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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.

In support of the Department of Energy ( DOE) "SuperTruck" program, a group of low energy, high output light emitting diode (LED) lamps were developed for forward lighting. Reduction of the energy needs of the truck by saving fuel and reducing CO₂ emissions are two of the goals of this program. In support of the energy reduction, a retrofit LED headlamp was designed, built and tested. The retrofit headlamp was switched from a halogen bulb to an LED-based system. The LED headlamp requires a new approach in heat management. The use of the LED, which is a 2π source, requires a different strategy in the optics from those used with a 4π source, like a traditional incandescent, halogen, or High Intensity Discharge (HID) light source. A thermal management system is necessary to facilitate the long life of the LED source. A unique method for removing the heat of the LED and maintaining an acceptable temperature was tested and reported.

Light Emitting Diodes (LEDs) are commonly used for signaling and marking functions on commercial vehicles. Recent work on new LED modules will allow the use of LEDs for illumination functions.

Today, LED automotive exterior lighting is already widely used on high end and upper middle class vehicles. We see already first examples of application as the standard lighting solution even in the mid class segment. A compact design and the feasibility of car life sealed solution is a strong argument to use LEDs for CHMSLs. Long lifetime and new styling opportunities speak for LEDS in front or rear position lights as well as in daytime running lamps;. Mainstream penetration of LED lighting solutions will first happen for functions where the benefits of LEDs have the highest positive impact and where this value can be realized in the most cost-effective way. During the different phases of the introduction of LEDs different requirements dominate the decision process. Providing unique styling opportunity and showing advanced technical functionality is leading for the early adopters.

The title of this paper fully indicates its scope. The author presents an intimate picture of conditions prevailing at the war front which affect the operation and maintenance of war trucks, and these two factors in turn indicate the trend that design should take. The training of the mechanical transport personnel of the Army is also gone into at some length. The English and American trucks used earlier in the war consisted of about nineteen different makes and forty-two totally different models, resulting in a very serious problem of providing spare parts and maintenance in general. In the British Army transportation comes under an Army Service Corps officer called the Director of Transport and Supplies. At the outbreak of the war these officers had had little mechanical experience, horses being employed principally. In the French Army motor vehicles were used to a greater extent before the war, under the artillery command.