Heavy Wheel Research Articles

Mechanized unit with aerostatic bearings for balancing heavy Pump wheels with a straight rear wall

Mechanized unit with aerostatic bearings for balancing heavy Pump wheels with a straight rear wall

Calculations and Experiments on the Unbalance Response of a Flexible Rotor

The results of a combined analytical and experimental investigation of the unbalance vibrations of a rotor are presented. The analysis applies to a general rotor-bearing system in which the dynamic bearing forces are represented by four spring coefficients and four damping coefficients. The rotor can be represented as either a lumped or a distributed parameter system, and gyroscopic moments are included. In general, the unbalance whirl motion of the rotor will be elliptical. The analysis has been programmed for a digital computer to obtain results for comparison with the experimental data. The test rotor is a uniform, flexible shaft with heavy wheels mounted at the ends and in the middle. The rotor is supported in two silicone fluid-lubricated, tilting-pad bearings. The rotor amplitude caused by an induced unbalance has been measured over a speed range of 3000 to 24,000 rpm for three different rotor configurations, obtained by removing one or both end wheels. This speed range extends to or through the third critical speed for each of the rotor configurations. The results are compared with the theoretical values and, in general, the agreement is found to be good.

Trafficability tests with two vehicles with 9- to 10-ton wheel loads

SOIL trafficability studies have been in progress at the U.S. Army Engineer Waterways Experiment Station (WES) since 1946. The results of these studies have been reported in Technical Memorandum No. 3-240, Trafficability of Soils, and 17 supplements thereto, and in other technical reports and miscellaneous papers. The early phases of the work were primarily studies of fine-grained soils. In 1955 the methods and techniques of measuring the trafficability of fine-grained soils were considered to be essentially complete, and a summary report was published[ 1 ]. This repoa contained formulas for computing mobility indexes and determining the soil strength requirements for all military vehicles in existence at that time (1955). Since 1955 there has been a trend toward extra-large, high-flotation tires on small vehicles and extra-heavy wheel loads on large vehicles, in contrast to the more familiar military designs of 21⁄2and 5-ton 6+6 trucks with standard military NDCC tires. Examples of the use of extra-large, high-flotation tires on small vehicles are terra tires used as replacements for conventional tires on 1/4and 3/4-ton trucks. Examples of extra-heavy wheel loads are the 25to 50-ton wheel loads of the B A R C and approximately 10-ton wheel loads of the 16-ton GOER vehicles. Limited data from tests conducted with vehicles mounted with constructionequipment-type tires--a Tournadozert, a 5-ton GOER [2], and a 5-ton Jumbo truck [3 ]--and results of test programs conducted by other agencies, such as Project Wheeltrack [4] and Swamp Fox II [5], indicated that heavy vehicles were immobilized on soil strengths that should have been adequate according to the published formulas. To determine if revisions were needed in the existing mobility index formulas for self-propelled wheeled vehicles, tests were conducted with small, lightweight vehicles mounted with high-flotation tires and with heavy vehicles mounted with construction-equipment-type tires. This paper deals only with the tests conducted with two of the heaviest vehicles. The specific objectives of the tests reported herein were to (a) determine experimentally the minimum soil strength requirements for go (on a 50-pass basis) of two vehicles with 9to 10-ton wheel loads, (b) compare the experimentally determined strength requirements with predicted strength requirements, and (c) investigate the interrelations of repetitive traffic of vehicles with heavy wheel loads and soil strength.

Citizen Organization for Control of Government

forth their specifications for American governments at various levels and assign a great array of tasks to the voters in serene, unthinking disregard of the fact that the sovereign voters may or may not deign to exert themselves to perform all those tasks. When, as so frequently happens, the voters ignore a given assignment, the fashion is to denounce the voters for apathy, as a builder of a mill wheel might petulantly denounce a stream which fails to turn his heavy wheel in a dry summer. Thus, when the writers of Michigan's constitution provided that the state treasurer should be chosen by the voters, the voters promptly and perpetually ignored the assignment; only 4 per cent of them were able to name him when an official committee took a careful poll in 1950.1 Having such an obscure and relatively small office on the elective list would work if the people would do the task thus assigned. Since they will not, there is no justification for retaining the office as elective, no reason for perpetuating a setup which has never worked. Yet the very commission which uncovered the fact of mere 4 per cent awareness bowed to the sacred cows of politics and shrank from the logical remedy of assigning to the governor the function of filling that office. And when the great bulk of voters thus ignore an elective office, a few politicians proceed to fill it, dealing with it as part of their own private

Design Curves for Single Wheel Loads

As explained in a previous paper, the CBR design curves for heavy wheel loads were extrapolated from highway data in the initial stages of the airfield construction program. Subsequently, the curve...

Cross-Current Predeterminations from Crank-Effort Diagrams

Abstract This paper is a research study into the cause of excessive cross-current flow between paralleled alternators when driven by reciprocating engines. Cross-currents determined by ammeter measurement show a flow far greater than can be traced directly to the unevenness of the primary crank-effort forces. The uneven crank effort of the reciprocating engines does, however, superimpose small oscillatory displacement movements upon the rotating paralleled armatures, which in turn cause a correspondingly small cross-current flow, the pull of which is still sufficient to set up independent armature oscillations. The time period imposed by the cross-current pull differs from that imposed by the primary crank-effort forces, and the reactive effect is a periodic variation in the engine load against which the uneven crank effort must work. This condition is shown to be conducive to cumulative armature-displacement movements, since at times these two distinct periodic forces, i.e., excess effort and cross-current pull, act in unison, while subsequently they act in opposition. The combined action of these two forces subjects the rotating wheel parts to a cumulative oscillatory movement, the amplitude of which may readily build sufficiently to account for the relatively heavy cross-current flow found by actual measurement. The theory underlying cumulative motions of this kind is developed, and formulæ are derived for predetermining the maximum armature-displacement shift and accompanying cross-current flow that may be expected for any given set of conditions. The character of motion and the maximum amplitude of such cumulative oscillations are found to depend largely upon the relation which the time period of the excess crank effort bears to that of the cross-current pull. The crank-effort period is fixed by the cylinder arrangement and engine speed, while the cross-current-pull period is found to be most readily controlled by the selection of a suitable wheel weight. The wheel-weight constants prescribed for paralleled reciprocating-engine units provide a guide for confining the cumulative armature oscillations within satisfactory limits. When a relatively light wheel is used for such engines, the resulting oscillatory movement is likely to have a comparatively rapid period and its maximum cumulative amplitude may be expected to be approximately twice that which occurs when using a heavy wheel oscillating with a relatively slow period. The author advocates a reasonably heavy wheel as most likely to obviate excessive cross-current flow, mainly because of its beneficial secondary effects. The greater maximum amplitude of oscillation in the case of the relatively light wheel may lead to serious electrical disturbances, and under adverse conditions the detrimental secondary effects of the more rapid cumulative oscillations may become so aggravated as completely to upset the regulating functions of the engine governor. The characteristic behavior of paralleled alternators is briefly set forth in the Appendix by means of vector diagrams. Therein is also discussed the manner in which periodic displacement movements of the paralleled armatures affect a momentary change in engine load. The paper further treats of the principles underlying harmonic motion as applied to the effect which uneven crank-effort forces exert upon the rotating wheel mass. Wheel-displacement increments, graphically determined, are compared with those approximated by the more direct method of calculation. In discussing the subject of harmonic armature oscillations and their application to paralleled alternators, the author points out reasons for considering untenable some of the basic assumptions made in the German literature relating to this subject. Cross-current determinations made by the author upon a set of paralleled 500-hp. gas engines are analyzed with the view of substantiating the contention as to the defect in the Rosenberg theory, and Bonte’s deductions based thereon.

Studies in Spicule Formation. : VII.—The Sclerohlastic Development of the Plate-and-Anchor Spicules of Synapta, and of the Wheel Spicules of the Auricularia Larva.

(1) The spicule first appears as a granule contained in a syncytium, in which, however, the scleroblasts retain their individuality to some extent, which is not the case in the syncytium of Synapta. (2) The spicule becomes disc- and then cup-shaped, develops the spokes as outgrowths from the margin of the disc, and finally forms the felly of the adult wheel, the spicule during the whole of its development being enclosed by the syncytium in which all the nuclei (scleroblasts) are situated on its internal side, i. e. away from the body-wall against which the spicule lies. (3) The extension of the scleroplasm depositing the spicule is determined by the growth of the spicule itself, and is not the result of a mould-forming tendency on the part of the protoplasm, as Chun asserted. (4) The situation of the heavy wheel and globe spicules at one (the lower) extremity of the larva determines the position which the larva assumes in the water--the spicules weight the larva.

Studies in Spicule Formation

(1) The spicule first appears as a granule contained in a syncytium, in which, however, the scleroblasts retain their individuality to some extent, which is not the case in the syncytium of Synapta. (2) The spicule becomes disc- and then cup-shaped, develops the spokes as outgrowths from the margin of the disc, and finally forms the felly of the adult wheel, the spicule during the whole of its development being enclosed by the syncytium in which all the nuclei (scleroblasts) are situated on its internal side, i. e. away from the body-wall against which the spicule lies. (3) The extension of the scleroplasm depositing the spicule is determined by the growth of the spicule itself, and is not the result of a mould-forming tendency on the part of the protoplasm, as Chun asserted. (4) The situation of the heavy wheel and globe spicules at one (the lower) extremity of the larva determines the position which the larva assumes in the water--the spicules weight the larva.

The Advantages of a Longitudinal Bearing System for Railway Tracks

It is now admitted by civil engineers and other railway experts, that our American system of track which has done so well in the past, owing to its strength, elasticity. and economy of first cost and maintenance, is now in a bad way, and must be modified in some manner to meet the ever-increasing weight of cars and engines. This has grown during the last fifteen years from 5 tons on a locomotive driver to 9½ tons; and 3 tons per car wheel to 5½ tons; and the encl is not yet. Our track is giving out at all points. Joints which did well under lighter loads, now sink and allow rail ends to be battered down. Steel rails are not hard enough. Their heads crush, or the material itself flows under the heavy wheel loads.