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Selecting the optimum-sized tractor
80 6.
ABSTRACTS W. J. Chancellor. Selecting the optimum-sized tractor. Trans. ASAE, 4, 411 (1969). The elements of the decision on tractor size having to do with adaptability of large equipment to small fields or row crops, alternate uses in earth moving, and other non-economic factors concerned with the physical size of the tractor will not be considered here. Only the economic advantages and disadvantages of small and large-size tractors will be quantitatively compared to provide a basis for economic optimization of tractor selection. W. J. Chancellor, J. A. Vomocil and K. S. Aref. Energy disposition in compression of three agricultural soils. Trans. ASAE, 4, 524 (1969). The compressive characteristics of agricultural soils vary significantly with moisture content. For this reason, three agricultural soils were tested in unconfined compression at various levels of moisture. In addition, one of the soils was subjected to a lateral confining stress while axial compressive stress was applied. This was done to determine the effects of the higher stress and strain levels caused by this confining stress, and to approximate the stress state that would be expected to apply for soil encountered by tillage implements at some significant depth beneath the surface.
8.
I . V . Grinchenko, R. A. Rozov, V. V. Lazarev and S. G. Volski. Wheeled cross-country vehicles. Transl. of Mono mashinostroenie, Moscow, 264 pp. (22 May 1969). The book gives a survey of the development and an analysis of the design of present day Soviet and foreign cross-country automotive vehicles, analyzes their basic parameters, the grouping of their units, design layouts for their power drive, and designs for the units of their transmissions and mobile parts. In addition, it sets forth the peculiarities of these vehicles in use. The book also examines the methods for heightening the cross-country capabilities of the vehicles. (U.S. Gov. Res. Dev. Rep., 10.9.69, AD-689950.)
9.
J . W . Hall. Soil compaction investigation--report 10, evaluation of vibratory rollers on three types of soils. U.S. Army Eng. Waterways Exp. Station Rep. 10 (Mar. 1968). Compactive effort of 3 vibratory rollers was compared to that of a 50-ton rubber-tired roller. The field tests were conducted under shelter to provide better control.over all phases of the testing program. The smallest of the 3 rollers weighed 3150 lb, had a 30 by 50 in. drum, and operated over a range of 800 to 1600 rpm. The medium roller weighed 7,000 pounds, had a 30 by 60 in. drum, and operated over a range of 800 to 1600 rpm The medium roller weighed 5270 lb, had a 38 by 84 in. drum, and operated over a range of 600 to 1400 rpm. Operating frequencies of the 3 rollers encompass the range over which present vibratory rollers operate. Each of the 3 rollers was used to compact 3 soil types: lean clay, crushed limestone, and clean sand. Each soil was compacted wet of, dry of, and at optimum moisture content. Density in sand compacted with vibratory rollers appears to be a cyclic function of coverages. The lowest frequency middleweight compactor performed the best in sand. Densities in crushed limestone and lean clay generally increased in direct proportion to the deadweight of vibratory rollers. Except in crushed limestone, vibratory rollers will not produce densities to significantly greater depth than rubber-tired rollers. For comparable lift thickness of compaction, much lighter vibratory rollers may be substituted for heavy rubber-tired rollers; however, there is a limit to the amount of weight reduction that can be achieved using vibratory rollers. (J. soil Mech. Fndns Div., Sept. 1969.)
10.
I. Holubec and P. J. Finn. A lateral deformation transducer for triaxial testing. Can. Geotechnical J., 6, 353 (Aug. 1969). As research is expanding into more detailed study of stress-strain behavior of soils in the triaxial test, it is necessary to develop new techniques for measuring more accurately loads and deformations. However, the necessary measuring equipment is not always available commercially. The writers have developed a transducerized apparatus to measure the diameter of triaxial samples, and information on the design and characteristics are presented in this research note. (Authors' summary.)
I 1. J . A . Kirtland, D. C. Andrus and W. Slabiak. An a.c. electric drive system as applied to a tracked vehicle. S.A.E. Paper No. 690442, Mid- Year Meeting (May 1969). An a.c. electric drive system as applied to a tracked, military personnel carrier is described, and data are presented on its test-bed and test-track operation. Advantages obtainable with electric drive systems include: (1) improved fuel economy, tractive capability, steering versatility, braking, etc., (2) greater design flexibility, and (3) fewer moving, wearing parts. Basically, the system dealt with comprises a brushless, rotating-rectifiertype alternator air-cooled by an integral blower, two inverters with silicon-controlled rectifiers,
ABSTRACTS W. J. Chancellor. Selecting the optimum-sized tractor. Trans. ASAE, 4, 411 (1969). The elements of the decision on tractor size having to do with adaptability of large equipment to small fields or row crops, alternate uses in earth moving, and other non-economic factors concerned with the physical size of the tractor will not be considered here. Only the economic advantages and disadvantages of small and large-size tractors will be quantitatively compared to provide a basis for economic optimization of tractor selection. W. J. Chancellor, J. A. Vomocil and K. S. Aref. Energy disposition in compression of three agricultural soils. Trans. ASAE, 4, 524 (1969). The compressive characteristics of agricultural soils vary significantly with moisture content. For this reason, three agricultural soils were tested in unconfined compression at various levels of moisture. In addition, one of the soils was subjected to a lateral confining stress while axial compressive stress was applied. This was done to determine the effects of the higher stress and strain levels caused by this confining stress, and to approximate the stress state that would be expected to apply for soil encountered by tillage implements at some significant depth beneath the surface.
8.
I . V . Grinchenko, R. A. Rozov, V. V. Lazarev and S. G. Volski. Wheeled cross-country vehicles. Transl. of Mono mashinostroenie, Moscow, 264 pp. (22 May 1969). The book gives a survey of the development and an analysis of the design of present day Soviet and foreign cross-country automotive vehicles, analyzes their basic parameters, the grouping of their units, design layouts for their power drive, and designs for the units of their transmissions and mobile parts. In addition, it sets forth the peculiarities of these vehicles in use. The book also examines the methods for heightening the cross-country capabilities of the vehicles. (U.S. Gov. Res. Dev. Rep., 10.9.69, AD-689950.)
9.
J . W . Hall. Soil compaction investigation--report 10, evaluation of vibratory rollers on three types of soils. U.S. Army Eng. Waterways Exp. Station Rep. 10 (Mar. 1968). Compactive effort of 3 vibratory rollers was compared to that of a 50-ton rubber-tired roller. The field tests were conducted under shelter to provide better control.over all phases of the testing program. The smallest of the 3 rollers weighed 3150 lb, had a 30 by 50 in. drum, and operated over a range of 800 to 1600 rpm. The medium roller weighed 7,000 pounds, had a 30 by 60 in. drum, and operated over a range of 800 to 1600 rpm The medium roller weighed 5270 lb, had a 38 by 84 in. drum, and operated over a range of 600 to 1400 rpm. Operating frequencies of the 3 rollers encompass the range over which present vibratory rollers operate. Each of the 3 rollers was used to compact 3 soil types: lean clay, crushed limestone, and clean sand. Each soil was compacted wet of, dry of, and at optimum moisture content. Density in sand compacted with vibratory rollers appears to be a cyclic function of coverages. The lowest frequency middleweight compactor performed the best in sand. Densities in crushed limestone and lean clay generally increased in direct proportion to the deadweight of vibratory rollers. Except in crushed limestone, vibratory rollers will not produce densities to significantly greater depth than rubber-tired rollers. For comparable lift thickness of compaction, much lighter vibratory rollers may be substituted for heavy rubber-tired rollers; however, there is a limit to the amount of weight reduction that can be achieved using vibratory rollers. (J. soil Mech. Fndns Div., Sept. 1969.)
10.
I. Holubec and P. J. Finn. A lateral deformation transducer for triaxial testing. Can. Geotechnical J., 6, 353 (Aug. 1969). As research is expanding into more detailed study of stress-strain behavior of soils in the triaxial test, it is necessary to develop new techniques for measuring more accurately loads and deformations. However, the necessary measuring equipment is not always available commercially. The writers have developed a transducerized apparatus to measure the diameter of triaxial samples, and information on the design and characteristics are presented in this research note. (Authors' summary.)
I 1. J . A . Kirtland, D. C. Andrus and W. Slabiak. An a.c. electric drive system as applied to a tracked vehicle. S.A.E. Paper No. 690442, Mid- Year Meeting (May 1969). An a.c. electric drive system as applied to a tracked, military personnel carrier is described, and data are presented on its test-bed and test-track operation. Advantages obtainable with electric drive systems include: (1) improved fuel economy, tractive capability, steering versatility, braking, etc., (2) greater design flexibility, and (3) fewer moving, wearing parts. Basically, the system dealt with comprises a brushless, rotating-rectifiertype alternator air-cooled by an integral blower, two inverters with silicon-controlled rectifiers,