To prevent the failures like scuffing and pitting on tooth surface, it is necessary to decrease the flash temperature and tangential force that are proportional to friction coefficient. And to decrease the power loss of power transmission gears, it is necessary to estimate friction coefficient at tooth meshing surface. But there was no formula with high accuracy for estimation of friction coefficient under mixed lubrication condition considered a ratio of surface roughness and oil film thickness. In this paper, empirical validation of the new estimation formula of friction coefficient was carried out. In the contact zone under mixed lubrication, a combination of fluid friction and boundary friction exists. The new function of load ratio expressed as a simple function of the ratio of surface roughness and elastohydrodynamic lubrication minimum oil film thickness was verified. To evaluate the formula, two disc tests were conducted. The estimated values agreed well with the experimental results. The friction coefficient can be estimated by using the new function of load ratio constructed by the maximum height surface roughness.

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This paper describes about a planetary roller type traction drive for high speed motor, which features a new self-loading mechanism to achieve bi-directional drive and high partial load efficiency. The ring roller is elastically and polygonally deformed along contact points, and the circumferential length thereof changes with the arrangement of pinion rollers. In case of four pinions type, the ring roller deforms from square to rectangular when two opposite pinion rollers rotate in the circumferential direction. Since the circumferential length of the rectangular is shorter than that of the square, the contact force can be decreased. When two opposite pinion rollers rotate 20 degrees, the contact force can be changed 45%. The test results prove that the partial load efficiency can be improved comparing with the constant loading mechanism.

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This paper shows the dynamic characteristics of traction drive integrated drive generator "T-IDG" and prediction method of them with showing the comparison between test results and simulation results. The simulation analysis of traction drive CVT has proved that the dynamic performance of T-IDG is affected not only by the geometric design and rotational speed as traditional theory but by the inertia, stiffness and other mechanical or hydraulic factors of T-IDG. The hydraulic control system of T-IDG based on this simulation analysis can help keeping the rotational speed of generator within MIL-STD-704 allowable limit against steep change of load.

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The simulation of rolling contact fatigue strength of traction drive elements was proposed. It can account for both the distribution of sizes of inclusions in the element material and the influence of traction forces at the element surface. In this study, the influence of crowning radius on the rolling contact fatigue strength was examined by using this simulation. To consider the effect of crowning radius, the simulated imaginary roller was changed to the multilayered one. Because of the increase of the number of large inclusions with increasing critical volume, the calculations using this improved simulation resulted in the decrease of rolling contact fatigue strength with the increasing crowning radius.

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In the research of a gear, it was mainly surveyed when defect or extraordinary phenomena was found out. Therefore, the research data studying a gear which was operated for long period under stable condition was rare. In terms of extending maximum life-span, we liked to take a hint to predict a life expectancy from good status of use. We made a detailed observation by TEM, focusing on the structure under sliding surfaces of final drive gear in an automobile transmission, which was used in a real driving car for approx 300,000 km. As a result, it was found that the grain sizes were very fine in the subsurface area down to 0.3μm, and cracks, which cannot be seen from the surface, were present.

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This paper describes a synthesis of a spatial parallel link mechanism for heliostat which drives a reflection mirror to track moving sun and to reflect sun light to concentrator at the top of the central tower in thermosolar power plant. By considering dustproof and maintenance performances, 3-RUU mechanism is adopted with type synthesis. Inverse kinematics is then achieved by solving a system of nonlinear equations with 18 variables. Based on the inverse kinematics, dimensions of the mechanism are determined so as to maximize its workspace on three posture angles. Several simulations reveal that the synthesized mechanism can track sun almost in whole year.

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In this study, effective use of exhaust heat as one of the way saving energy of vessels is described. Recent years, the depletion of fossil fuels, air pollution by exhaust gas has become a serious problem. Therefore, the technologies about fuel saving and effective use of energy are required. Vessels also use fossil fuel as an energy source. Large vessels generate steam in the exhaust gas economizer by using the exhaust heat of the main engine. This steam is used for heating fuel, heating the room and hot water supply in the vessel. But, recovery of exhaust heat of the main engine is not enough. If it is possible to generate electric power using the low-pressure steam, that can contribute to energy saving of vessels. Therefore, prototype steam engine for generation using low-pressure steam was developed. This new steam engine is use the end cam which is newly devised as a motion conversion mechanism. This new cam called "Crown Cam". In this paper, first, prototype steam engine is introduced for the principle and structure. Secondary, this steam engine is introduced for the design and configuration. Finally, prototype steam engine was produced.

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The compressor can be classified a dynamic type and a positive displacement type. In the case of the high discharge pressure, the axial flow compressors are used without the pulsatory motion. While, the reciprocating compressors that one of the positive displacement type have the advantage of the higher discharge pressure. A slider-crank mechanism used in a reciprocating compressor is valuable to convert mutually between the linear and rotational motions. However, there is a problem about friction loss and the vibration caused by the force reacting on the piston from the cylinder side wall, during the piston stroke. This phenomenon shortens the lifetime of the compressor. The side force prevents the driving with the high velocity revolution, so a field of use is limited. When the reciprocating compressor can be driven with the high velocity revolution without the vibration and pulsatory motion, a new type of the compressor is realized to transport the air with high discharge pressure and the large volume. This type of compressor is expected to be applied to the field of manufacturing and welfare. In this paper, we try to design in order to eliminate the side force from the compressor, to realize the low vibration compressor using a orthogonal double-slider joint mechanism. We structured the kinematic model and verified the characteristics of the compressor analytically.

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This paper shows a design of the leg motion generating mechanism of a wearable walking assist machine for hemiplegia. Four types of the mechanism in which two revolute joints each with a mechanical brake and one prismatic actuator are employed, were shown. Five states of the leg during the transfer phase were obtained through measurement of walking by healthy persons, and reference joint angles for each state have been determined. Through kinematic design and dynamic simulation, feasibility of stable waling using the proposed assist mechanism was shown.

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In recent years, the needs of machine maintenance have led to demands of remote diagnostic techniques for gear-teeth. Different maintenance methods have been developed to diagnose damage to the gear-tooth surface using different techniques involving, for example, acoustic emission, sound, tooth root strain and vibration. However, for early detection of gear-tooth abnormalities, such diagnostic methods are not optimum. If the damaged tooth can be detected, it is difficult to grasp the damaged area on the tooth surface in detail. To address this problem, we developed a method that uses a laser beam. This method is as follows: A tooth surface is irradiated by the zonal laser beam from an oblique direction, and then the irradiated laser beam line is shifted along the surface of the tooth according to gear rotation. If the damage on the irradiated tooth surface exists, the output voltage proportional to reflection increases. In gear fatigue testing, we measured the gear by using the above-mentioned method. Then we found that owing to the increase of number of cycles, the output voltage proportional to reflection changes. Because teeth surface property are transformed every second by gear engagement. Nevertheless, we have not elucidated how roughness of tooth plane, displacement of tooth flank form, et cetera affect the output voltage. It has to be clarified to improve accuracy and apply this method. Therefore, in process of growing pitting fatigue we got the output voltage, roughness of tooth plane and tooth form error and investigated relationships by experimentation. In conclusion, we have the relation of three factors.

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Conventional measurement of cylindrical gears is carried out only on working tooth flanks based on the principle of the generating method, and tooth profiles and pitch deviations are separately measured. Those measuring procedures have essentially disadvantage in measuring time due to additional movement for tooth indexing. New measuring strategy proposed here has the advantage to overcome such long-time consuming measurement because the measurement strategy is to scan whole circumference of a cylindrical gear outline including working flanks, tooth tip, root and bottom profiles without detaching the stylus tip from the gear surface. It can be done with two axis movement: the first axis is stylus movement in radial direction and the second axis is the rotational motion of the gear measured. The synchronized movement control of both axes is the key to achieve the constant line speed scanning in whole measurement. A standard cylindrical gear was measured using the developed GMM and the whole shape of the gear outline was successfully obtained with the scanning speed of 5mm/s. The tip edge is one of the challenging shapes to be measured, but it was also obtained in good accuracy by adjusting the nominal data to be used. The proposed method has the great advantage because the measured whole data have information of tooth profiles of both flanks of all teeth, tip diameter, the edge shapes of tooth tips, root and bottom profiles of all teeth, as well as pitch deviations.

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Measurement, monitoring and control are very important in precision machining technology. In order to increase the accuracy of the measurement system; application of camera or vision is very essential. Automatic control is also vital for the measurement performance to be improved. During measurement of the gear profile; human monitoring sometimes may face danger as the stylus is very small and thin as well as the probe moves with a maximum speed of 10mm/s. At this speed if accident happen to the machine then there is high possibility to break the stylus tips and scatter everywhere and its even danger to human eyes. Thus, human monitoring is necessary during measurement for checking the performance of the system. This paper presents the successful implementation of the vision system in precision engineering which saves time and increases safety of the measurement system.

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The high precision gears are strongly required for advanced motion and power transmission. And the improved evaluation technology for the precision gears is becoming indispensable. Moreover, the reliability of the measured value became important when the accuracy of the gear becomes high, and the establishment of the traceability system has been needed. For the establishment of the traceability system, the higher precision gear measuring machine (GMM) with lower uncertainty is expected to improve gear calibration uncertainty. For the purpose, we proposed a new concept of the high precision GMM from analyzing the problems of the conventional GMM, and we have developed a prototype of the high precision GMM using the direct drive mechanism. Then, the high measurement capability of the developed GMM was verified by the evaluation method using the gear artifacts such as involute, helix and pitch artifact. On the other hand, some new methods conducting GMM accuracy evaluation using simple shapes such as sphere and plane have been proposed as standards. Therefore, we tried a new evaluation method for tooth profile measurement using a sphere artifact whose sphere was treated as the tooth flank, and the high measurement capability of the developed GMM was verified by a new evaluation method. This paper describes about the evaluation results of the developed GMM for tooth profile measurement using sphere artifacts and discusses the effectiveness of the sphere artifact as a new artifact.

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The fluid motion around mesh region might interfere or assist the lubricant delivery to the tooth surfaces for heat removal. For better cooling of gear teeth immediately after mesh, fluid motion was investigated experimentally. The matter of interest concerns rather high speed operation of about some tens of meter per second. Visualization was done in air with smoke, and also in water with transparent PMMA gears and tank in which plastic and metallic tracer particles were used. By several means of 3-D visualization, whole behavior of fluid movement was discovered; Some part travels before pitch point trapped in back lash space, some part is sucked into tooth spaces axially from the leading end opening and some part gets into the space from the mesh exit space with some axial velocity component. Afterwards movement of particles is discussed for practical lubrication from the exit region of meshing. Since the small particles are driven by drag force of fluid, the movement depends on the projection area of the particle and also on weight (inertia), the heavier the weight the smaller the driven effect. This revealed that the experiment in water corresponds to the actual condition when the lubricant forms misty, or the size of the particle is small enough. Additionally some hints for better delivery is proposed such as bigger oil drop is preferable when traveling in air.

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Micropitting, which is one form of fatigue damage, can lead to serious breakage if it progresses. In this study, I examined two lubricants that differ in their micropitting characteristics, and investigated the influence of the boundary lubrication film by analyzing the surface shape and the chemical forms on the tooth flank. The micropitting test was carried out using the FZG gear test machine (DIN51354). From the test results, the number of smoothed areas was greater on the tooth surface which micropitted area was smaller. And the smoothed area was softer than other area. According to XPS analysis, the main ingredient of the boundary lubrication film was iron phosphate and iron oxide. A higher ratio of iron phosphate film was found in the deeper on the softer tooth surface. Blending the lubricant with an additive agent to form a flexible iron phosphate film prevented the generation of micropitting on the tooth surface.

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This study discussed about the initiation of the failure of driven shaft and also proposed an effective technique to reduce the moments applied onto the driving shaft of monorail for forest industry. At first, geometrical change of the tooth was observed after the rack rail was used for about 200 hours (employed for about 30days) at civil engineering construction site. The power unit of monorail was driven with traction on the original and worn rack rail in the short range at laboratory. The variation of torsional and bending moment applied onto the driven shaft were measured with respect to the rotational angle of the shaft when the driven gears were engaged with original and worn rack rail, respectively. To reduce the wear of the rack rail, pitch diameter of pins in which number of pins was also reduced was decreased in comparison with that of conventional gears. The results showed that a reduction of 73% in average torsional moment applied onto the driven shaft of the front gear was obtained. Shear sliding on the surface of the rack rail tooth was prevented while by applying the modified gear. In conclusion, to decrease pitch diameter of pins in which number of pins was also reduced to prevent the failure of driven shaft of monorail for forest industry was effective.

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Due to the advantages of smooth transmission, great transmission torque and low axial force, herringbone gears replace spur gears to construct the planetary gear set of the transmission system of the wind turbine. It is a reality that the variable speed process exists in the transmission system of the variable-speed constant-frequency wind turbine, so in this paper, a dynamic model for herringbone planetary gears is proposed which can be applied in the dynamic analysis of variable speed or large velocity fluctuation process. The planetary gear set is transformed into parallel-axis external and internal herringbone gear pairs in the moving coordinate system to obtain the meshing forces, then the Newton's law in non-inertial coordinate system is utilized to obtain the equations of motion of planetary gears. The dynamic responses of start process of planetary Gears in wind turbine are analyzed and the effect of the profile error excitation on the dynamic response is also investigated.

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Influence of alignment error and manufacturing error in face gear engagement is reported. Although many face gears are used for the fishing spinning reel, the time required for adjustment during the assembling of a reel has been increasing when the tooth flank is not modified. According to this report, it was shown when a tooth flank modification with transmission error (TE) controlled curve was applied to a manufactured tooth flank, and the influence of alignment error has been decreased. In a mass production, however, it is also necessary to take into account manufacturing error of a pinion gear and a face gear in addition to alignment error. In this research, those factors of manufacturing error were considered in the assembly error. The factor effect analysis was conducted by 3D simulation. On the other hand, it is well known that there are two types of interference, namely, "interference of tooth tip" and "interference of tooth root" on face gear engagement. Those interferences occur when a face gear and a pinion gear are in contact on the pitch circle (reference position). Through this research, a new type of interference was discovered, which comes from the impact of both an alignment and manufacturing error. Therefore, tooth flank modification with TE controlled curve needs to take into account this new type of interference. In this report, the actual sample was measured in the combination of an alignment and manufacturing error and the existence of this new type of interference were actually confirmed.

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This paper presents the results of measurement and analysis of exciting force by mesh of gear for the purpose of figuring out the generating mechanism of the force. The equipment that measures the exciting force with a unit of helical gear by force sensors arranged to the spindle was developed. There was verticality force to a line of action observing the Lissajous' figure measured exciting force. Assuming that the force was frictional force, the verification examination was carried out by the spur gear that was simple of mesh. Comparing the prediction with measurement results, it has proved that the force has occurred by friction. And it is shown good correlation between measurement and analysis friction force.

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The purpose of this study was to develop a approximation method of tooth stiffness of gear pairs in numerical calculation of gear system vibration. Tooth stiffness is approximated by fourth order function based on the transmission error. Firstly, the validity of the approximation applied to Multi Body Simulation was confirmed by comparison with Tooth Contact Analysis about the transmission error and the tooth bearing. Secondary, Multi Body Simulation with the approximation applied to simulation of gear noise variation on transmission assembly including bearing clearance. The proposed method allowed the prediction of the variation tendency of the vibration due to changes in bearing clearance.

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On parallel gear system, we have proposed that mesh excitation is constant having no concerning with operating speed under constant load condition. And the characteristics became the basis of estimation method of mesh excitation with vibration measurement result. In this research, we investigate vibration characteristics like that with planetary gear system.

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We tried to diagnose the surface failure on the gear tooth using the synchronous averaging method. The vibration signal was emphasized with the synchronous averaging method to reduce a noise. The signal was subdivided into every one pitch of gear to detect the surface failure on the gear tooth. The subdivided waveform of the vibration signal was to evaluate by the maximum amplitude and the standard deviation of the waveform. As a result, it was demonstrated that the synchronous averaging method is effective in the diagnosis of the surface failure on the gear tooth, and can identify the tooth with the surface failure.

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This paper deals with nonlinear vibration caused by parametric excitation in gears, namely, the gear rattle of helical gear system and the parametric excitation of multi-step gear system. These systems are studied by approximate method and the numerical analysis which is called shooting method. As a result, the followings were made clear. (1) In the gear rattle, because of the interaction of the torque variation, the tooth profile error, and the mesh stiffness variation, large amplitude vibrations occur in low frequency region and the higher-harmonic resonances also generate. (2) In multi-step gear system, not only primary and secondary parametric excitation but also many types of parametric excitations such as combination parametric excitation generate, because of the characteristic of multi-degree-of-freedom system with the mesh stiffness variations.

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At the beginning and the end of cutting in cutting machine, impulsive vibration and noise break out due to the gear backlash. For protecting the vibration, the brake method is used. That is, optional brake unit is installed to the work axis of the machine for teeth to establish contact (one-side no-backlash condition). We offer the paradox-gear method. One sub-gear with less tooth number by 1 than the drive main-gear is added on drive axis with free rotation and in mesh with work gear (paradox-gears). The main and sub-gears are pressed each other through brake shoe and spring, one-side no-backlash gearing is realized. By this method the mechanism is simpler and the energy loss is far smaller than the brake method. About the theory and practice of the paradox gear method will be presented here.

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The power losses of spur gear drive change with the gear rotation speed. When gears rotate at a high speed, churning loss occupies the large part of the power loss in the gear drive. In this study, we investigated the effects of the driving conditions on the churning loss of gear drive. In the experiment, the churning losses of spur gears with three kinds of modules were measured in oil bath lubrication. Then, we discussed the effects of lubricating oil and gear speed on the churning loss. As a result of this study, it is found that the oil viscosity has an influence on churning loss except using traction oil, high gear speed provides large churning torque, and large module of the gear has large churning torque.

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In this paper, we evaluated the difference in the grease of a small sized geared motor, which was kind and kinematic viscosity of base oil and cone penetration. The result shows that, the loss at no loading depends on the cone penetration and the kinematic viscosity of base oil. Load depending part, the friction loss of gear mesh not depends on the cone penetration and the kinematic viscosity of base oil. The mean friction coefficient of a tooth flank by grease lubrication proved the constant value that mineral base oil type was 0.09 to 0.11, and synthetic base oil type was 0.07 to 0.08.

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This paper describes a study on the quantitative measurement of oil film thickness in the oil impregnated sintered porous bearing by the ultrasonic method. Where, the ultrasonic method means to detect the reflected ultrasonic wave amplitude for the oil film thickness measurement. At previous studies, it was shown that the quantitative measurement of oil film thickness in the oil impregnated sintered porous bearing with inner diameter 10mm and 3mm is possible. In this study, we made it possible to measure the distribution of the oil film thickness in the oil impregnated sintered porous bearing by measuring the oil film thickness in the two orthogonal axis.

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