In order to develop a vibration monitoring system which detects a transverse crack in a rotating shaft system, it is necessary to clarify the vibration characteristics of a cracked shaft. In this paper, we investigated the influence of a crack on the resonance phenomena at the secondary critical speed where a natural frequency is equal to double the rotating speed. The followings are clarified: (a) when a crack appears in a horizontal rotating shaft, a whirling motion of the forward precession whose frequency is double the rotating speed appears, (b) the amplitude depends remarkably on the angular position of the unbalance relative to the crack, (c) this phenomenon is explained clearly if the spring characteristics are expressed by rotating nonlinearity.

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The fluidelastic vibration of a tube array caused by cross flow has been studied with a correspondence to a physical image. It is shown that an unstable vibration caused by a negative damping fluid force can be computed on the assumption that the unsteady fluid force acting on a tube in a tube array is calculated by the combination between the movement of the tube and the separation point along the tube surface, which is based on a visualized test. The boundary of the instability shows a reasonable coincidence with the other published data.

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The previous report discussed the lasting longitudinal vibration of a bogie car, which was the 1st modal one excited by the vertical track irregularities. The present paper describes analytical results of the effects of the rubber stiffness on the longitudinal vibration characteristics. The rubber used for fixing the primary damper is a sort of vibration isolator acting in series with the damper, and its stiffness has to be lowered in order to allow the damper to incline with the horizontal distance between the truck frame and the axle box. However, when the stiffness is too low, the damping effect deteriorates. In the realistic range of lowered stiffness, the 1st modal longitudinal vibration grows with the lowered stiffness, and when the stiffness is lowered further, the vibration due to the truck pitching increases markedly.

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This paper deals with the characteristics of unstable self-excited vibrations of a rectangular, flexible weir installed in a tank, over which water in the upstream tank discharges into the down-stream one. Experiments were carried out for measuring the vibrational strains of the weir, and the oscillation of the water surface in the up-stream tank with changing inlet velocity of water and discharge height. We examined the vibration characteristics of the weir with changing tank ratio (defined as the down stream tank length/the upstream tank length), and found that the occurrence of unstable vibration depends strongly on the tank ratio. The phase relations of the weir vibration to the upstream tank water oscillation were experimentally investigated.

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An analysis is presented for the free vibration of angle-ply laminated circular cylindrical thick shells having any combinations of boundary conditions. For this purpose, the maximum strain and kinetic energies of the shell are evaluated analytically according to the first-order shear deformation theory (FSDT), and the frequency equation is derived by minimizing the Lagrange functional with respect to unknown coefficients of the displacement functions. These displacement functions are written in the power series which satisfy any combination of the geometrical boundary conditions automatically. In numerical examples, the natural frequencies and the mode shapes of the angle-ply laminated thick circular cylindrical shells are calculated, and the effects of the lamination parameters (fiber orientation, number of layers) and the boundary conditions on the Vibration are studied.

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Abnormal unsteady vibrations, apparently different from normal vibrations of the piping system around reciprocating pumps, have been experienced in the suction piping system of a reciprocating pump at a petrochemical plant. Results of measurements of the piping vibrations and pressure pulsations show that (1) the abnormal vibrations are caused by the unsteady pressure pulsations; (2) the unsteady pressure pulsations are classified into two typical types; and (3) the unsteady pressure pulsations are deeply related to the existence of vapor or gases in the piping system. Installation of a volume bottle with precharged nitrogen gas is effective in preventing the abnormal vibrations.

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One of the significant vibration sources producing higher frequency noises in refrigerant compressors used for air conditioners or refrigerators is the reed valve which controls the refrigerant gas flow from the discharge port. In order to reveal the higher-frequency vibrations of the reed valve coupled with the compressed gas flow, we conduct a vibration test for an axisymmetrical simple model composed of the valve, the valve plate, the cylinder and the piston. First, compressed air is led into the flow chamber through a capillary tube at the piston center, and the valve is excited to induce a forced vibration in a frequency range from 50 to 500 Hz, Then, the fluid pressure in the flow chamber is measured for different cylinder volumes to determine the amplitude and the phase-lag relative to the valve vibration, thus resulting in a flow-induced vibration criterion for the reed valve. Secondly, a free vibration test of the reed valve is performed to verify that the reed valve actually induces a self-excited vibration when the vibration criterion obtained from the forced vibration test is satisfied. Finally, the fluid force determining the vibration frequency of the reed valve and the level of fluid excitation is examined.

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Although it is known that active dynamic absorbers are useful for controlling the vibration of structures, the design method for popular usage has not yet been established. This paper proposes the design method of the active dynamic absorber by the use of the LQ optimum control theory. First, nondimensional representations of the state space formulation of the structure and active dynamic absorber system, the state feedback gain matrix, and the weight matrix are constructed to obtain a generality. Secondly, the relationship between the vibration control effect and parameters of the weight matrix are clarified for designing. The design data are prepared as the nondimensional root locus, the frequency response, and the impulse response charts. The effectiveness of the active dynamic absorber designed through this method is demonstrated experimentally.

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A new dynamic absorber system using the lever and pendulum mechanism is proposed for controlling the displacement of high-rise structures due to wind or earthquakes. Due to the effect of the lever and pendulum mechanism, the displacement of the dynamic absorber can be several times less than that of an ordinary dynamic absorber, and the spring can be designed easily from the point of view of its strength. Also, due to the effect of the virtual mass by this mechanism, the natural period of this system can be lengthened without using a soft spring, and the damping can be made several times higher than that of an ordinary dynamic absorber.

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There is no single use of the FEM for the problems including unbounded domains because they require countless elements. Thus some combination methods of FEM and analytical solutions have been investigated. In most of them, a single artificial boundary such as a circle is assumed, and analytical solutions are used for the area outside of the artificial boundary. Nevertheless, in problems such as of a wave scattered by several objects, many elements are required to fill the space within the artificial boundary. If the artificial boundaries enclosing the individual objects can be assumed, the number of finite elements can be reduced. This paper deals with a method based on this idea for treating acoustic waves in two dimensions scattered by several objects.

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It is assumed that small sized moving machine is available in the field of biomechanics and chemical reaction, etc. If we construct an equipment using traditional electric motor as a power souce and wheels as a driving element, it is difficult to keep the size within the permitted limit. So we must investigate a new type system. In this report, we constructed an equipment which is driven with the force of inertia produced on viblating a piston of linear type actuator as a trial. Using this equipment, experiments on the performance was conducted and comparison between experimental data and specification was made. The results have shown that the driving performances are in approximate agreement with the specification. But the moving action at the lower speed becomes unstable owing to the frictional loss of the piston. The inverstigation on how far the infiuence extends by this loss is a topic for the future study.

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Experimental study of a pipe inside mover which is made from a piezoelectric element is presented. It can travel inside a small diameter pipe, and has a function of forward and backward movement. Fundamental performances, i.e., the relationships among its velocity, power supply voltage, power supply frequency and tractive force are examined.

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The "drive by wire concept" is the most promising means for a control system of the automobile engine power train in the near future. In this concept system, the accelerator pedal is not connected by a mechanical "cable" or "linkage" but connected with the throttle valve by an electrical "wire". With an adaptation of the concept system, several useful controls such as traction control, fuel optimal control and cruising control are expected to become possible. Reported here is the improvement of automobile acceleration performance using the control theory called exact model matching method or model following method under a background of the concept. Experiments were carried out using a sham "automobile" system constructed with a 4-cycle gasoline engine, automatic transmission and DC dynamometer which were connected with an on-line computer system for measurement and control. The expected results were obtained both theoretically and experimentally.

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In this study, the optimization problem of dynamical characteristic of vibration controllers for mechanical structures subjected to such a nonstationary input as seismic wave is dealt with. A simple optimization technique based upon the stationary design and the modal analysis is presented. In order to take into account the nonstationary influence in the response, the stationary criterion is modified in each mode by the ratio of the response variance of each mode to the square of the response spectrum: By applying this technique to the optimization problem of the allocation and the dynamical characteristics of a dynamical vibration absorber for a piping system, its usefulness is verified.

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This paper describes a vibrationless access control which eliminates endpoint vibration of a positioning mechanism with multi-degree-of-vibration-freedom. The proposed access control is composed of four vibrationless acceleration control regions, two constant acceleration regions and one constant velocity region. Arbitrary access strokes can be realized by changing the periods of constant acceleration regions and the constant velocity region. Minimum energy vibrationless control input and corresponding motion trajectory are theoretically derived. The validity of the proposed access control is demonstrated with computer simulation results and experimental results. A combined control of control point velocity tracking feedback together with feedforward control is recommended in an actual application. New velocity tracking feedback control is also proposed, which is equivalent to the combination of feedforward and feedback control and is effective in suppressing vibration under a low feedback gain condition.

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Number and dimensional syntheses of an adjustable mechanism with two timevariable inputs and one path-pattern-variable input have been presented in the former paper, by considering the working space input torques and joint forces under unit load. In this paper, the point-to-point control of a manipulator which consists of the above mechanism is studied from the viewpoints of optimizing the operating time and the energy consumption of driving source. Moreover, above manipulator is compared with the manipulator with three degrees of freedom, and the dynamic characteristics of the system are analyzed theoretically and investigated experimentally.

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As an available method to precisely control the temperature of the outer pool of a bomb calorimeter, a method using electric heaters is considered. The operating characteristics are experimentally investigated and compared with those of the Nenken-style method using hot water. The heaters are long and fine in shape and are uniformly set in the pool. They are subject to a digital control law composed of a time-scheduled control and a finite-time settling control. It is consequently confirmed that the heaters can be superior to the hot water method in controllability, accuracy in controlling, uniformity in heating, and ease in setting up. Also, it is found that this system provides the outer pool with far better follow-up characteristics to the inner one on temperature than the existing Nenken-style automatic calorimeter.

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For a control method of bending-torsion-coupled vibration of a rotating plate, a control mechanism using trapezoid tendon mechanism is presented in this study. The proposed tendon mechanism consists of two control sticks driven through tendons individually driven by motors at two points of the plate. This mechanism is modelled by applying the Lagrange's equation and an optimal control system is constructed by the optimal control theory. In order to investigate the control characteristics of the tendon control system, computer simulations and control experiments were carried out for 5 kinds of geometry and 4 installation points of the control sticks. As a result, the usefulness of this control method was demonstrated and the optimal conditions about the geometry and the position of control sticks were made clear.

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In the previous papers, we reported the motion control methods and experimental results on the parallel bicycle which is composed of the double inverted pendulum-type body pivoted on the axis of the parallel wheels and the double controlling arm suspended from the upper end of the body. The inverted pendulum-type parallel bicycle can be well stabilized and travels according to the servo reference by using the controlling arms or the wheels. However, it cannot be adapted to uneven paths such as stairs. In order to travel uneven paths, we have developed the new type of the parallel bicycle with an articulated joint which connects the bodies divided in two pieces. The bicycle can change its configuration by folding its body and adapt itself to environment or application. The control methods and experimental results on the new vehicle are described in detail in this paper.

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In this paper, we present the feedback control of a one-link flexible arm having reduction gear friction. Tip position control was very difficult in the case of large friction treated as an equivalent viscous friction. Experiments showed that tip position. feedback control was possible by using the dither signal. We investigated the influence of the dither amplitude on linearizing the nonlinear friction and the response of feedback control. The acceleration signal from the accelometer at the arm tip, like the signal from the strain gauge at the arm root, could use feedback control for the fundamental vibration mode.

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The active vibration control of a steel cantilever beam with a piezoelectric ceramic actuator is presented. The actuator is bonded near the fixed end; the beam-actuator system acts as a monomorph mechanism. The control is the IMSC (independent modal-space control) based on the modal displacement estimation by the modal filter with an OP amplifier. The first mode is estimated with three modeled modes using two non-contact displacement sensors. The modal velocity is estimated with the Kalmam filter. The optimal regulator and relay controls were implemented with a personal computer. The relay controls yielded faster decay, since the actuator output can be applied more effectively. The linear velocity feedback was used instead of the dead zone, then the amplitude at the free end decayed to 1μm in 0.7 sec, when the initial amplitude was 1.0mm.

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Recently Yano proposed a new theory of muscle contraction, termed the electrostatic linear actuator model. Base on this theory, we developed an electrostatic linear actuator as a biomimicking skeletal muscle. The fundamental actuator unit consists of a parallel plate capacitor and a slider made of dielectric material. Based on this model, we derived the 70 theoretical formula for the thrust of the actuator. This formula revealed the following facts: The thrust can be maintained constant when the supply voltage is kept constant, and can be remarkably increased by optimizing the dielectric constant of the fluid which fills the space of the capacitor. Using this formula, we designed a simple practical model expected to generate the thrust of 10mN with the stroke of 10mm. The surface area of this actuator was 1cm².

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This paper deals with the newly developed robot 'O-jiro (One-legged jigging robot)' which realized stilts-walking. The impact of stepping by two legs disturbs the balance of the body, so this robot has a vertical arc-shaped plate as a leg. The one motor swings the leg cyclically, so the supporting point moves from side to side like a stepping of stilts-walking. As the same time, the other motor drives the rotor equipped the top of the body to turn the lifted leg toward the direction in which the body leans (forward or backward), So the O-jiro can keep stable. Thus he can realize the stilts-walking stably with a simple mechanism and only two actuators. As a result of the experiments, he could keep standing stably, and it is confirmed that the usefulness of this mechanism as a locomotive robot.

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This paper deals with a compensation method of deflecting flexble structures handled by a robot manipulator under gravity. A simplfied model of vibrating flexible structure is proposed in this paper, and the parameters necessary for the compensation control are identified by the extended Kalman filter. The compensation angle is estimated based on these identification data. The compensation control is carried out both by the simulations and experiments. In particular the vibration control is considered on the simulations of compensation control. Comparing these compensation results with each other, we show this compensation method is useful under the assumption that the deflection is small.

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Flexibility and torque ripples in the joint driving system produce vibratory behavior in the motion of a robot arm. This decreases the quality and efficiency of tasks executed by a robot arm. This paper examines three kinds of vibration control methods using acceleration feedback from the viewpoint of the closed loop eigenvalues and time responses. The angle of departure of the eigenvalue loci with respect to acceleration feedback is also discussed. It is shown from control experiments and theoretical analysis that the simple control method using only one accelerometer gives satisfactory results for the SCARA-type arm.

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Nonlinear dynamic compensation, which is derived from inverse dynamics, is very useful for controlling robot manipulators. An accurate modeling of the robot system and a precise estimation of the physical parameters, however, are necessary in order to get enough control performance with that method. In this paper, on the mathematical model of robot manipulator with PD controller, the stiffness of the transmission system between motor and robot arm is taken into consideration. Furthermore, the controller parameters are adjusted only by using actual motor angles and reference robot arm angles. The effectiveness of this method is examined by an experiment using an industrial SCARA robot. The result proves that this method provides satisfactory performance for a reduction of both residual vibration and tracking errors.

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A travelling wave-type ultrasonic motor is one of the promising motors for robot arms since it has a simple construction, a high response, and large torque at low speed. The rotational direction of the rotor can be changed when the direction of the travelling wave is reversed. This paper proposes a rotational speed control method by changing the duty ratio of the reverse-direction duration using PWM(Pulse Width Modulation). The basic characteristics of the ultrasonic motor using this velocity control were examined experimentally. It was confirmed that the rotational speed of the ultrasonic motor decreased with the increase of the duty ratio of the reverse-direction duration and the linearity between two variables was almost satisfactory, even in an open loop control.

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This paper presents a full three-dimensional dynamic modeling method of spatial robotic manipulators with flexible links and revolute clearance joints. The system dynamic equations using a Denavit-Hartenberg notation and Component Mode Synthesis are effectively utilized in the dynamic modeling method. The development of the contact force model for revolute clearance joint is explained in detail. The numerical analysis of a 2-link manipulator based on the modeling reveals that the joint clearance significantly deteriorates the positioning accuracy of the manipulator and increases the bearing forces at the joint.

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This paper describes a system which enables fast 3-dimensional measurement of a human head by means of a slit-ray projection method. The system developed here consists of a laser slit-ray projector, two CCD TV cameras, a real-time video signal processor and a 16-bit computer. Due to the employment of this real-time video signal processor and a fast data-processing technique for using a look-up table, a 3-dimensional measurement of the human head can be accomplished in 4.3 seconds, and all the image data are converted to 3-dimensional data in 1 second. Experimental data reveal the applicability of our system.

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This paper presents a method for measuring the correct impact force acting on the top of a short bar. In this method, the impact force is calculated from the stress detected by the strain gauge at one point on the short bar. The theory of this measuring method based on the theory of propagation of longitudinal elastic stress wave is very simple. It is confirmed by the impact test that this measuring method is suitable in practical use. This method can be applied to the measurement of force in the range from impact to quasi-static force.

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The Joetsu Shinkansen Line running through a heavy snowfall district is installed with a snow-melting system whose function is to melt snow deposited on the railway tracks by sprinkling heated water over the total length of the line within the limits of Niigata Prefecture. Because of its long water path, in these systems, delivery and return of the water takes a very long time, resulting in a time lag as the feedback control characteristics. In order to improve this control, a control system using a feed forward algorithm has been developed and a system operation test has been carried out in a field. It is found very promising as a snow-melting system from the viewpoint of energy saving since the control cycle time is cut down by following the changes in weather conditions such as snowfall, atmospheric temperature, and wind velocity.

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In this paper a method for collision-free trajectory planning along specified paths of two manipulators in a common workspace is presented. One of two manipulators is designated to be the master and the other the slave by giving motion priority. The motion of the master is constrained by limitations of input torques/forces and that of the slave by limitations of input toques/forces and collision-free conditions. The dynamic equation of the manipulator is expressed by the path parameter 's' which does not depend on time. The quantity λ(s) which connects the time t and the path parameter 's' is introduced. Optimizations of λ(s)'s for minimizations of travelling times are carried out by the dynamic programming for the master and the slave. Finally, the proposed method is applied to two manipulators with two links. Numerical result of the example shows the effectiveness of the method.

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Japanese safety law requires robot safety precautions to be taken in such way that the gate to the robot operation zone cannot be opened unless the plug is removed and the removal of the plug cuts power to the robot. However, in reality, this safety measure cannot be employed if high operation efficiency is required. Safety systems for robots are considered here by taking an example of the robotic seesaw working system, in which the operator works with the robot by moving his working location to another in the robot zone. In this paper, to secure safety against the risk of collision between the robot and human operator involved in the conventional seesaw working systems, firstly, the logical construction for the safety operation system is presented, considering coordination with robot. Secondly, the fail-safe interlocking system is proposed for robotic seesaw operation, which is expected to secure safety and improve productivity. Lastly indicated are the methods for the realization of sensors for the fail-safe interloking system.

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A goal programming formulation in the optimal design of structures is proposed to find a practical solution although all design constraints are not strictly satisfied. The method treats design constraints and objective as goals, and tries to find a feasible solution that achieves the goals as well as possible. A goal level of achievement is introduced to settle multiple criterion. Moreover, in some problems, the number of iterations excessively increases although goal programming formulation is used. The relaxation of the unachievable goal levels is incorporated to hasten the convergence. As examples, a rod with a point mass and a beam with a point mass are optimized in consideration of several types of design goals related to eigenfrequencies, the total mass, and design variables.

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This paper deals with an optimum design problem for beams subject to a moving load. The optimum design is classified into two types of problems. The first problem is a nonlinear optimization with discrete design variables, and the second one is the optimization with continuous variables. The optimization procedures consist of the dynamic programming with discrete variables and the penalty function method with continuous ones. The procedures are combined to a sequential form and applied to the problem. The optimum shapes of beams are obtained with the constraint of the conservation of total mass.

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Wheel flats, caused by the braking of rolling stock, give rise not only to vibration and noise of vehicles but also to mechanical damage to bearings and axels. The actual conditions of wheel flat occurrence were investigated for commuter trains running on main lines by means of a wheel skid detector newly developed by the authors. Places and times at which wheel skids frequently happened on a JR line were clarified as a result of the investigation. The phenomenon and mechanism of wheels being locked by electric braking were discussed as major factors for flat occurrence. The decrease in adhesion between rails and wheels at such locations was evaluated under various climatic conditions.

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It has become very important to improve hydraulic motor efficency, especially in the starting and low-speed ranges, for finer hydraulic operation. From this point of view, this report aimed to provide technical data to help improve a swashplate-type axial piston motor's performance, particularly concerning the friction characteristics of a ball joint. The effects on its friction characteristics are experimentally examined with regard to swashplate angle, supply pressure, surface roughness, and friction coefficient, etc. The results show that the friction moment of a ball joint is almost never affected by the piston phase angle, and oil temperature, but depends heavily on supply pressure, and that the friction moment strongly affects oil film thickness and leakage flow.

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Improvement of the efficiency of hydraulic motors is very important issue, especially in the starting and low-speed range, for finer hydraulic operation. From this point of view, this report aimed to provide technical data to help improve the swashplate-type axial piston motor performance, particularly in terms of friction, leakage characteristics and oil film thickness between the valve plate and cylinder. The effects on these characteristics are examined with regard to supply pressure, rotational speed, and static force balance. The following results were obtained: (1) friction torque between the valve plate and cylinder is almost never affected by rotational speed or piston phase angle, but strongly depends on supply pressure and static force balance; (2) leakage flow rate is affected by supply pressure, rotational speed and static force balance.

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It is very important for a cable puller to grasp a wire rope tightly without any slippage and with no damage on both of the rope surface and cable gripper. The friction mechanism of a wire rope under a large deformation due to high grasp force, however, has not been sufficiently clarified. The present paper will report some results on friction of the wire rope under high compressive load on some cases such as under lubricated condition and under different contact conditions using three types of wire rope with steel core, fiber core and a galvanized rope with fiber core. As the results, the difference of contact area between the wire rope and gripper greatly affects the friction behavior; that is, the gripper with a curved surface can bring large friction force comparing with the gripper with a flat surface owing to its large real contact area, which is dominated by a restriction of the escape of wire between gripper surfaces and the deformation of a rope and a core.

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In view of the fact that lubrication in metal forming processes often differs from one workpiece material to another with other conditions being the same, experiments on strip drawing are carried out with mild steel, commercially pure copper and commercially pure aluminum as workpiece materials and a paraffinic oil as a lubricant. Theoretical analysis is also carried out by taking account of heat generation due to friction at the tool-workpiece interface. Since this analysis includes not only the yield stress but also the heat conductivity of the workpiece material, the effect of the workpiece material on temperature rise and hence on the friction coefficient can be calculated. It is thus shown, both experimentally and theoretically, that the friction coefficient for aluminum is smaller than that for both mild steel and copper. This is due to the fact that the yield stress is smaller and the heat conductivity is larger for the former than for the latter two. It is also shown that the friction coefficient increases with increasing thickness reduction, while it appears to decrease when the surface roughness of the workpiece is larger.

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The contact angle between the ball and thread groove in ball screws changes following the Hertzian contact deformation and elastic deformation of the thread. Hence, how the contact angle changes with the axial load is calculated, and the effect of it both on load distribution in the screw thread and on axial stiffness is examined for the single nut and the preloaded double nut. An increase in contact angle of some 2° is calculated under basic dynamic load rating. The nonuniformity of load distribution is not influenced by the contact angle change. However, the normal load of a ball at a contact point between the ball and thread groove decreases slightly. The axial stiffness of the ball screws, consequently, rises as the contact angle increases. The measured values of axial displacement are in approximate agreement with the calculated results.

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Water leakage rate through packed gland was measured to determine how total packing height, packing compressive stress and fluid pressure affect the leakage rate in stugffing-box seals. Two types of packing rings, asbestos and graphite, were tested at room temperature. It was found that the leakage rate can be described by the theory of leakage through porous packing and/or clearance between packing and side walls. An experimental equation to describe the sealing capability of packing has been determined as a function of packing compressive stress and fluid pressure.

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A simplified method for numerical calculation of the traction in partial elastohydrodynamic lubrication (EHL) was proposed. There was a clear difference between the calculated results of the rheology model and the experimental results in partial EHL, the rheology model is an effective method for numerical calculation of the traction in full EHL. In this paper, a successful method for numerical calculation of the traction in partial EHL was proposed. The points of this method are very simple, and express the partial EHL traction coefficient by two factors of asperity interactions and full EHL actions. We used this method for numerical calculation and obtained satisfactory results, and could explain the effect which the surface roughness and difference between line and point contact condition exerted.

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In recent years, engine oils have contained various kinds of additives such as high molecular-weight polymers to improve their performance. Such lubricants exhibit viscoelastic behavior, but the lubricants were assumed to be Newtonian fluids in most of the previous investigations on piston ring lubrication. The objective of this paper is to theoretically clarify the effect of nonlinear viscoelasticity of lubricants on piston ring lubrication by introducing a nonlinear four-element viscoelastic model which consists of two nonlinear dashpots and two nonlinear springs. Numerical solutions show that the effect of viscoelasticity reduced the frictional force and the film thickness. In addition, the phase of the variations of the frictional force and the film thickness of viscoelastic fluids is delayed compared with that of Newtonian fluids.

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Scoring-proof ability and frictional characteristics of oils containing solid lubricants such as molybdenum disulfide and graphite, a S-P type EP additive and organomolybdenum compounds such as MoDTP and MoDTC were evaluated by using a two-roller machine under a step load condition. In the case of the addition of molybdenum disulfide or graphite, scoring load and frictional conditions, such as coefficient of friction, surface temperature and the state of oil-film formation, were similar to those of the base oil in which those additives were not added. The addition of the S-P type EP additive and the organomolybdenum compounds improved the scoring limits. These improvements can be attributed to the formation of substances which inhibit the occurrence of scoring. The substance is insulating and has a high coefficient of friction in the case of the S-P type EP additive, while that is conductive and has a low coefficient of friction in the case of organomolybdenum compounds. Two diagrams of surface temperature-friction coefficient and insulating voltage-friction coefficient clarified the effects of these additives.

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Diesel rail cars in Japan have played a major role in transportation on mountainous lines. However, their efficiency of current transmission is low and their running speed is slow, because they run by hydraulic stage of current transmission. The authors built a new transmission system equipped with two direct stages of claw clutch. The transmission was tested in RTRI, JR. Recently, they built two transmission systems improved upon a previous transmission with reference to the test result. The transmissions were installed in a standard diesel railcar of JR. and tested on a mountainous main line of JR after a test in RTRI, JR. The test result was satisfactory. The running efficiency of diesel rail cars will be improved greatly thyough the adoption of this transmission.

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In the case of CVT (Continuously Variable Transmission), employing 3 K-type planetary gears, being manufactured, the speed of the output shaft of the CVT can be changed continuously from zero up to high speed. In this report, the construction of automatic transmission (RX-AT) has been designed incorporating this CVT, and the normal force has been set to make RX-AT transmit the power without slippage. After the equation of the rating life was determined by the experiments, the size of the RX-AT was determined by this equation and the normal force. Furthermore, from the result of manufacturing the experimental model RX-AT, a RX-AT more compact than conventional automatic transmission has been realized.

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The thermal deformation of machine tool spindles has recently become the most important problem to materialize the manufacturing system for the product with higher accuracy and performance. In order to solve such problems, a large number of investigatioins so far has been dealt with reducing the thermal deformation of the spindle mainly caused by internal heat sources such as bearings. However, there is no effective model to express the dynamic and thermal behavior of the spindle bearing system in actual rotational condition. In this paper, therefore, to establish the dynamic simulation model of thermal characteristics in machine tool spindle systems with the rolling bearing, the thermal closed-loop concept of the thermal behavior of machine tool spindles has been proposed. The validity of the proposed model has also been verified through experimental investigations under various rotational conditions. In addition, the thermal behavior and effectiveness of the high-speed spindle adapter have been investigated using the proposed model.

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The thermal deformation of the machine tool spindle mainly caused by the internal heat sources such as a bearing has recently become the most important subject to enhance the performance of manufacturing systems for precision prouducts. In this paper, the dynamic thermal hehavior of the main spindle system with the rolling bearing have been simulated on the basis of the thermal closed-loop concept and also using the finite element method. Especially in the constrained condition of the spindle nose, which causes in the variation of heat generation in the bearing because of the transient thermal deformation of structural elements, the effects of the bearing surroundings, i. e., those of the quill and bearing housing structures, fave been clarified. Comparing the obtained results with experimental ones so far reported elsewhere, the validity of this simulation has also been verified. In addition, the thermal and mechanical effects of the reinforcing rib in the spindle housing and also the cooling effects of the quill have been investigated by the proposed method.

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One specific feature of the aerodynamic sound produced at the face end region is that the radiation becomes weak by filling root spaces as equivalent as by shorten center distance. However, one can easily expect that such action make the air flow faster, and consequently make the sound louder. This paper tries to reveal the reason for such feature. At first, air flow induced by the pumping action of the gear pair was analyzed regarding series of root spaces as volume varying cavities which has channels to adjacent cavities as well as the exit/inlet at face ends. The numerical analysis was verified by the hot wire anemometer measurement. Next, from the obtained flow response, sound source is estimated to be a combination of symmetrically distributed simple sources. Taking the effect of either center distance or root filling into consideration, it has become clear that the simplified model can explain such feature rationally.

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