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The overspeed capability of the large steel flywheels used on light water reactor primary coolant pumps has been evaluated through a combined analytical and experimental effort. Limiting speeds of the prototype flywheel design were calculated for the ductile failure mode using the principles of Section III of the ASME Boiler and Pressure Vessel Code, and for the brittle fracture mode using a fracture mechanics approach in which stress intensity factors were determined from finite element computer analysis. The accuracy of the analytical approach was verified by a scale model test program which demonstrates excellent agreement between experiment and analysis. The results of the evaluation are presented in this paper, and they illustrate the kinds of things which can be accomplished through application of modern fracture mechanics technology, including plasticity considerations, to the solution of hardware problems of real engineering interest.

A solution of the problem of optimal stabilization (in a specific sense) of the rotational motion of a gyrostat (a solid with two flywheels) in a central Newtonian force field is given within the framework of analytical control theory [1].

The cycloconverter provides a novel means for the speed control of a wound-rotor machine. When the wound-rotor machine is coupled to a large flywheel and the cycloconverter is used for control, the effects of cyclic loads on an ac power system can be compensated by ``pumping'' energy into and out of the flywheel.

The acceleration power spectra and structural resonance conditions were examined for a non-isolated medium sized chain saw. The results of the tests indicated that vibration at the frequency corresponding to the operating speed of the saw was primarily due to the fundamental shaking forces caused by the unbalanced reciprocating masses of the slider-crank mechanism and the rotating unbalance of the clutch and flywheel of the saw. The vibration response at frequencies corresponding to the harmonics of the fundamental shaking forces was amplified because their frequencies coincided with the structural resonant frequencies of the saw. Many, if not all, of these structural resonant frequencies were excited by the pulses created by the exploding gas—air mixture of the internal combustion engine. The test results indicated that the interaction of the cutting chain and wood during cutting operations contributed little to the overall vibration response of the saw.

A concept is presented of a rotating artificial gravity system for manned orbital vehicles and stations which requires no expenditure of propulsive mass to attain full-vehicle rotation. The device proposed is a deployable reaction flywheel of large radius, consisting of small weights at the ends of light flexible cables driven by a motor through the leading action of cranks at the "flywheel" hub. Deployment and retrieval techniques are described. The device can be applied to most full-vehicle rotation configurations that have been proposed in the past, making it possible to start and stop rotation frequently for a negligible amount of hardware weight and power. This makes it practicable to schedule frequent periods of vehicle rotation for crew gravity therapy and convenience of operations such as internal maintenance 011 a minimum interference basis with periods of nonrotation for such operations as observation, experimentation, maneuver, rendezvous, and docking. Nomenclature /) = cable equivalent diameter, in. E = kinetic energy, ft-lb G = acceleration, g g = gravitational acceleration, ft/sec2 HP = horsepower / == moment of inertia, slug-ft2 I = crank normal offset, ft R — radius, ft s = stress, psf Sr = specific reactant consumption, Ib/kw-hr T = tension, Ib t = time, sec V = velocity, fps W = weight, Ib 77m = mechanical efficiency co = angular velocity, rad/sec Subscripts^

Two criteria of satisfactory systems performance are the ability of the main generator to retain stability and the ability of the exciter set to recover after a disturbance. Normal emergency throw-over times are generally between one and two seconds. This study indicates that for these throw-over times a very substantial margin in system performance exists, with the use of a special design of motor-driven exciter set with an inertia constant H of 5 and a maximum torque of about 325 per cent rated. This exciter set does not require a shorter throw-over time than any other essential station auxiliary. The high torque characteristic of the induction motor enables satisfactory system performance to be obtained with voltage at the motor terminals as low as 70 per cent of normal both on steady state and on re-energization after throw-over. With this exciter, for a 3-phase short-circuit fault at or near the generator terminals, the maximum permissible switching time closely approaches the actual critical switching times which vary between approximately 11 and 20 cycles for the conditions studied. Practical switching times are generally below ten cycles. Additional special design considerations of the exciter set as presented in reference 1 further improve performance for the short-circuit fault operation.

Experiments on the pressure of air in the neighbourhood of a flywheel running in contact with a flat tangential board are described to exhibit the properties of a compressible lubricant. A comparison of the compressibilities and viscosities of the vegetable and mineral oils leads to the conclusion that the special property of oiliness is the physical property of incompressibility. In Note II. Worthington's experiments on the adhesion of two solids immersed in a stretched liquid are explained as an illustration of the phenomena of lubrication in a stretched liquid. In Note III. the effect of glass beads, &c., in promoting the free boiling of air-free water is explained by the occurrence of cavitation behind the moving beads, &c., the steam entering the cavities thus produced and dilating them into large bubbles.

It is the purpose of this paper to examine the need and design of arc-welding reactors for d-c arc-welding sets. The inductance useful in stabilizing welding arcs is defined, and methods for calculating and measuring this quantity are suggested. Further, criteria for designs which make most effective use of material are established. Finally, a recent development in reactor design is described.

The history of extended periods of lost experimental time, due to mechanical and electrical failures in the flywheel motor-generator (M-G) sets used by pulsed synchrotron magnets, indicates a necessity for standby facilities. The idea of pulsing synchrotron magnets directly off the utility lines without interposing a flywheel M-G set has become very active in recent years. Investigations have shown this to be an extremely attractive alternative for the Zero Gradient Synchrotron (ZGS). The switchover, in the event of an M-G set failure, can be made within a matter of hours; the first costs are lowest, operating costs are reduced and reliability is increased; and it can be built in stages from partial energy to full energy capability. The first phase will be to install a 35 MVA transformer capable of pulsing the ZGS to an energy of 9 GeV with a line voltage fluctuation of less than 1%. Low voltage taps will be available for low energy pulsing to study the effects on the utility system. The second phase will provide for bypassing one-half of the rectifier supplies during flattop. This limits the voltage fluctuation to a value consistent with continuous operation. In the full energy phase, a second transformer will be added and the system kVARs will be reduced by switching precharged capacitors.

A great amount of mechanical energy in modern vehicles and in some other machines is dissipated by the brakes during deceleration. Recuperation of this energy promises great economical advantage. A band mechanism and flywheel allows the recovery of mechanical energy with great efficiency. The main kinematic and dynamic characteristics of the ideal mechanism, and of the actual mechanism with its dissipation of energy, show that this is a mechanism suitable for use in commercial vehicles, excavators and similar machines.

This paper suggests a method of determining the best distribution of mass in the coupler of a 4-bar linkage to approach the desirable condition of constant total kinetic energy. It is felt that, in many cases, this presents a more effective utilisation of mass than the time honoured method of suppressing speed fluctuations at the input shaft by means of an adequate flywheel. Examples are included of the application of this method to a drag-link mechanism and a crank rocker mechanism.

IN the February number of the Geological Magazine, Mr. A. J. Bull illustrates an interesting experiment on a type of deformation in a sheet of elastic material subject to a contraction. The inferences he draws from it, however, need further discussion. An elastic solid, under sufficiently great stress, will develop a permanent deformation either by continuous yield or by fracture, according to the nature of the material. The stress needed to produce such deformation may conveniently be called thestrength. But in certain circumstances it is possible for a stress to produce a considerable change of shape before the strength is reached, and such phenomena are common in engineering practice. A simple example is provided when a rod of india-rubber is compressed longitudinally. So long as the force applied is not too great the rod remains straight; but at a certain critical value of the compression it suddenly buckles sideways into an arc. The straight form is still a possible position of equilibrium, but it is no longer stable, and the slightest disturbance grows until the rod has become strongly bent, giving a new and stable position of equilibrium. It is easy to verify in this case that the strength has not been reached; we need only remove the thrust on the ends, when the rod returns to its original straight form. Another example is provided by a flywheel on a long shaft. Steady rotation is possible at all speeds; but there is a critical speed at which instability develops. Then it becomes possible for the rod to bend and to carry the centre of the flywheel around a circle of finite radius; the tendency of the rod to recover its form provides just enough force to keep the centre of the wheel moving in a circle. Any further increase of the speed of rotation will make the shaft bend through a considerable angle, with disastrous consequences. Other known cases arise in the collapse of tubes under external pressure or longitudinal thrust.1

The measurement of torque under unstable conditions of speed is usually extremely difficult and inaccurate when a dynamometer, prony brake, or similar torque measuring equipment is used. The device described in this paper was developed primarily to obtain torque measurements under unstable conditions as well as under stable conditions, and to obtain a permanent record of these measurements. It has been particularly successful in recording speed-torque curves of motors during acceleration and it can also be applied very effectively to other fields.

In this paper are described some new spinning-tops, gyrostatic apparatus, and illustrations of gyrostatic action devised by the author in the course of the last nine months. The apparatus has been built in the workshops of the Natural Philosophy Institute of the University of Glasgow, and has been employed in illustrating the lectures on rotational motion delivered in the Natural Philosophy classes in the course of the session just closed.Fig. 1 shows a model aeroplane fitted with a small gyrostat in the position of the propeller. The gyrostat is therefore fixed on the front of the aeroplane with the plane of its flywheel at right angles to the length of the machine. The flywheel of the gyrostat, so fitted, represents exactly the rotor of the engine and the propeller of an actual aeroplane.

The measuring element in modern gyrotheodolites is almost exclusively a suspended casing with a flywheel, designed to spin around its horizontal axis. This paper demonstrates the relationships betw...

Rotational systems are often required to maintain steady angular motion with slow velocities. Under these circumstances, sustained torsional oscillations (self-excited) may easily occur, basically caused by the fact that the static coefficient of friction is appreciably higher than the kinetic coefficient of friction. Such oscillations are in-tolerable in a system requiring steady motion. An analytical solution of the system of Fig. 3 is given, which is then put into an analog computer, giving numerical results shown in Figs. 8(a) to 8(f) for various shaft sizes and friction coefficients. It has been possible to assemble all this information in a single dimensionless diagram Fig. 9 which shows the minimum unstable rotational speed of Fig. 8 for values of flywheel inertia, shaft stiffness, friction coefficients and internal damping. It is believed that Fig. 9 will be found useful in the design of slowly rotating shaft systems.

The accuracy of all calculations relating to the hunting of synchronous machines connected mechanically to reciprocating apparatus depends largely upon the correctness with which the value of the synchronizing power P 8 may be determined. Thus, the calculation of flywheels necessary for the parallel operation of engine driven generators depends entirely on a correct value of P 8 . Likewise, the WT R2 which it is necessary to incorporate in the rotors of synchronous motors when driving compressors or pumps can be calculated correctly only when P 8 is accurately known. So far as the author is aware, no attempt at a complete analysis of the subject has been made heretofore. The object of this paper is to develop a method by which the synchronizing power P 8 may be calculated fairly accurately under any condition likely to be met with. The method applies only to synchronous machines of the usual definite pole construction. Blondel's conception of two reactions with some modifications and extensions is followed generally throughout the paper.

The development and operation of a dynamic tire cord testing apparatus is described. The apparatus consists of a rotating wheel which applies a transverse load to a tire cord and carries it to break. It can be operated at speeds which impact tire cord at velocities of from 10 to 80 ft./sec. The techniques used for detecting, recording, and calculating energy load-elongation characteristics and time to break are described. Some data showing the effect of impact velocity on the physical properties of nylon, rayon, and polyester tire cords are presented.

Toy cars propelled by energy stored in flywheels are well known. A rather more sophisticated form of this principle has led to the development of electric locomotives which require neither batteries nor overhead wires or conductor rails. The National Coal Board are interested in the possibilities of this system for underground transport. This article, which describes the construction and operation of an experimental locomotive, is based on a lecture delivered to a joint meeting of the Southern Centre of The Institution and the Southern Branch of The Institution of Mechanical Engineers on the 19th November 1959.

A consideration in detail of electric drive for rolling mills, including classification of mills and motors, mathematical deternminations of energy required for rolling, relation of speed to tonnage, motor capacity and flywheel application.

A high speed tensile tester was designed to study the tensile properties of thin polymer films using a flywheel. The tester consisted of a variable speed motor (1-HP) coupled to a flywheel, tooled from steel disc, through pulleys. It provided tensile speed over the range from 0.1 to 10m/sec. The force arising while testing the sample was detected by means of a semiconductor strain gauge whose output signal was fed to vertical deflection plate of an oscilloscope. The sweep of the oscilloscope was triggered when the light beam to a phototube was traversed by striking-fork mounted on the rim of the flywheel just before stretching the sample. The amplifier of the oscilloscope was flat from DC to 100kc. The resonance frequency of the strain gauge with a clamp for the sample was 1.1kc and its sensitivity was 2.5mV/kg if the carrier voltage was 1V.The response of the high speed tensile tester to the force arising in stretching the sample was examined by means of an analogue computer. The response relates to the true stress, strain, the strain rate, resonance frequency and the damping of the gauge and upper and lower cut-off frequencies of the amplifier recorder system. The motion of the gauge should be represented by the following equation:x+2lx+ω2x=F(t)/Mwhere x is displacement, M is the effective mass of the moving part including the mass of clamp. F(t) is considered stress function which shows load-time relation of the sample. The difference of the observed load-time curve from the true under 1m/sec of tensile speed is shown for various bandwidth of amplifier and resonance frequencies of the gauge. From the results, it is found that the observed load-time curve at 1m/sec of tensile speed is in accord with the true curve if the upper cut-off frequency of an amplifier is 5kc, the lower one is DC and resonance frequency of the gauge is 2kc, and at higher speeds these values increase proportionally except the lower cut-off frequency.Considering the above analysis, stress-strain curves of the commercial film of cellulose-triacetate are indicated at the rates of strain from 200 to 8000%/sec. The results are compared with those of the tests carried out on the same materials with an Instron type tester at the rates of the strain of 0.17, 1.7 and 16.7%/sec.

The methods of analysis and calculations outlined for a small brass-slab rolling mill can be applied to other installations. The time and money spent selecting the proper motor size saves extravagance in first cost, maintenance, and power factor correction.

The problem of calculating the resonance frequency and power pulsation of a synchronous motor direct connected to reciprocating apparatus is comparatively easy, provided the machine is operated from an infinite system, i.e. , a system having constant voltage and frequency. In this paper a method is developed for calculating the resonance frequency of two synchronous machines electrically in parallel. It is also shown that in a system of n machines in parallel, there are ( n - I) resonance frequencies. A general method of calculating these is given. Systems of three and four machines are treated as special examples of the general case. The theory is also given for calculating the actual power pulsations which occur in systems of two and three synchronous machines connected to reciprocating apparatus. With some approximation the theory is extended to four machines and a general method for n machines is suggested. Simple methods of calculating the correct sizes of flywheels necessary for the successful parallel operation of engine-driven generators are given. These are calculated directly from a knowledge of the resonance frequencies involved. In general the thesis is a mathematical treatment of the phenomena which occur in connection with hunting of synchronous machines, electrically in parallel and direct connected to reciprocating apparatus. Specific problems have been treated and illustrative examples presented which make quite clear not only the nature and causes of hunting, but also the methods of overcoming it.

Clutch-brake motor systems are described and advantages inherent in using them in on-off, rapid acceleration industrial control applications are discussed. Clutch-brake motor system equations are discussed and the addition of an energy storage flywheel is considered. Finally, specific industrial applications are described.

The DODGE satellite was launched on July 1, 1967 into a near-synchronous orbit to demonstrate gravity-gradient stabilization at that high altitude and to experiment with various design parameters and damping techniques. This satellite was the first to be three-axis stabilized at high altitude using gravity-gradient techniques. It continues to function satisfactorily to the present date. Stabilization in pitch and roll to better than ±;10 degrees has been obtained. The yaw stabilization of ±45 degrees has been fairly consistent; with the assistance of a small angular momentum flywheel, yaw accuracy of ±20 degrees was achieved. Magnetic damping of the sample-and-hold type and simulated hysteresis were both successful in damping librations. Efforts with the torsion wire suspended damper boom scheme were not successful, probably due to a mechanical bias in the device. A TV camera system permitted observation of the boom bending under the influence of solar heating. Mechanical hysteresis in the boom bending was observed.

Recent innovations in the method of driving roll trains by the induction motor as accompanied by a rotor of considerable inertia effect has compelled the study of a dynamical problem of some complexity. The problem is essentially a commercial one in requiring that the mechanism involved shall exhibit the greatest return on the investment. This unavoidably imposes the consideration of the prime mover as well as the motor and equipment immediately attached to the roll train. While a complete statement of the solution of this commercial problem cannot be evolved at this time, it is the purpose of the following analysis to exhibit the manner of disposition of certain important elements.

In order to perform "time-resolved" photography of long sparks on a strip of film placed inside a flywheel rim, an optical system has been devised based on a nearly concentric mirror-pair similar to that used in a conventional reflecting microscope. A field-flattening lens is used together with two lenses to correct the chromatic defects introduced by the field-flattener. The nominal aperture is f/1.85 with a focal length of 72 mm. Simultaneous photographs of the same discharge are shown taken by a f/4.5 quartz-rocksalt achromat and the system described above. These show the advantage to be gained by using the above system.

The magnitude of the perturbations to the steady-state rotation of most mechanisms is difficult to control with present methods. This paper shows an alternative method of reducing the magnitude of these oscillations. The analysis is carried out for a single slider-crank mechanism found in a tandem compressor. The analysis shows that an order of magnitude reduction in these oscillations is obtainable.

The power system for the ZGS ring magnet consists of a flywheel motor generator set and four groups of mercury arc rectifiers operating alternately as power rectifiers and power inverters. The system is shown schematically in Fig. 1.

THE PROBLEM of automatically maintaining constancy of speed in rotating machinery is frequently encountered, aside from prime-mover governing, in such applications as d-c drives for a-c generators whose frequency must be kept unvarying to a high degree of accuracy for signalling purposes or for exacting test-floor operation. To satisfy the need for a means of effecting such speed regulation, an electrical governor has been developed and an analytical study has been made of the requirements for stable control of the governed system.

The characteristics and level of the noise emitted by stationary diesel engines of the type used in power houses are considered. With gas sources adequately silenced the spectrum of the noise of the automotive engine has a pronounced peak in the frequency range 1000–2000 c/s whereas the larger stationary engine shows a peak at a much lower frequency. Most notable among the constructional differences are the exposed flywheel and in many cases panelled crankcase; the significance of these design features is discussed. The authors have attempted to isolate the various noise sources: combustion and mechanical (particularly piston slap). The contributions to the total noise of the individual outer surfaces, such as crankcase frame, flywheel, cylinder head and various covers and panels, are also discussed in detail.

Notwithstanding the rery large rated capacity of the 45,000-kv-a. generators for the Queenston power house of the Hydro-Electric Power Commission of Ontario, their essential construction features are not different from those of much smaller rated generators. The generators are of the certical shaft type with two guide bearings, and a thrust bearing. The thrust bearing is located above the stator arid carries the weight of the complete rotating elements of the generator and water turbine. Each generator is provided with a direct-connected exciter. The flywheel effect required for satisfactory speed regulation of the turbines necessitated the use of auxiliary flywheels mounted on the shaft adjacent to the generator rotor. The rotor is constructed with a number of cast steel wheels which together form the rotor spider for carrying the pole pieces. The pole pieces are made of punchings and are attached to the rotor with three dovetails per pole. The coils are made of copper strip wound on edge. The stator frame is split vertically into three sections to conform with foundry and shipping limitations but the core is built up without being split. The stator windings consist of form-wound, diamond-shaped coils, cach slot containing two coil sides. The coils are made of stranded conductor and are insulated with mica tape, which affords more or less flexibile insulation.

As the nuclear research laboratory is supplied with numerous lethal equipments, adequate safety measures are imperative. Another important consideration for such laboratories is flexibility of the power system as changes are so frequently necessary. Some of the specific requirements of both utility and research power are discussed.

Simplicity and reliability have been kept foremost in generators recently developed for Diesel-electric switcher locomotives ranging from ten to 80 tons. New motors and control equipment have been developed at the same time. This paper deals especially with the generators, their electrical and mechanical features, and performance characteristics, both as power generators and as motors for engine starting from the locomotive battery. Operating fundamentally as self-excited generators, separate exciters have been eliminated. The simplicity of the generator windings has allowed corresponding simplicity of control circuits.

A rapid graphical method is devised to estimate the natural frequencies of a multicylinder engine with flywheel and accessory drive on opposite ends. This method is valid, provided that the inertia loads contributed by all cylinders are equal and the torsional stiffness between the cranks does not vary. The accuracy of the values of natural frequencies can be improved by a simple iteration procedure.

The estimating of the power required to drive rolling mills is largely a matter of experience and the use of tests carried out on mills as similar as possible, but the paper gives a few formulae which have been employed for this purpose. In mills where the load fluctuates considerably, flywheels are desirable and the use of these is discussed, together with the mechanical arrangements of the drives. Several types of variable-speed non-reversing drives are described, together with the limitations of each system. For very wide speed variations and for the larger reversing-mill equipments the use of Ward-Leonard or Ilgner control is essential. A description of a large equipment, together with details of the necessary control gear, is given, arious alternative details being discussed. Various methods of improving the power factor in rolling-mill electric drives are then considered. Owing to the importance of the auxiliaries for rolling mills, a section is devoted to this question, together with descriptions of new devices. The drives referred to in the paper are in general those for mills to roll iron and steel products, but the particulars are applicable in most cases to drives for mills rolling non-ferrous materials.

An analytic study of flywheel autopilots for attitude control of space vehicles is described, and the results of a three-axis analog computer program are presented. The objectives of this study were to determine the requirements, capabilities and limitations of flywheel autopilots as functions of desired accuracy and speed of response, disturbing moments, differential gravity restoring torques, component uncertainties, and vehicle initial attitude and attitude rate errors. The stability and accuracy degradations that resulted from not compensating for gyroscopic crosscoupling torques are summarized. Design tools are presented for synthesizing a three-axis autopilot in accordance with specified design criteria of size, power, accuracy, response rate and error disturbances.

The negative-inertia mechanism consists of a double-worm drive with a small flywheel attached to the output shaft. By connecting the drive in parallel with the servo load, very high deceleration rates can be obtained. The drive thus effectively cancels most of the load inertia, as long as the load is decelerated. During acceleration, the drive adds slightly to the original load inertia. Characteristic design equations of the system are described, and experimental results presented. The drive is intended mainly for velocity servos, where very high decelerating torques are required without using clutch-brake mechanisms or excessively large servomotors.