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The ability of performance-based brake testers (PBBTsa) to accurately determine the braking capability of commercial vehicles was investigated through a field study of over 2,800 trucks and buses. Under certain conditions, good agreement was found between the observation of brake-related defects by visual inspection and the measurement of weak brake forces by a PBBT. It was determined that the PBBTs' assessment was an independent measure of a vehicle's as-is braking capability, and should not be expected to correlate well with a visual inspection under any condition. It was also determined that predictions of stopping capability should be possible combining the PBBT results of the brake force and axle load measurements with certain assumptions regarding brake application time and road/tire coefficient of friction.

Kerosene has advanced to the front rank as a fuel for the farm tractor within a decade. A heavily preponderating majority of tractors burn kerosene. The history of early oil engines is reviewed and some comparative costs of kerosene and gasoline fuel for tractors, obtained from tests made in January, 1920, are given. Kerosene tractor-engine development is then discussed. The conditions required for complete combustion are the same in principle for both kerosene and gasoline, but in actual practice a wider latitude in providing ideal conditions is permissible for gasoline than for kerosene. The four classes of commercial liquid fuels usable in internal-combustion engines are the alcohols, the gasolines, the common kerosenes and the low-cost heavy-oil fuels. The alcohols rank lowest in heating value per pound of combustible. Under existing economic conditions neither alcohol nor the fuel oils require consideration as available fuels for the tractor.

How to improve the measurement accuracy of road gradient is the key content of the research on the speed warning of commercial vehicles in mountainous roads. The large error of the measurement causes a significant effect of the vehicle speed threshold, which causes a risk to the vehicle's safety. Conventional measuring instruments such as accelerometers and gyroscopes generally have noise fluctuation interference or time accumulation error, resulting in large measurement errors. To solve this problem, the Kalman filter method is used to reduce the interference of unwanted signals, thereby improving the accuracy of the slope measurement. However, the Kalman filtering method is limited by the estimation error of various parameters, and the filtering effect is difficult to meet the project research requirements.

Vehicle interior harmony has drawn increasing attention from customers in recent years. Kansei Engineering is an effective approach to quantify the relationship between design parameters and customer perceptions of the product. This article is a continuation of our previous study on commercial truck interior harmony. Herein, we investigated the customer perception of the visual aspects of commercial truck door interior design using classification methods. This article describes how these visual impressions are related to design elements using quantification theory, a commonly used method in Kansei Engineering. The results reveal that trim material, shape, color, window shape, and map pocket are design elements that strongly affect the perception of elegance and preferences of truck drivers. The results also showed a significant difference between the perception of the truck drivers and design engineers.

Operator/crew comfort inside a combat vehicle has not had the attention and priority it truly deserves. Inside combat vehicles accommodation is often cramped and surfaces are hard and unfriendly that could easily cause injury to the occupant. Adding excessive heat to this scenario only increases the chance for failure to perform, injury or possible loss of life. The field manual 90-30, Desert Operations, states, “highest known ambient temperature recorded in a desert was 136deg F, lower temperatures than this produced internal tank temperatures approaching 160 deg F in the Sahara Desert during the Second World War”. It is a fact that a weapon is only as good as its operator. An alert operator at his or her peak efficiency tends to perform better. The effect of heat on a combat vehicle crew can be considered a continuum ranging from discomfort to heat casualty (exhaustion and heat stroke).

An air suspension has been developed to meet the needs of the Class 8 truck market of the 1980's. This design was developed to satisfy a list of objectives that conform to present and future requirements for a tandem axle rear suspension. Throughout the development program, exhaustive tests were conducted to assure successful performance and minimize the possibility of last minute tooling changes. Dual anti-sway bars contribute significantly to the dynamic performance characteristics of this suspension and, along with the full air springing, represent its most significant performance features.

This paper highlights the installation requirements for textured spray control flaps fitted to heavy duty trucks. Tractor-trailer combinations operating on wet roads at highway speeds generate visibility impairing spray clouds. A key source of this fine droplet spray formation occurs when high velocity water thrown from truck tires impacts hard surfaces such as fuel tanks or conventional smooth surface flaps. Textured flaps absorb the tread throw impact returning the water to the road surface in large droplets. This paper addresses the placement of the flaps for optimizing spray control efficiency. Special focus is placed on the practical flap fitment behind the tractor steered and drive axles and the rear trailer axle. Moreover, the need for stronger flap support systems is addressed to accommodate the greater snow accumulations characteristic with textured spray control truck flaps.

Diesel will continue to be an indispensable energy carrier for the car fleet CO2 emission targets in the short-term. This is particularly relevant for heavy-duty vehicles as for mid-size cars and SUVs. Looking at the latest technology achievements on the after-treatment systems, it can be stated that the concerning about the NOx emission gap between homologation test and real road use is basically solved, while the future challenge for diesel survival is to keep its competitiveness in the CO2 vs cost equation in comparison to other propulsion systems. The development of the combustion system design still represents an important leverage for further efficiency and emissions improvements while keeping the current excellent performance in terms of power density and low-end torque.

Over the years, commercial vehicles, especially tractor-semitrailer combinations have become larger and longer. With the increasing demand for their accessibility in remote locations, these vehicles face the problem of off-tracking, which is the ensuing difference in path radii between the front and rear axles of a vehicle as it maneuvers a turn. Apart from steering the rear axle of the semitrailer, one of the feasible ways of mitigating off-tracking is to shift the fifth wheel coupling rearwards. However, this is limited by the distribution of the semitrailer’s load between the two axles of the tractor; any rearward shift of the fifth wheel coupling results in the reduction of the total static load on the tractor’s front axle and hence available traction. This may in turn lead to directional instability of the vehicle. In the present work, a new model of the fifth wheel coupling is proposed which the authors call Split fifth wheel coupling (SFWC).

The Kinematical models and Emulation of muti-axle steering of off-highway vehicles had been researched in this paper,that included the kinematical model of dozens of steering linkages, the relationship model of the steering linkages, the minimum steering radius and the wheel alignment, the mathematical model of the steering linkages and the steering system, and the model of the stability of the vehicle. The theory and method of the linkages optimization of multi-axle vehicles had been researched with kinematics theory. The simulation had been done on the multi-axle steering linkages of a eight-axle(8 X 8) off-highway vehiele, and the optimal parameters of the linkages had been obtained accordin to the simulation result and the optimal theory.

In this paper, a Magneto-Rheological (MR) fluid semi-active suspension system was tested on a commercial vehicle, a domestic light bus, to determine the performance improvements compared to passive suspensions. MR fluid is a material that responds to an applied magnetic field with a significant change in its rheological behavior. When the magnetic field is applied, the properties of such a fluid can change from a free-flowing, low viscosity fluid to a near solid, and this change in properties takes place in a few milliseconds and is fully reversible. A quarter suspension test rig was built out to test the nonlinear performance of MR damper. Based on a large number of experimental data, a phenomenological model of MR damper based on the Bouc-Wen hysteresis model was adopted to predict both the force-displacement behavior and the complex nonlinear force-velocity response.

The catalytic conversions of diesel exhausting particulates (DEP) are studied in this paper. The oxidation catalysts, carried by Y-Al,O, pellets, are prepared with the method of impregnation. By use of thermo-gravimetric analysis (TGA) technique, the catalytic abilities of these catalysts are studied and the igniting characteristics of DEP are determined. A mathematical method is introduced to process TGA experimental data furtherly. Some equations have been derived to evaluate the kinetic parameters of the oxidation reaction of DEP. By comparing the activation energy (Ea) of the reaction and the igniting temperature (Ti) of DEP, the catalytic activities of the oxidation catalysts are evaluated.

Chassis dynamometer testing of two 60 foot articulated transit busses, one conventional and one hybrid, was conducted at the National Renewable Energy Laboratory's, ReFUEL facility. Both test vehicles were 2004 New Flyer busses powered by Caterpillar C9 8.8L engines, with the hybrid vehicle incorporating a GM-Allison advanced hybrid electric drivetrain. Both vehicles also incorporated an oxidizing diesel particulate filter. The fuel economy and emissions benefits of the hybrid vehicle were evaluated over four driving cycles; Central Business District (CBD), Orange County (OCTA), Manhattan (MAN) and a custom test cycle developed from in-use data of the King County Metro (KCM) fleet operation. The hybrid vehicle demonstrated the highest improvement in fuel economy (mpg basis) over the low speed, heavy stop-and-go driving conditions of the Manhattan test cycle (74.6%) followed by the OCTA (50.6%), CBD (48.3%) and KCM (30.3%).

Knock limitations are investigated using natural gas, with diesel pilot ignition, as a fuel for the 3406 DI-TA Caterpillar diesel engine. Thermodynamic properties at TDC are generated by computer and compared with experimental results. Exhaust emissions are analyzed. A comparison is made of dual-fuel operation relative to diesel. Observations are made to determine the onset of knock. The onset of knock is characterized as a function of engine speed, load, inlet manifold temperature, and air-fuel ratio (A/F). The conditions at the onset of knock are determined using cylinder pressure data. The most efficient operating range is determined with knock avoidance as a prime parameter.

Reduction of carbon dioxide (CO₂) emission, which causes global warming, is an important guideline for vehicle engine development. There are two types of methods for reducing the CO₂ emission of a vehicle engine. The first involves improving engine efficiency. The second involves the use of a low-carbon fuel, i.e., fuel with high hydrogen to carbon ratio. Hydrogen-compressed natural gas blend (HCNG) has been researched as a low-carbon fuel. Given that thermal efficiency of an engine cycle increases with its compression ratio (CR), an HCNG engine with high compression ratio not only has high efficiency but also low CO₂ emission. However, unexpected combustion such as knock could occur owing to the increased CR. In this study, we investigated the knock and emission characteristics of an 11-L heavy-duty HCNG engine with a modified CR. A conventional CNG engine was fuelled with HCNG30 (CNG 70 vol% and hydrogen 30 vol%).

Kubota introduced a 14.9kw(20HP) multi-purpose compact tractor in 1989. This tractor was developed to perform light duty applications requiring loader, backhoe, and scraper capabilities as well as operations that require a 3-point hitch or a rear PTO. The design of tractor, loader, and backhoe was originally targeted to be especially suitable for agricultural and light duty industrial applications. The effort was to improve operating efficiency, ease of operation, and operator comfort. “AUTORETURN” system was adapted into the backhoe. Electro-hydraulic control technology reduces the need for operator skills. The detailed description of this technology as applied to multi-purpose compact tractor is described in the body of this report.

Soil bin tests were used to begin development of a side force prediction model for agricultural tires on soil. Previously published equations can be used for tractive force prediction in the SAE coordinate system. The friction ellipse concept can be applied to tires operating on soil.

LDA technique was used to investigate valve exit flow and in-cylinder flow generated by a directed intake port of a heavy duty Diesel engine under steady and unsteady conditions. The results obtained under both steady and unsteady show the flow patterns is very sensitive to the valve lift with this type of intake port. At small valve lift, flow profile around the valve periphery is relatively uniform, the corresponding in-cylinder flow is characteristic of double vortex. With valve lift increasing, the separating region appears near the valve seat in part of the valve periphery, therefore the flow pattern begins to depend on the position around the valve periphery. As a result, the valve exit flow is almost along the elongation of intake port at the maximum lift, the corresponding in-cylinder flow behaves as a solid body of rotation. The motion of valve seems to have little effects on the valve exit flow pattern.

The measurement of transfer port efflux velocities using laser doppler velocimetry (LDV) in a motored model two-stroke engine is described. The single cylinder engine used is of two port loop scavenged design, externally blown to provide scavenge flow into the cylinder during the entire port open period. LDV measurements were taken along a vertical path, central to the transfer duct, at the port exit over a range of crankangles at motoring speeds of 225rpm, 600rpm, and 900rpm. At 225rpm further measurements were taken for a range of delivery ratios from 0.7 to 2.0. Relatively uniform velocity profiles indicate plug like flow issuing from the port under most conditions. The resultant flow direction is seen never to align with the transfer duct walls, but to vary as a function of crankangle. Quantitative analysis of angles defining mean flow direction reveal that dynamic efflux behaviour is essentially similar for all tested speeds and delivery ratios.