XML has vast potential to facilitate the transformation and exchange of design data. Since XML is structured that users can define their own tags and attributes, it has characteristics as both document and data container. XML is platform-independent and easy to transform into different formats. These characteristics of XML facilitate integrating various forms of engineering design data in the distributed engineering design environment. In this research, we have developed a web-based design system that integrates gear design data in the form of XML. The system generates the Gear XML documents from gear design data determined through design activities. It also transforms gear design data in the database into Gear XML documents automatically. The Gear XML documents can be showed not only in the form of XML but also in the more visible format of HTML, transformed by the XSLT document developed. They are also transmitted to Gear Modeler Agent through SOAP, and then the agent is automatically executed and finally generates CAD model files and VRML files. The designer can check the generated VRML model immediately in the integrated web service.

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Representation of design information is essentially needed in the collaborative design on the distributed design environment. In this paper, a methodology how to share the design information of a gear drive design using Extensible Markup Language (XML) is proposed. XML is the standard web language of the next generation and can be used as a neutral format shared by various design applications. Since XML is a platform-independent meta-markup language, it is possible that standardization of technical terminologies and reduction of additional programming efforts between web based design applications in the collaborative design. To show this advantages, we developed a gear drive XML application that will be used in the collaborative design of gear drives in web environment. This gear drive XML application is a markup-language that can represent the design information of machine elements (gears, shafts, keys and bearings) composing gear drives. Data Type Definition (DTD) for gear drives is also developed. The XML DTD for the gear drive design is divided into structure and semantics. The DTD structure is composed of dimensional information, material information and so on. For the DTD semantics, dimensional design terminologies are made according to the International Organization for Standardization (ISO) standards.

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Within the last fifteen years the maximum transmitted power of one gear pair in mesh has increased from 65 MW to nearly 150 MW. Modern gear technology in design and manufacturing has made this possible. New aspects came up with this development, especially with regard to material and the safety requirements. Furthermore even a high efficiency of gears in this power range produces a remarkable amount of power loss. Therefore additional effort to reduce power loss pays off very quickly. Several means were investigated and the power loss could be reduced drastically to about half of its original value. Thus energy savings of several hundred kilowatts were realised. The presentation gives major aspects and practical exsamples of a resonable number of gears in service.

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An experimental comparison of face-milled and face-hobbed spiral bevel gears was accomplished. The two differently manufactured spiral bevel gear types were tested in a closed-loop facility at NASA Glenn Research Center. Strain, vibration, and noise testing were completed at various levels of rotational speed and load. Tests were conducted from static (slow-roll) to 12600 rpm and up to 269 Nm (2380 in.lb) pinion speed and load conditions. The tests indicated that the maximum stress recorded at the root locations had nearly the same values, however the stress distribution was different from the toe to the heel. Also, the alternating stress measured was higher for the face-milled pinion than that attained for the face-hobbed pinion (larger minimum stress). The noise and vibration results indicated that the levels measured for the face-hobbed components were less than those attained for the face-milled gears teste

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Developed is the design and production system of the conical involute gear, which is composed of gear cutting method, gear grinding method, over-ball measurement for control of finishing dimensions, tooth surface measurement, tooth surface analysis, and the design of a pair of gears. As a result, the conical involute gears came to be used in a wide range of applications. This paper presents a systematic research and development of the conical involute gear for 25 years and its practical applications used in many mchines.

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DNK series standard gear reducers introduced in this paper use point-line meshing cylindrical gears, which are made of through hardening steels and the cutting by hobbling and with a common quality grade. The load capacity of these reducers is higher, the noise levels are obvious lower, the procedure of gears manufacturing is simpler and the price is lower. The development of DNK reducers has made the research of point-line meshing gears reaching a new development stage. It has made this technique to be really and widely in use in industry.

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This paper describes design and performance of external gear pumps with the tooth profile based on cycloid tooth profile. We developed the method to accurately calculate the displacement volume of external gear pump to apply non- involute tooth profile as well as involute tooth profile. Using this method, we calculated the displacement volume of external gear pump with involute tooth profile, cycloid tooth profile, involute- cycloid composite tooth profile, and modified cycloid tooth profile. Then, we discussed merits and demerits of these tooth profiles on the displacement volume. In addition, we made a gear pump with involute- cycloid composite tooth profile, and the displacement volume of the pump was measured. Consequently, it was confirmed from both the calculated and the experimental results that the displacement volume of the gear pump with involute- cycloid composite tooth profile is about 20% larger than that of the conventional gear pump with involute tooth profile.

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The movable tooth gear drives are categorized as those with movable tooth on their gear blank. There are two major kinds of movable tooth gear drive, one with local degrees of freedom gear tooth or the positions of the movable teeth relative to the gear blank (carrier) remains unchanged, and the other with revolute joint or sliding gear tooth. The first kind may be considered as an evolution from their predecessor of pin cycloildal gear drives and the second kind from their predecessor of harmonic gear drives. Because there are one or more moving pairs in movable tooth gear drives, the topological constructions can vary greatly. Many research works have been done in China since 1980's and a lot of new mechanisms for the movable constructions are patented [1]. In this paper, we summarized the characteristics of the conceptual developments of movable tooth gear drives and generate the atlas graph for the movable tooth gear drive. Two groups of design components are described in the paper, they are sleeve tooth gear drive, ball cycloid gear drive, sliding tooth gear drive, swing tooth gear drive and variable speed ratio movable tooth gear mechanism.

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In process of gear power transmitters design, constructor is faced with well and badly structured problems. In the first case, it's easy to make mathematical model and to apply it. On other occasion, problem is very complex, and mathematical model can't be easily and effectively made. Solution for the problem of badly structured problems is in use of fuzzy logic. This paper presents an example for the use of fuzzy logic in gear power transmitters design. Determining the teeth number for small gear is being made by use of fuzzy expert system..

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In this paper, the mechanism of metal-belt continuously variable transmission (CVT) in the transitional state is analyzed. The acceleration signal of the CVT system in vehicle transmission test rig is picked up when the system is in operation under different condition. The vibration characteristic of the CVT system in the transitional states is investigated online by the means of three-dimension waterfall at constant interval. The distributing rule in frequency domain and relationship between the speed change ratio and torque are obtained. The method and results obtained from the study are significant to theory and practice.

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This paper presents a CVT line pressure control strategy for the increased shift speed. Firstly, simplified dynamic models of the line pressure and the ratio control valve are derived by considering the CVT shift dynamics and low level control algorithms are suggested based on the dynamic models. In addition, shift speed maps are constructed. Using the speed ratio maps and the simplified dynamic models of the CVT system, shift performance is investigated. It is found from the experimental and simulation results that improved shift speed can be achieved by increasing the line pressure.

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The slip characteristic is one of the most important characteristics of metal-belt continuously variable transmission (CVT), which affects the accuracy of transmission ratio. In this paper, a new method for measuring slip ratio of CVT is presented. By measuring axial displacement of primary pulley cylinder, rotary speed of the primary and secondary pulley of the CVT system, the value of slip ratio of the CVT is got indirectly. The principle of the measuring method has been analysed. The influence of accuracy of displacement sensor on accuracy of the slip measurement is analysed, and the relation between fitting accuracy of transmission ratio and fitting method is investigated. A test rig of vehicle transmission with the CVT is built to carry out the measuring of the slip ratio of the CVT under the condition of different input torque, different input rotary speed, and different pressure in secondary pulley cylinder. The results of the study are analysed and the practicability of the measuring method is proved.

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To study fuzzy control strategy of the autopilot system for the CVT vehicle, the simple autopilot system and the CVT car model on a chassis dynamometer test bench are established in this paper. Considering the highly nonlinear multiple-input-multiple-output coupling system of CVT system, and various driving condition and complex external resistance disturbance, the fuzzy-PI control algorithm of parameters self-tuning is employed in the throttle controller, and the hybrid fuzzy-PID control algorithm is adopted in the engine speed controller. The results of simulation show that the adaptive fuzzy control strategy of autopilot system employed in this paper is effective and feasible, it has practicability.

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In order to study the dynamic characteristics of automobile with CVT system, a bond graph analysis model of continuously variable transmission is established in this paper. On the base of the simulation state space equations that are established by the authors with bond graph theory, a fuzzy control strategy with expert system of starting process has been introduced in this paper. Considering uncertain system parameters and exterior resistance disturbing, the effect of the profile of membership function and the defuzzification algorithm on the capacity of fuzzy controller has been studied. The result of simulation show that the fuzzy controller proposed in this paper is effective and feasible. It has been employed in the actual control and has practicability. The study lays a foundation for design of the fuzzy controller for automobile with CVT system.

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The influences of lubricants on the torque capacity and transmission efficiency were evaluated by using the commercial CVT unit. Furthermore, in order to analyze the friction characteristics of each contact parts of CVT, a block on disk type friction testing machine was created. As a results, it is found that the maximum torque capacity between the belt and pulley in actual CVT correlated with the friction coefficient under high contact pressure (150MPa) and relatively high sliding speed (0.1 m/s) by the friction test. The measurements of the transmission efficiency of CVT were conducted by varying the thrust force of the secondary pulley and speed ratio with steady oil temperature. The efficiency of transmission decreased under the condition of multiplying speed side at a lower load. The maximum difference of the efficiency among all tested oils reached up to 4%.

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Continuously variable transmissions, CVT's, are used where the stepless change of torque and/or speed is necessary. While this kind of transmission was first used only in general industrial drive assemblies, nowadays almost all car producers worldwide are providing passenger cars preferably with embracing-CVT's. Through the employment of CVT's, benefits like increased driving comfort, reduced noise emission and fuel consumption can be obtained in comparison to conventional manual or automatic transmissions. Considering the demands of costs, lightweight and performance the comparative testing of load capacity of the available CVT-systems on the market, built with embracing organs, gives the transmission developers helpful information. In continuous work a test rig based on the principle of power circulation was developed at the FZG in order to test the load capacity of continuously variable embracing-transmissions. The mechanic and hydraulic function of the test rig, the construction of three variator systems (embracing organs, sheaves) and the test method are described. The results of constant load tests in three different working points of the variator by variation of the load are discussed. In this connection a differentiation of the damages, - breakage of the chains/belt and scuffing on the sheaves -, is shown. Basing on the test results of constant load tests woehler diagrams and the results of multiple load tests of one embracing organ are presented. The results are part of an extensive research project realized at the FZG in order of the Forschungsvereinigung Antriebstechnik e. V. (FVA) [1] and a valuable basis for further development of variator systems.

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A model and criteria for the jumping limit torque of roller chain drives are presented. The following parameters are considered : chain and sprocket geometry, chain and tooth stiffness, shaft stiffness, chain weight and initial tension. Friction is important in separating jumping on DriveR and DriveN sprockets since the jumping behaviour is different at the two sides. The model is developed for symmetrical catenary and no dynamical effects. Experiments on jumping are scarce in literature, so extensive experimental results are presented and compared with calculated ones. Agreement is good for 1 : 1 speed ratio where jumping always occurs on DriveN sprocket. In a speed down drive jumping may shift to DriveR sprocket. The shift takes place around speed ratio 1 : 3. A good prediction requires wthat asymmetrical catenaries and dynamical effects are considered as well.

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The present analysis addresses rubber V-belt variators. Experimental results on the elasto-reological properties of several belts are presented and the belt wedging into the pulley groove under static loading is analyzed. The convenience of innovative tensioning strategies is considered, e. g. attaining limit tension and full slip simultaneously, and an approximate formulation for the mechanics of V-belts is proposed. Possible split-way arrangements are analyzed, aiming at the optimization of the variator class.

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In this paper, thrust equations for a rubber belt CVT are derived by considering the geometry and mechanism of the mechanical actuators. In order to solve the thrust equations, an algorithm to calculate the speed ratio is suggested for the given driver speed and load torque based on the actuator characteristic equations and existing formula for the belt thrust forces. Experiments are performed to investigate the driver speed-load torque-speed ratio characteristics at a steady state. The speed and torque efficiencies are measured and are used to modify the actuator equations. It is found that the modified equations predict well the steady state characteristics. In addition, a rubber belt CVT shift dynamic model is derived experimentally. Simulation results of the CVT shift dynamics are in good accordance with the experiments and it is noted that different coefficient is required to describe the CVT shift dynamics for the upshift and the downshift.

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This paper is concerned with noise generation mechanisms of a dry hybrid belt for CVT systems. The dry hybrid belt has been developed and used in CVT systems in sub-compact cars. The system without lubrication and hydraulic apparatus has very high transmission efficiency, which improves mileage. The higher fuel consumption efficiency has been attained in comparison with manual transmissions. Furthermore, the system responses very quickly and does not take up large space in the engine design. The hybrid belt consists of a pair of tension members inserted to many lateral H-shaped blocks. Since the hybrid structure is completely different from those of conventional rubber V-belts, the mechanism of noise generation is also very unique. In this study, some noise mechanisms will be elucidated experimentally using belts with different dimensional parameters and by means of strain measurement of the blocks on running.

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This paper considers measurements of engagement forces between a synchronous belt and a inlet cam shaft pulley of a running engine as well as frictional work simulations where a recently reported belt stiffness reduction is taken into account. Frictional work is closely connected to belt life in terms of wear failures. The measurements show that the pitch difference (pulley pitch minus belt pitch) seriously alters the magnitude of the engagement forces under the working conditions of a running engine. The measured belt force shows small discrepancies due to dissimilar pitch difference. The measurements are also used to verify a load distribution model, previously presented by the author. The results from this model shows good agreement with the measured engagement forces and the model is used in the frictional work simulations. These simulations indicates that the belt stiffness reduction shifts the optimum belt durability pitch difference to a higher value. Further investigations are necessary to establish a method to derive this optimum pith difference.

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Timing belts differ both from their tooth profiles (trapezoidal, curved, etc.. ) but also from their shapes along width (spur, spur stepwise, helical, etc.. ). In addition, meshing of timing belts differ as some of timing belts are pressed on tips of pulley teeth while others are pressed in tooth roots of pulley. Therefore, constant optimization requirements ask for careful comparisons of performances of such timing belts. In this paper, one trapezoidal tooth profile will be considered with an initial pitch of 10 millimeters and different shapes along width such as spur, spur stepwise, circular will be tested. A test procedure was also defined with dynamic transmission error and noise measurements, dynamic torques and efficiency as well as temperature measurements. Tests were performed on an original test rig, sensor devices and data acquisitions will be also described. Further, results will be synthesized for all the timing belts in order to make comparisons. Finally, a discussion will allow us to make relations between design parameter influences and physical phenomena.

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New developments in the automotive timing belt drives have led to the use of automatic tensioner in order to reduce the span tension variations and therefore to increase the belt durability. The objective of this work is to predict and analyze the dynamic behavior of the entire timing belt drive studied versus the running time, the crankshaft instantaneous speed and the camshaft torque. A non-linear model has been developed which describes instantaneous pulley rotations, belt span tensions and the tensioner pulley arm rotation. The timing belt drive is composed of three pulleys and a spring-loaded tensioner pulley with dry friction. The tensioner is modeled with an equivalent measured viscous damping coefficient and a rotational spring stiffness. A test rig has been designed in order to measure the rotational stiffness and the damping of the pulley tensioner. The model has already been validated by experiments in the case of an idler instead of an automatic belt tensioner. First simulations were performed with no viscous damping coefficient for the tensioner. Damping has been introduced in the tensioner model in a second time. The calculation results allow to identify the pulley tensioner effects when compared to those obtained with and idler instead of the tensioner. Belt span tensions, pulley speeds, and pulley transmission errors are studied. The tensioner pivot position in the timing belt drive lay out is analyzed versus the tensioner effectiveness. Numerical results show how the tension fluctuations in the tight span can reduce by changing the tensioner pivot position. A parametric study has been performed on the behavior of the pulley tensioner by making varying the rotational stiffness, the viscous damping coefficient, the pulley mass and the crankshaft speed. Finally, some design rules for timing belt layout with automatic tensioner can be deduced in order to optimize the behavior of the drive.

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In a serial printer, the printing is carried out line by line, while the print-head moves on papers or other print media. The positioning accuracy in moving time of the carriage, in which the print-head is mounted on, influences the picture quality of printing image directly. Usually, the carriage of serial printer uses a stepping-motor as driving source, and it is driven through meshing transmission elements : a couple of reduction gears and a couple of synchronous belt and pulley. Sometimes density non-uniformity is generated in the printing image, which is called jitter and is a main cause decreasing the picture quality of printing image. It has been found that the positioning error by the meshing vibration of synchronous belt is the most significant factor causing jitter.. In this paper, an theoretical analysis for the motion and vibration of the carriage system is provided, and the vibration displacement of the carriage due to the meshing vibration of synchronous belt, namely the dynamic transmission error, is discussed. The theoretical analysis is confirmed with calculations and experiments.

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FEM analysis is a useful method to discuss the deformation and failure phenomena for synchronous belts. In this study, stress and strain behavior in synchronous belts is analyzed by using a general nonlinear FEM program. The calculated results are compared with some experimental data that are measured under constant and fluctuating torque conditions. The difference between these conditions is reasonably simulated by using the FEM analysis.

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Fatigue failure of synchronous belts is investigated under fluctuating torque conditions because the driving torque fluctuates in the automotive engine camshaft drive-systems. Two modes of fatigue failure are observed. The first mode is debonding along the interfaces between stranded glass filaments in cords. The initiation of the debonding is explained by the cyclic bending deformation when the belt is wound around pulleys and transmits the power. A simplified mechanical model is proposed to explain the failure mechanism. The second mode is tooth root cracking on the opposite side of the working flank. The shearing stress at the tooth root is discussed caring out the finite element analysis.

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Synchronous belts are used for a cum shaft drive of automobile by the advantage of their superior synchronous characteristic. These belts are one of the fiber reinforced rubber (FRR) composite materials. That is to say, they are constructed from rubber, facing fabrics and helical cords. Especially, the helical cords keep the extensional strength of the belts. It is known that the helical cords get easily damaged by a bending fatigue around pulleys when the belts are driven. Moreover, the extensional strength decreases with an increase in driving time. This phenomenon is known through experience and is one of the most important problems in the practical use. In this paper, the reduction of extensional strength in helical cords because of the bending fatigue, which is related to the tensile member breakage, was investigated with some experiments, FEM analysis and mechanical analysis. Firstly, we observed the fatigue failure morphology of belt-cords, and confirmed that the de-bonding is initiated and extended at the interface between stranded glass filaments. Moreover, we obtained the result that the extensional strength was reduced as a consequence of the bending fatigue. Secondly, the stress distributions on the cross section of cords were analyzed by using a three-dimensional FEM. The FEM results have shown that the stress of fibers increases with the initiation of the de-bonding. Moreover, it was confirmed that the reduction of tensile strength could be explained by the initiation and extension of the de-bonding. Finally, a simplified mechanical model was proposed to explain the reduction of extensional strength of cords. The analytical results had a good correlation with the FEM and experimental results.

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Synchronous belt drives are widely used in various machines in order to transmit rotation accurately and synchronously. At this time, idlers are commonly used to increase the angle of contact on the pulley and to avoid obstacles. However, the generating source of the transmission error under a transmission force with an idler remains unclear. In the present study, transmission error over a period of one pitch of the pulley was investigated both theoretically and experimentally for a synchronous belt drive with an idler attached when a transmission force acted on the belt span. The experimental results agree closely with the computed results. The magnitude of transmission error was found to vary with a change in the angle of contact on the pulley caused by variation in the idler position. There is an idler position at which transmission error is minimized. In addition, transmission error is reduced when the helix angle is increased.

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The purpose of this study is to investigate the effect of misalignment on traction coefficient in case of crossed axle type traction drive. The measurements of traction force were performed using small size experimental apparatus, (average roller diameter is 50 mm, rotational speed of driving roller is 90 rpm) And the comparison of experimental with calculations of the two dimensional thermal non-Newtonian elasto-hydrodynamic lubrication was performed. Following conclusions were obtained (1) Maximum traction coefficient in this test is 0.1〜0.13. There is no difference between the traction drives and conventional parallel type traction drives. (2) Traction coefficient becomes large by increase of either contact force or misalignment. (3) The measured results are compared to the calculation and it was confirmed that the calculation method is practical and useful.

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This paper deals with the evaluation of characteristics of traction grease. Especially, the comparison with the base oil and the performance at the low temperature are focused. Firstly, we designed and manufactured the two disks testing machine for measuring the traction curve, which is the fundamental data of traction grease and oil. For precise measurement, some equipments and measured data management, i. e., correcting the loss torque of bearings and calculating a traction coefficient were improved. The measured maximum traction coefficient of the traction grease is approximately 0.11 in room temperature. In the range of maximum Hertzian pressure 0.8-2.8 GPa, the Hertzian stress does not influence to the traction coefficient. In the case of low temperature the traction coefficient decreases according as temperature drops. It falls to less than 0.06 over the experimental range 263-293 K. The coefficient of traction oil tends to decrease largely comparing with the that of traction grease.

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This paper discusses the study of a traction drive transmission that uses a wedge action by creating input and output axes that are eccentric. Contact force is acquired in proportion to transmitted torque. Although, this eccentric structure is simple in design, it creates a different traction coefficient at each traction contact point. In order to design a structure that does not incur gross slippage, we need to examine the traction contact point where the traction coefficient is at its highest value. This paper further reveals the traction contact point value at its highest traction coefficient. This is accomplished by analyzing numerical expressions representing the balance of force equation from the viewpoint that a traction coefficient is automatically adjusted. Finally, this paper presents an example of an actual design and test results that show basic characteristics, efficiency, and wedge action in transmitting power. Our test results demonstrate that the traction drive transmission developed through our research achieves high efficiency through wedge action and realizes sufficient contact force in proportion to transmitted torque.

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A half-toroidal continuously variable transmission (CVT) was developed for the first time anywhere in the world for application to passenger cars equipped with a 3.0-liter turbocharged engine. This paper describes several key technologies to establish the system of Dual Cavity Half-Toroidal CVT. Important system technologies are as follows. Traction drive analysis for practical condition, synchronization of 4 power rollers, stability and response of a ratio changing. Traction drive analysis is important to design the loading force of the variator. The traction characteristics were obtained quantitatively over a wide range of conditions by using a 4-roller tester. A mathematical model was developed to calculate traction characteristics, taking into account spin and side slip. The calculated results obtained that temperature has a significant effect on traction characteristics under actual usage conditions. Synchronization of 4 power rollers is important to keep a system reliability. In the variator, the upper and lower linkages of the trunnions are both coupled longitudinally to secure sufficient stiffness and strength for perfect synchronization of 4 power rollers. Ratio change control is important to realize a excellent driveability of the vehicle. Ratio control system, which uses a servo control mechanism with ratio control cam, can realize the quick response and stability at the same time. This paper explains the ratio control system with simulation results and experimental data.

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In November 1999, the first vehicle with a traction drive CVT was manufactured and introduced to the market. The continuously variable transmission (CVT) changes speed ratio by using sideslip, which is generated by a small offset in the Y direction at the rolling contact point. The speed ratio changing mechanism of the half-toroidal CVT has been theoretically analyzed by applying two equations of motion. The first equation refers to sideslip force on the Hertzian contact area in the direction of the swing angle. The second equation refers to motion of the power roller and the hydraulic piston in the linear direction. However, neither analysis covers the effects of elastic deformation of the variator. Therefore, neither analysis can show correctly the behavior of the half-toroidal CVT during load transmission. In this paper, we will present a new analytical model for determining the elastic deformation and clearance of the half-toroidal CVT. We have implemented systematically our analytical model using MATLAB and Simulink. As a result, we can determine the behavior of the half-toroidal CVT during load transmission.

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To reduce a helicopter's rotor noise, a research on variable rotor speed transmission (VRST) was commenced. The variable speed mechanism comprises a high speed traction drive variator and a planetary differential. The traction drive input speed is 23,000 rpm to reduce weight and it is much higher speed than the automotive experience. With this system, the rotor speed can be variable from 80% to 100% continuously and 5 dB noise reduction can be achieved. To substantiate the high speed traction drive, an traction drive element test was conducted first and expected power transmitting capability under 23,000 rpm has been demonstrated. Then a full scale CVT with power split system was tested and power transmission capability up to 767hp was demonstrated. This proved the feasibility of the traction drive CVT for aircraft applications.

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A half-toroidal CVT for output speed control has two issues of swinging past the maximum attitude angle of the power-roller at a starting due to an infinitive speed-ratio command, and of instability in high rotational speed range of 23,000rpm. This paper describes control strategies for keeping the attitude angle of power roller to be constant at starting by measuring both speeds of input and output shafts instead of the attitude angle of the power-roller, and shows a way to stabilize the swinging motion of the power-roller through the safety-wire by a phase control of hydraulic circuits. And also shows the merit of hydraulic loading for a high speed rotational toroidal CVT.

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Reducing CO_2 emissions, which cause global warming, is one of the most important challenges facing the automobile industry today. As a result, the demand for high-powered continuously variable transmissions (CVT) has been steadily increasing. The traction-drive type half-toroidal CVT meets this demand. In 1999, the first mass-produced model of a traction-drive CVT for large-size passenger vehicles entered the Japanese automobile market. In this mass production model, there were two power rollers per cavity. In contrast, a toroidal mechanism with three rollers per cavity has been studied to attain greater compactness and higher torque capacity. A three-roller system has one and half times the torque capacity of a conventional two-roller system. In a full-toroidal CVT, the three-roller system has been analyzed for some time now. Interest in the full-toroidal system lies in the fact that the amount of power at one traction contact point is restricted by excessive spin loss. The half-toroidal CVT, however, does not have as much spin loss at traction contact point. Therefore, a half-toroidal with three rollers shows great potential as a high power-density transmission. There are some issues regarding the three-roller system that need to be considered, however. One issue is the development of a ratio control mechanism. Hydraulic pistons, which are attached to each trunnion, control transmission ratio in a three-roller system, these hydraulic pistons impede the design of a compact CVT, which is a major requirement for automobile application. In this paper, we will present a new concept for a three-roller system, which is compact in size and has high torque capacity.

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This paper will introduce the front drive unit of THS-C (Toyota Hybrid System-CVT), which is the second development stage of Toyota's hybrid system (hereafter THS), and the rear drive unit of E-Four, which is the world's first 4WD electric system. The THS-C and the E-Four went on sale in the Estima in June of 2001. The THS that was mounted in the Prius and went on sale in December 1997 was a "double motor type", that utilized both electric generator and drive motors. In contrast to this, the THS-C is a "single motor CVT type" that features the combination of a single motor with a belt type CVT, which allows it to switch between its electricity generation and drive functions depending on the driving conditions. The THS-C and the E-Four systems have been developed for use in minivan vehicles and 4WD of their respective weight classes, and are able to achieve remarkably good fuel efficiency.

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CYCLO ^<[○!R]> drive is power transmission device of K-H-V type which is combined with internal contact planetary gearing mechanism and constant speed internal gearing mechanism. With its excellent performance and reliability, although it has chalked up more than 7 million units so far, in order to respond the diversification and the higher performance of the market demands, SHI has developed the new #6000 series, especially focusing on the following three features. 1. Further miniaturization and weight-reduction to meet application requirements. 2. High efficiency with particular attention to the global environmental protection. 3. Noise reduction suitable for the surrounding nearby human-being. This report shows the developmental outline and the technological keys to achieve these purposes.

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Conventional gear cutting requires coolant, whose use complicates the work process and whose disposal endangers the environment. Dry gear cutting requires a tool that can be used without coolant and a gear cutting machine that discharges chips. We developed a hob and a gearshapercutter of high speed steels having proprietary TiAIN coatings and a dry gear hobbing machine and a dry gear shaping machine to realize hobbing and gearshaping. These dry cutting systems are environmentally friendly and cut total machining costs, double cutting speed, extend tool life 5times, and also the process capabilities are improved. As a result the product quality can be also improved.

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This report is briefing the purposes of lapping, the characteristic of Hypoid Gear lapping and YUTAKA L-45 CNC Lapping Machine.

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