Search Results

A method of predicting the tractive performance of a tracked vehicle has been developed through a combined program of analytical modeling, field testing and model verification. This method uses field test data to establish parameters that describe the track/soil interface. Once these parameters are established, the analytical model can then predict changes in tractive performance resulting from changes in vehicle configuration and operating conditions.

The material presented in this paper addresses the following questions of the engineer of the ‘80’s: 1. How can an (earthmoving) engineer be successful in the ‘80’s? 2. Should he isolate himself in his work? 3. Are there special needs in the ‘80’s? 4. What should he do-personally-to succeed and to improve the world in which we live? 5. Can the engineer help solve specific problems facing us now? 6. Can today’s problems-unemployment, inflation, world unrest, competition from new sources around the world, social unrest, energy limitations, pollution, and others, be met directly by the engineer with any success?

The current state of the art in truck wheel technology is reviewed with particular emphasis on rims. The salient design features of both single and multipiece rim types are described and the safety of both types in the context of field performance is explored. Some aspects of contemporary design methodology are discussed and possible future directions for the technology are forecast.

The newly mass-produced EQ 140 truck is designed for difficult service conditions existing in China. The policy of material selection is to ensure good quality of the truck and to make full use of resources rich in the country. In order to beneficially exploit the full value of cast iron, RE-Mg treated irons are employed. Wide application of high strength steels makes the truck more durable and lighter. For good hardenability, a series of boron steels is developed to save large amount of precious alloys. The success of the truck proves that the policy of selection and development of materials is well-based both technically and economically.

This paper presents an experimental study on the brake noise having a main frequency of about 500 Hz. From the vibration modes of the brake components during the brake noise occurrence, some resonance systems which might be the cause of the noise were considered. As a result of investigating these resonance systems experimentally, the resonance system which concerns to the noise was found out. From the resulting evaluation of the noise by changing the vibration characteristics of the resonance system through modification of the brake components, it was found that the spring constant and the damping coefficient of the wheel brake component correlate well to the brake noise level. Using these correlations have made it easier to improve the brake noise.

The future shortages of energy, real energy price rises and inflation are seen as some of the most pressing problems facing the world economy. The recognition of these concerns in Australia will result in pressure to maximise the efficient use of transport fuels. Efforts to optimise the Refinery/Vehicle Engine/Fuel System will lead to changes in petroleum product mix and fuel specification. A principal area for development to improve commercial vehicle fuel efficiency is aerodynamic drag reduction. The benefits of medium truck aerodynamics are demonstrated. There is also a case to argue for transport efficiency improvements through increased loadings.

A structural analysis procedure using shock spectra loading has.been used as a design tool for truck and trailer mounted refrigeration unit frames. The units experience shock and vibration from highway, rail and ship transportation. The loading information has been obtained from a thorough investigation by NASA of transportation loading in cargo areas. The procedure consists of computing stresses in the frames with a finite element model. Both the static equivalent load method and the response spectrum method have been used. The static equivalent load method consists of using the peak acceleration value multiplied by 1.5 to account for dynamic amplification. The response spectrum method selects the acceleration load according to the frequency domain and combines stresses based on the square root of the sum of the squares (SRSS) rule for modes and directional components.

A comparison of tag-tandem versus drive-tandem operating considerations is provided. These considerations include fuel economy, traction, and other operating characteristics. Fuel economy testing using the SAE Type II procedure indicates there is statistically little or no difference between drive-tandem and tag-tandem fuel economy. A traction analysis comparing the gradeability of the two axles demonstrates the superiority of the drive-tandem axle. Recommendations for the truck operator are given.

A mobile dynamometer for measuring the longitudinal force acting at the fifth wheel connection between a tractor and a semitrailer has been developed. The use of this dynamometer for testing retarders installed in tractors is described and example results are presented. Computational methods for predicting total retardation of various vehicles equipped with retarders are discussed.

Through the use of microelectronics the diesel truck can be more accurately and easily controlled. With the increased flexibility in timing it is possible to achieve a better fuel consumption vs. exhaust emissions strategy. With increased timing accuracy the engine is kept closer to the design optimum throughout its life. Through reprogramming at the engine factory, many specifications can be handled with one type of system and inventory. Field testing of the American Bosch microprocessor controlled governors has proven a number of convenient operation and driveability features as well.

Retarders have traditionally been credited with reducing brake maintenance costs of large trucks and lowering trip times. This paper presents methods for quantifying the resulting productivity increases. A Brake Life Extension Factor is developed and shown to increase as retarder horsepower increases. Four common retarder technologies are discussed (exhaust brakes, engine brakes, electric retarders and hydraulic retarders). A method is shown for computing the return on investment in a retarder, based on only the brake maintenance savings, using a discounted cash flow analysis. The impact on capital of faster trip times is examined.

Retarders of various kinds to augment the braking system for trucks and buses can lead to three economic benefits: brake wear may be reduced, so that long-term maintenance costs will be lower; speed of travel on long downgrades may be increased, leading to shorter total trip time; and the probability of a runaway accident may be reduced, with consequent savings in damage and injury. All of these potential savings depend on the typical trip profile for the vehicle in Question. In this paper the likely benefits in reduced brake maintenance, productivity, and accident reduction are computed for a variety of trucking operations, and data are furnished in enough detail to permit a particular user to estimate the value of adding retarders to his vehicles.

This paper develops and discusses a digital computer simulation model of a total vehicle drive system. The vehicle studied utilizes a single hydrostatic engine, pump, fluid conductor, motor, wheel, soil, and weight transfer details. A model such as this can be used to investigate vehicle dynamics; various transmission control characteristics; the effects of major system changes, etc; and work that would otherwise require actual vehicle build-up, modification, instrumentation, and testing.

Recent growth in automotive applications of electronic instrumentation systems has been accompanied by only limited application of similar electronic products in the light truck industry. This paper offers a brief overview of currently used automotive electronic display information systems and discusses the potential adoption of these systems into the light truck/recreational product area. Value to today’s noncommercial truck owner is evaluated as well as the potential value to commercial vehicle operators.

The market characteristics for the application of electronics for engine controls on heavy duty trucks is characterized. The system performance and environmental design requirements are established and a mechanization implementing these requirements is described.

Controls are the key to meeting increasing transmission and diesel engine performance needs. Customer demands for optimum vehicle performance and rapidly increasing number of differing heavy duty transmission applications are pushing present hydraulic controls to their limits, and require the current controls be specifically calibrated for the various applications. A microcomputer-based control system can overcome these limitations and also provide performance improvements. Application of the microcomputer for truck and bus transmissions is of considerable interest at this time as it has already been developed for the automobile industry, thus assuring high reliability and a large production base to minimize cost.

The decision to use a microcomputer in an automotive application is often far easier than the choice of which particular microcomputer to use. The wide range of applications places an equally wide range of demands on the microcomputer. Three application examples (engine control, antiskid braking, and dashboard control) will be used to demonstrate how a microcomputer can be selected for a given application by a combination of classical benchmarking techniques and key feature extraction.

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.

Telebus II is a low floor construction vehicle especially designed for the transport of physically disabled passengers. Its design allows for all kind of problems in connection with wheel chair drivers. The main characteristics being a vehicle body which can be lowered to road level so that disabled passengers can enter the car via a front resp. lateral right hand door without outside help. Special restraint systems for wheel chairs as well as special purpose seats for the disabled are standard equipment. The vehicle has a self-supporting superstructure, independent air suspension and is powered by a transverse rear 65 kW Diesel engine with automatic transmission.