Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 87-88).

Thesis (Ph. D.)--Purdue University. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 66).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 288-291). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [111]-118.

Thesis (M.S.)--Humboldt State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 54-56).

Trucking of forest products is a very important segment of the harvesting process and it is monitored relatively closely by external sources. Load weight is the focal point of the attention received by log hauling. The optimization of load weights is therefore very important to a logging operation's success and this can be achieved only through adequate gross vehicle weight control. Methods of load weight control are reviewed and possible applications discussed in this report. Studies were conducted to evaluate the adequacy of load weight control achieved utilizing two quite different methods. A reporting technique which provided loader operators with information about trends in the delivery weights of trucks which they loaded was used to heighten their awareness of problem areas in load weight distributions. This study was conducted at two southern paper mills with substantially different truck weight regulation environments. Two separate case studies were conducted on Virginia loggers utilizing on-board electronic truck scales. Results of the loading study indicated that the passive treatment had affected the behavior of some of the producers studied. The behavioral changes observed generally improved the economic optimization of load delivery weights. The on-board scale studies indicated that the scale systems did perform well in the applications observed. However, the economic benefits associated with use of the scales were negligible for the two producers studied due to a reduction in delivery weights after installation of the scales. / Master of Science

Studies of log truck speeds and fuel consumption were made at four location in the southeastern United States. Execution of the study necessitated the development and testing of a microprocessor based data logger capable of withstanding the harsh operating environment found in forest harvesting and transport equipment. The first study investigated the normal operating pattern for a truck in a logging contractors flect. The truck was found to be highly utilized and to incur considerable distances of unloaded running to service the contractor's widely separated operations. A second study highlighted the fucl and speed penalties associated with operations on sand and gravel roads. The third study documented significant performance differences between routes delivering to one location even where road surface differences were minimal. A fourth, detailed study illustrated speed and fuel consumption differences between urban and mural operations. Tests on a group of five experienced drivers demonstrated considerable differences in speed and fuel usage. Some drivers appeared to have a driving style which delivered higher speed with low fuel consumption. A detailed analysis of individual speed profiles indicated that as much as 1/3 to 1/2 of the recorded fuel consumption on one section was associated with air resistance. In conclusion the studies noted that for the trucks and conditions evaluated: (1) there are significant performance losses and increased costs associated with operations on low standard road sections. Road roughness was a significant factor determining speed. (2) performance and cost differences between routes were demonstrated even for roads of comparable road surface type. This indicated that inter-route costs differences may be pervasive. These differences would require acknowledgement and evaluation if equitable route payment schedules were to be constructed. (3) All the trucks studied operated for at least part of the time at high speeds and may be incurring unnecessary fuel and maintenance expenses. Application of aerodynamic deflectors might be beneficial and their applicability should be tested. (4) Some driving styles appear more efficient and deserve further investigation and documentation. Changing driver behavior might present the most cost effective means of improvement in fleet performance. / Ph. D.

A mechanical design of an ultra-light log trailer was performed. The design process necessitated the experimental measurement of dynamic loads exerted on a log trailer and a comprehensive stress analysis of the structure. Two light-weight, prototype, log trailers were selected to be studied, after an exhaustive survey of the existing designs. Finite element models (FEM) were developed for each of the trailers using three-dimensional tapered unsymmetrical beam elements. Static stress analysis was performed to identify critical spots in the structures and to estimate stresses encountered at these locations. These spots were selected as strain gage placements for the experimental dynamic stress analysis. A special data acquisition system based on the STD bus computer was designed, assembled, programmed, and tested for the experimental force and strain measurements. Experimental stress analysis of each of the selected trailers was performed. Dynamic loads and the resultant strains at critical locations were measured, both while simulating extreme situations, and during typical work cycles. The recorded service stress-time histories were then used to identify peak values of the maximum dynamic loading and the structure response. Stress distributions throughout the structures were obtained using the FEM models. The recorded service load spectra were then utilized to assess a fatigue life of each of the tested designs. A survey of log trailers for fatigue cracks was conducted when the dynamic stress analyses indicated that a log trailer is most likely to fail due to repeated loading. The causes for fatigue cracking of log trailers were then investigated through elastic shell element FEM modeling. Finally, an efficient and economically feasible ultra-light design was developed based on the formulated recommendations. The most important features of the proposed design are: 1. Reduced tare weight of 7,770 pounds. 2. Sound structural integrity. 3. Material of high strength and toughness used throughout. 4. Improved fatigue resistance (e.g., welds were replaced by elastic friction joints). 5. Movable bunks. 6. Replaceable bolsters and standards. 7. Constant tensioning device for load binders. / Ph. D.

The potential for decreasing timber transportation costs in the South by increasing truck payloads was investigated using a combination of theoretical and case-study methods. A survey of transportation regulations in the South found considerable disparities between states. Attempts to model the factors which determine payload per unit of bunk area and load center of gravity location met with only moderate success, but illustrated the difficulties loggers experience in estimating gross and axle weights in the woods. A method was developed for evaluating the impact of Federal Bridge Formula axle weight constraints on the payloads of tractor-trailers with varying dimensions and axle configurations. Analysis of scalehouse data found log truck gross weights lower on average than the legal maximum but also highly variable. Eliminating both overloading and underloading would result in an increase in average payload, reduced overweight lines, and improved public relations. Tractor-trailer tare weights were also highly variable indicating potential for increasing payload by using lightweight equipment. Recommendations focused first on taking steps to keep GVW’s within a narrow range around the legal maximum by adopting alternative loading strategies, improving GVW estimation, and using scalehouse data as a management tool. When this goal is achieved, options for decreasing tare weight should be considered. Suggestions for future research included a study of GVW estimation accuracy using a variety of estimation techniques, and field testing of the project recommendations. / Ph. D.

M.S.