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This paper summarizes the techniques and guidelines which were used to reduce the driver perceived noise level of a 145-210 HP series of agricultural tractors. Graphs of case study test results and comments on subjective noise quality are provided to guide the acoustic novice through the complexities of the vehicle sound environment in a methodical problem solving format.

Contact the appropriate representative of the 2023 Noise and Vibration Conference and Exhibition.

Health related problems in over populated areas are a major concern and as such, there are specific legislations for noise generated by transport vehicles. In diesel powered commercial vehicles, the source for noise are mainly related to rolling, transmission, aerodynamics and engine. Considering internal combustion engine, three factors can be highlighted as major noise source: combustion, mechanical and tailpipe. The tailpipe noise is considered as the noise radiated from the open terminations of intake and exhaust systems, caused by both pressure pulses propagating to the open ends of the duct systems, and by vortex shedding as the burst leaves the tailpipe (flow generated noise). In order to reduce noise generated by vehicles, it is important to investigate the gas interactions and what can be improved in exhaust line design during the product development phase.

The demand of game-changing technologies to improve efficiency and abate emissions of heavy-duty trucks and off-road vehicles promoted the development of novel engine concepts. The Recuperated Split-Cycle (R-SC) engine allows to recover the exhaust gases energy into the air intake by separating the compression and combustion stages into two different but connected cylinders: the compressor and expander, respectively. The result is a potential increase of the engine thermal efficiency. Accordingly, the 3D-computational fluid dynamics (CFD) modelling of the gas exchange process and the combustion evolution inside the expander becomes essential to control and optimize the R-SC engine concept. This work aims to address the most challenging numerical aspects encountered in a 3D numerical simulation of an R-SC engine.

The new 5480 Reach Truck, designed at Dynamic Industries, introduces a movable frame between the main frame and the telescopic boom. The use of this movable frame allows the usually fixed boom pivot to be elevated for greater lifting heights with smaller boom sections. By combining the motions of the boom and the movable frame, horizontal motion at the boom tip is possible without moving the truck. With the movable frame, the total machine height and length can be reduced for a given lifting goal. Another advantage of the movable frame is the ability to reach further below grade than is now possible in the industry. The 5480 Reach Truck has a maximum lift of 54 feet (16.5 meters) and can reach 24 feet (7.3 meters) below-grade.

The LTL-900 Transi-Lift crane features front and rear crawler-mounted load platforms connected with a hoist-supporting five foot diameter pipe section. The pin-together main boom is available in lengths up to 400 feet and completely disassembles for ease of transport to and from the jobsite. The crane requires three operators and can hoist, boom, swing and travel simultaneously with maximum loads. Upending, moving and setting large refinery vessels is facilitated by the mobility of the crawler-supported crane on unprepared surfaces. Up to 1000 tons of 36 ton concrete beams or equivalent are required as counterweight to develop the ANSI B30.5 approved capacities.

A unique shuttle bus is being constructed by Minicars, Inc., and Walter Vetter Karosserie-werk for Denver’s Transitway/Mall. The bus is designed for frequent stop, low speed service in a downtown pedestrian environment. It features a very low floor and multiple wide doors for rapid passenger boarding and deboarding. Two versions will be supplied for comparative evalation, a low noise diesel configuration and a battery-electric configuration. Either version can subsequently be converted to the alternative propulsion system.

The paper addresses some aspects of an ongoing research on a commercial compact excavator. The interest is focused on the analysis and modelling of the whole hydraulic circuit that, beside a load sensing variable displacement pump, features a stack of nine proportional directional control valves modules of which seven are of the load sensing type. Loads being sensed are the boom swing, boom, stick and bucket, right and left track motors and work tools; instead, the blade and the turret swing users do not contribute to the load sensing signal. Of specific interest are the peculiarities that were observed in the stack. In fact, to develop an accurate AMESim modelling, the stack was dismantled and all modules analysed and represented in a CAD environment as 3D parts. The load sensing flow generation unit was replaced on the vehicle by another one whose analysis and modelling have been developed using available design and experimental data.

To meet future needs for heavy truck cooling, a novel high performance radial compact cooling system (CCS) was developed. Measurements with a prototype system were conducted in a component wind tunnel and with truck-installed systems in a climatic vehicular wind tunnel. The CSS is compared to conventional axial and side-by-side systems. In comparison with a conventional axial system, the performance per unit volume of the CCS is 42% higher, the noise level is about 6 dB lower and the power consumption of the radial fan is 70% of the axial fan leading to significant savings in fuel consumption.

Despite the general similarity of U.S. and European heavy trucks, there are differences in design properties that affect braking and turning performance. A European tractor-semitrailer was studied for the purpose of comparing its properties to those of U.S. vehicles and assessing the comparative performance. Mass, suspension, and braking system properties of the European tractor and semitrailer were measured in the laboratory and on the proving ground. Turning and braking performance qualities were evaluated by computer simulation and by experimental tests. In turning performance the European combination had a 9 percent advantage in rollover threshold, compared to a generic U.S. vehicle with properties that were in the midrange of U.S. design practice. Higher suspension roll stiffness and higher chassis weight on the European tractor and semitrailer accounted for the higher threshold.

Collision warning systems (CWS) are a relatively new technology to reduce or mitigate motor vehicle rear-end and side impact collisions. This study compared available police-reported crash experiences of 6,143 CWS-equipped heavy trucks with the experiences of 383,058 heavy trucks without CWS. Data were from the Motor Carrier Management Information System (2000-2002). Results suggest that CWS-equipped trucks had a significantly lower proportion of crashes involving other moving vehicles and a significantly lower proportion of multiple vehicle crashes compared to trucks without CWS, (40% vs. 49%, p<0.0001; 62% vs. 67%, p<0.004 respectively). These changes are the first crash-data based evidence that supports the design effect of CWS. However, more studies are needed to determine the specific impacts of CWS on heavy truck crashes.

Comparison studies have been conducted on a 1:16th scale model and a full scale tractor trailer of a variety of sealed aft cavity devices as a means to develop or enhance commercial drag reduction technology for class 8 vehicles. Various base cavity geometries with pressure taps were created for the scale model. The studies confirmed that length has an important effect on performance. The interaction of the boat-tailed aft cavity with other drag reduction devices, specifically side skirts, was investigated with results showing no discernable drag performance interaction between them. Overall, the experiments show that a boat-tailed aft cavity can reduce the drag up to 13%. Full-scale tests of a commercially derived product based on these scale tests were also completed using SAE Type II testing procedures. Full-scale tests indicated a fuel savings of over 6.5%.

A computer simulation was developed to investigate the effect of wind on test track estimation of heavy truck fuel efficiency. Monte Carlo simulations were run for various wind conditions, both with and without gusts, and for two different vehicle aerodynamic configurations. The vehicle configurations chosen for this study are representative of typical Class 8 tractor trailers and use wind tunnel measured drag polars for performance computations. The baseline (control) case is representative of a modern streamlined tractor and conventional trailer. The comparison (test) case is the baseline case with the addition of a trailer drag reduction device (trailer skirt). The integrated drag coefficient, overall required power, total fuel consumption, and average rate of fuel consumption were calculated for a heavy truck on an oval test track to show the effect of wind on test results.

A class of heavy truck vehicles, characterized primarily by high centers of gravity, was studied using analysis and computer simulation to identify and understand the relationship between directional and roll stability of such vehicles during steady turning maneuvers. Findings of the computer-based study suggest: (1) directional instability (yaw divergence) is possible for such vehicles during steady turning while operating at elevated speeds on horizontal road surfaces, (2) yaw divergence will lead to rollover in the absence of corrective steering action and/or reduced speed, and (3) the primary mechanism responsible for precipitating yaw divergent behavior in such vehicles is the nonlinear sensitivity of truck tire cornering stiffness to vertical load acting in combination with typical heavy truck fore/aft roll stiffness distributions. In addition, the influences of roadway superelevation and driver steering control as contributors to vehicle stabilization are examined and discussed.

A distributed sensor is created to sense the rate of change in deflection of beam-like structures such as crane booms. This sensor will be useful in electrohydraulic compensation of boom deflections. The sensor is made of an array of strain-sensitive segments such as strain gages or piezoelectric film. In this example, segments of piezoelectric film convert strains on the surface of a vibrating beam into electrical outputs. These outputs are connected to low impedance signal conditioners. The output of the signal conditioners are then interpolated with a weighting vector that incorporates Lagrange polynomials, specified boundary conditions, and the desired location(s) of measurement. A simple linear combiner circuit combines the electrical outputs into the deflection velocity at the desired points.

This paper will present an overview of a new facility capable of measuring the kinematic and compliance (K&C) properties of heavy trucks. In this facility, the vehicle is positioned on the test rig and evaluated as a complete vehicle under normal loading conditions. The test rig can accommodate heavy trucks and tractors in two-axle or three-axle configurations. Kinematic and compliance characteristics of the front and rear suspensions and the steering system are evaluated as a function of vertical suspension deflection and roll, and as a function of longitudinal driving and braking forces and lateral cornering forces applied at the tire contact patch. A description of the test rig, including layout, instrumentation, actuators, and controls will be presented. The test methodology and a description of the test results will also be presented.

Abstract Aiming to improve the handling performance of heavy tractor semi-trailer during turning or changing lanes at high speed, a hierarchical structure controller is proposed and a hardware-in-the-loop (HIL) test bench of the electronic pneumatic braking system is developed to validate the proposed controller. In the upper controller, a Kalman filter observer based on the heavy tractor semi-trailer dynamic model is used to estimate the yaw rates and sideslip angles of the tractor and trailer. Simultaneously, a sliding mode direct yaw moment controller is developed, which takes the estimated yaw rates and sideslip angles and the reference values calculated by the three-degrees-of-freedom dynamic model of the heavy tractor semi-trailer as the control inputs. In the lower controller, the additional yaw moments of tractor and trailer are transformed into corresponding wheel braking forces according to the current steering characteristics.

During the past decades the public acceptance of the actual environmental legislation has gradually turned into an active support of the same. Test methods have anyhow become more cost heavy and time consuming, underlining the need of simplified tests with reasonable correlation to the legal methods. Generally, the emissions under static and semistatic load conditions are gradually eliminated, why the heavy pollution now comes from transient periods of the driving pattern. Consequently a transient test procedure must satisfy the quality requirements on a short test applicable to vehicles from cars to heavy trucks and busses. The INertia COLLection system described here is developed to enable low cost and well repeatable measurements of the emission characteristics of engine systems in light and heavy vehicles under transient load. The system is easy to adopt and does not need any chassis dynamometer.

Recently, significant focus and development effort has been dedicated toward in-vehicle networking. This effort includes work on behalf of the American Trucking Association (ATA), the Society of Automotive Engineers (SAE), the International Standards Organization (ISO), and independent developments by automotive and semiconductor manufacturers. In-vehicle networking extends, as a result, beyond passenger cars into heavy truck, military, and construction vehicles. In the course of these developments, the benefits of networking have been examined and networking is perceived as having significant benefits, resulting in production and custom development [1, 2, 3]. The Controller Area Network (CAN) is a high-performance serial communication solution which has been designed to meet the requirements for the broad range of applications and has now progressed from a specification to a product.

Abstract A kinematic modeling framework was established to predict status (position, displacement, velocity, acceleration, and shape) of a towing vehicle system with different driver inputs. This framework consists of three components: (1) a state space model to decide position and velocity for the vehicle system based on Newton’s second law; (2) an angular acceleration transferring model, which leads to a hypothesis that the each towed unit follows the same path as the towing vehicle; and (3) a polygon model to draw instantaneous polygons to envelop the entire system at any time point.