide robust long-term performance with emission reductions of 99% PM, 85% HC, and 65% CO in a heavy-duty application with some significant variability associated with the CO and HC measurements.
Researchers at ExxonMobil have developed an advanced lubricant for heavy-duty diesel engines. Operators of heavy-duty diesel engines continue to express interest in extending the distance traveled and time between engine service intervals to reduce vehicle downtime and increase the overall profit contribution of each piece of equipment. Extending oil-drain intervals also lowers purchasing costs for engine oil and filters, labor costs to conduct scheduled maintenance, and disposal costs for used oil and filters. Oil-drain interval extension must be carefully monitored and a suitable high-performance lubricant used to ensure that engine durability and reliability are not diminished, thus negating the monetary benefits of extending the oil-drain interval. According to ExxonMobil, the choice of an appropriate extended-service lubricant is particularly critical for modern low-emissions diesel engines, which expose the oil to a more severe operating environment.
Reports of disabling diesel engine seal failures which accompanied the introduction of low sulfur diesel fuel in October '93 prompted an in-depth survey of diesel fuel chemical and physical properties. The purpose of the survey was to anticipate other possible problems which might arise with the newly introduced low sulfur fuels. The survey will produce a database containing over 1000 number 2 diesel fuels from various parts of the US. About 75% of the samples tested were on-highway low sulfur diesel fuels. Samples analyzed were from the D-A Lubricant Company, Cummins customers failures (truck fleets of various sizes), and a number of retail fueling stations. Properties under investigation are % Sulfur, Cloud/Pour Points, Viscosity, API Gravity, TAN/TBN, Boiling Range, Aromatics content, Heat Content, Lubricity, and Peroxide number. While each sample was not tested for all the properties listed, an adequate number of samples were tested to give a clear picture of diesel fuel properties for samples collected over a 5 month period. Diesel fuel speciation was helpful in providing an understanding of many of the differences noted for low sulfur fuels.
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