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Technical Paper

Trailer Aerodynamic Technologies Wind Tunnel Testing Compared to Track Test Results

The performance of several aerodynamic technologies, such as trailer skirts, vortex generators, and aerodynamic van trailer obtained from model wind tunnel testing were compared with track test results. Wind tunnel tests were conducted on 1/8, 1/15 or 1/24 scale models of a tractor in combination with 53-foot semi-trailer. The tests consisted of two phases: setting the initial baseline, and component testing of various configurations. The SAE Fuel Consumption Test Procedures Type II and Type III were used for track test evaluations. The differences between the track and wind tunnel test results are in some cases explained directly by the some differences between the real scale device and the model. In other situations, the variability and realism of tract testing explain the differences. The wind tunnel results were closer to the track test results for 1/8 scale models than for smaller scale models.
Technical Paper

Track-test Evaluation of Aerodynamic Drag Reducing Measures for Class 8 Tractor-Trailers

Air resistance, after gross vehicle weight, is the largest factor responsible for vehicle energy loss and has an important influence on fuel consumption. The magnitude of aerodynamic drag is affected by the vehicle's shape, frontal area, and travel speed. This study aimed to evaluate several aerodynamic drag reduction measures applicable to class 8 tractor-trailer combinations. The tested aerodynamic devices included trailer aft body rear deflectors (boat tails), trailer skirts, gap deflectors, fuel tank fairings and truck rear-axle fenders. It also assessed the aerodynamic influence of opened doors on an empty wood chip van trailer on the fuel consumption of the tractor-trailer combination. The tests were conducted according to SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II.
Journal Article

The Impact of Lift Axles on Fuel Economy and GHG Emissions Reduction

Using lift axles enables fleet to increase the load capacity of a vehicle, eliminating the need for multiple trips, thus reducing operational costs. In a project to assess the potential of reducing fuel consumption and greenhouse gas (GHG) emissions by lifting axles on unloaded semi-trailers, lift axle regulations in various jurisdictions and the studies that led to these regulations were analyzed. The SAE Fuel Consumption Test Procedures Type II (J1321) was used for fuel consumption track test evaluations. The tests were conducted on unloaded two-axle van semi-trailers, four-axle van semitrailers, and B-trains, and resulted in fuel savings of 1.3% to 4.8%, depending on vehicle configuration and the number of axles lifted during the test.
Journal Article

The Impact of Design, Position and Combination of Aerodynamic Devices on Drag and Fuel Consumption

The performance of several aerodynamic technologies and approaches, such as trailer skirts, trailer boat tails, gap reduction, was evaluated using track testing, model wind tunnel testing, and CFD simulation, in order to assess the influence of the design, position and combination of various aerodynamic devices. The track test procedure followed the SAE J1321 SAE Fuel Consumption Test Procedure - Type II. Scale model wind tunnel tests were conducted to have direct performance comparisons among several possible configurations. The wind tunnel tests were conducted on a 1/8 scale model of a tractor in combination with a 53-foot semi-trailer. Among others, the wind tunnel tests and CFD simulations confirmed the influences of trailer skirts' length observed during the track tests and that the wider skirt closer to the ground offer better results. The differences in the shape, dimensions and position of rear deflectors and trailer skirts on the trailer are reflected in the test results.
Technical Paper

Performance Evaluation of Heavy-Duty Vehicles Equipped with Automatic Transmissions and Powertrain Adaptive Systems in Forestry Transportation

The purpose of this study was to evaluate automatic transmissions in a forestry context by comparing their performance with that of standard manual transmissions, and assessing the possibility of improving fuel efficiency by adapting the engine and automatic transmission performances to the vehicle's load. Long-haul test results showed that during the test day, the degradation in driver performance with the manual transmission truck translated into a 2.9% relative increase in fuel consumption when compared with the automatic transmission truck. The fleet data assessment indicated no obvious difference in fuel consumption between the performance of automatic transmissions and manual transmissions. One system for adapting engine performance to vehicle load uses an onboard weigh scale to determine the load status of the vehicle.
Technical Paper

Influences on Energy Savings of Heavy Trucks Using Cooperative Adaptive Cruise Control

An integrated adaptive cruise control (ACC) and cooperative ACC (CACC) was implemented and tested on three heavy-duty tractor-trailer trucks on a closed test track. The first truck was always in ACC mode, and the followers were in CACC mode using wireless vehicle-vehicle communication to augment their radar sensor data to enable safe and accurate vehicle following at short gaps. The fuel consumption for each truck in the CACC string was measured using the SAE J1321 procedure while travelling at 65 mph and loaded to a gross weight of 65,000 lb, demonstrating the effects of: inter-vehicle gaps (ranging from 3.0 s or 87 m to 0.14 s or 4 m, covering a much wider range than previously reported tests), cut-in and cut-out maneuvers by other vehicles, speed variations, the use of mismatched vehicles (standard trailers mixed with aerodynamic trailers with boat tails and side skirts), and the presence of a passenger vehicle ahead of the platoon.
Journal Article

Fuel Consumption Track Tests for Tractor-Trailer Fuel Saving Technologies

The objective of the project was to conduct controlled test-track studies of solutions for achieving higher fuel efficiency and lower greenhouse gas emissions in the trucking industry. Using vehicles from five Canadian fleets, technologies from 12 suppliers were chosen for testing, including aerodynamic devices and low rolling resistance tires. The participating fleets also decided to conduct tests for evaluating the impact on fuel consumption of vehicle speed, close-following between vehicles, and lifting trailer axles on unloaded B-trains. Other tests targeted comparisons between trans-container road-trains and van semi-trailers road-trains, between curtain-sided semi-trailers, trans-containers and van semi-trailers, and between tractors pulling logging semi-trailers loaded with tree-length wood and short wood. The impact of a heavy-duty bumper on fuel consumption and the influence of B5 biodiesel blend on fuel consumption were also assessed.
Technical Paper

Fuel Consumption Tests for Evaluating the Accuracy and Precision of Truck Engine Electronic Control Modules to Capture Fuel Data

Many trucking fleets and organizations are extensively using truck onboard computers (OBC) to gather fuel consumption data from truck engines' Electronic Control Modules (ECM). This study aimed to assess the accuracy and the precision of truck engine control module concerning the fuel consumption data. The testing methodology evaluated the fuel consumption data provided by the ECM using test track and road fuel consumption tests, short-term operational observation, long-term operational observation and engine dynamometer tests. ECM data were retrieved using either onboard computers (OBC) or engine scan tools. Test track and road tests were mainly intended to evaluate the precision of ECM data for short distances, between 60 and 100 km. More than 220 test runs totalizing 22,000 km were conducted using 23 test vehicles.
Journal Article

Evaluation of the Influence of Stakes on Drag and Fuel Consumption for a Tractor-Logging Trailer Combination

The main objective of this study is to reduce the aerodynamic drag of tractor-trailer combinations used in the forest industry. In most cases, logging trucks on their return trips are usually travelling in unloaded conditions with upright stakes, which add drag. CFD and wind tunnel testing suggested a drag reduction of up to 35% with no upright stakes, which corresponds to 17% in fuel savings in unloaded conditions. One of the proposed fuel reduction concepts was therefore to have foldable stakes so that the stakes could fold down into a horizontal position while travelling in unloaded conditions. Fuel savings of 15% for a vehicle with stakes in the horizontal position were confirmed with track testing when compared to the fuel consumption of a vehicle with stakes in the vertical position. The coastdown test indicated 28% reduction in drag. The difference in drag reduction between the coastdown test and initial simulation was due to stake size and profile.
Technical Paper

Evaluation of Tractor-Trailer Rolling Resistance Reducing Measures

This study aimed to evaluate several rolling resistance reduction measures applicable to class 8 tractor-trailer combinations. Two methods have been employed: fuel consumption tests according to the SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II, and long-term operational observations using control and test vehicles monitored throughout baseline and test periods. One way to reduce the rolling resistance is to use wide-base tires: two different Type II fuel consumption tests revealed a more than 9 % improvement in fuel economy for a tractor-trailer combination equipped with wide-base tires. Long-term operational observation assessed the use of single wide-base tires on two 8-axle B-train tractor-trailer combinations. The results showed an average 5.11% fuel improvement and an average 4.37% energy intensity improvement. Other tests compared single-wide base tires with different tread patterns and tire compounds.
Technical Paper

Evaluation of Engine Programming to Reduce Fuel Consumption

The goal of this study was to evaluate the potential for reducing fuel consumption of heavy-duty vehicles by modifying their engine power ratings through programming of their engine electronic control units. This paper summarizes the activities, observations, and results obtained from tests conducted on a test track to compare default settings with those optimized for potential economic gains and improved performance. Tests for long-distance and regional transport operations were conducted at constant speed. Results from these tests showed considerable fuel savings, of approximately 7%, when the engine power rating was reduced from 450 hp to 400 hp and speed from 105 km/h to 98 km/h. In these tests, the dynamic performance of the vehicles was not affected by the reduction in power.
Technical Paper

Evaluation of Energy Efficiency Performance of Refrigerated and Heated Van Semitrailers

The objective of this project was to provide pertinent information on the performance of refrigeration and heating transportation units to help fleets make decisions that will improve efficiency and increase productivity. To achieve this objective, tests were designed to measure the performance of selected refrigeration and heating units, mounted on refrigerated and heated van semitrailers. Cooling and freezing tests were carried out in summer conditions while heating tests were carried out in winter conditions, for various temperature settings. Two fundamental approaches were considered: the design of the refrigerated or heated trailer and the temperature setting of the refrigeration or heating unit. For cooling and freezing tests, the fuel consumption comparison between similar trailer models of different ages showed that newer units performed better than older ones.
Technical Paper

Evaluation of Class 7 Diesel-Electric Hybrid Trucks

The objectives of this project were to evaluate the reduction in fuel consumption and greenhouse gas (GHG) emissions made possible by hybrid technology, and to identify good driving habits with this type of vehicle. Two diesel-electric hybrid pick-up and delivery trucks and one diesel-electric hybrid utility vehicle equipped with an electric driven PTO (power take-off) system were included in the project. The first phase was the evaluation in actual operating conditions. Onboard computers were installed in the vehicles to record parameters that make it possible to determine driving habits. Based on operational data, specific duty cycles were built and track tests were conducted to measure the fuel consumption on these duty cycles. It was therefore possible to compare the hybrid trucks with other diesel trucks featuring similar characteristics. The delivery hybrid trucks showed up to 34% fuel savings during the track tests.
Technical Paper

Development of a Fuel Consumption Test Procedure for Representative Urban Duty Cycles

This project's objective was the development of an on-road vehicle fuel consumption test procedure for representative stop-and-go urban duty cycles. The scope of the project included a review of existing stop-and-go urban duty cycles, the development of a track testing methodology for measuring the fuel consumption on stop-and-go urban duty cycles, and testing with a view to the validation of the methodology. Literature review analyzed several transport activities to determine specific stop-and-go urban duty cycles, such as pick-up and delivery operations, refuse collection, bus transport, and utility and service operation. It was found that driving cycles should be easy enough to recreate and replicate on the test track and should be representative of application driving patterns. The cycles should be adapted for fuel economy testing, and geometric cycles are easier to follow than the cycles based on actual drive traces.
Journal Article

Development of a Fuel Consumption Test Procedure for Refrigeration Units

This project's objective was the development of a test procedure to evaluate the impact of the refrigerated van box on the fuel consumption of the refrigeration unit. The scope of the project included a review of the test procedures, the development of a testing methodology for measuring the fuel consumption of the refrigeration unit on a specific duty cycle, and testing with a view to validating the methodology. Road and track tests are subject to variations in conditions, and controlling or accounting for these variables as much as possible is an important part of ensuring accurate results. However, when testing a refrigerated van on the track or on the road, it is very difficult to eliminate variable external influences and to isolate the particular influence of the refrigerated van on the refrigeration unit's fuel consumption. For this reason, tests were conducted in an environmental chamber in controlled temperature and humidity conditions.
Journal Article

Comparison of Fuel Efficiency and Traction Performances of 6 × 4 and 6 × 2 Class 8 Tractors

The objective of this project was to compare the fuel consumption and traction performances of 6 × 2 and 6 × 4 Class 8 tractors. Two approaches have been considered: evaluation of 6 × 2 tractors, modified from 6 × 4 tractors, and evaluation of OEM 6 × 2 tractors. Compared to the 6 × 4 tractors, which are equipped with a rear tandem with both drive axles, the 6 × 2 tractors have a rear tandem axle with one drive axle, and one non-drive axle, also called dead axle. The 6 × 2 tractor configurations are available from the majority of Class 8 tractor manufacturers. The SAE Fuel Consumption Test Procedures Type II (J1321) and Type III (J1526) were used for fuel consumption track test evaluations. Traction performances were assessed using pull sled tests to compare pulling distance, maximum speed, and acceleration when pulling the same set sled on similar surface.
Technical Paper

Comparison of Dynamic Performance and Fuel Consumption of Direct-drive and Overdrive Transmission Tractors

The main objective of this project was to compare the fuel consumption and dynamic performances of direct-drive and overdrive transmission tractors. Fuel consumption was evaluated at constant high speed and on various road profiles, while the dynamic performance was assessed on various road profiles only. The SAE Fuel Consumption Test Procedure (J1526) was used for constant high speed fuel consumption track test evaluations. The direct-drive transmission tractor consumed less than the overdrive transmission tractor, even though it was heavier. The testing on various road profiles was conducted using a towing dynamometer, for comparing the dynamic capability of the tractors when simulating the same towing load on two hilly road profiles: the Townes Pass path (in the Rocky Mountains) and the Saguenay path (in the Saguenay region of Quebec). Each tractor was to haul the set load along the given path while trying to attain 90 km/h speed.