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A new three-pulley CVT (Continuously Variable Transmission) with a tensioner has been developed using dry hybrid V-belts. It can transmit higher torque than conventional two-pulley CVT without a tensioner, because the tensioner increases not only a lap angle where power is transmitting but also it can always keep the belt tension optimum. This study shows whether the Euler's power transmitting theory is applicable to the tensioner type CVT to characterize the CVT operation for preliminary design. The tensioner type CVT has also high shifting speed and it does not need large thrusts on both driving and driven pulleys during shifting since the minimum tension for torque transfer is assured in the slack-side string. The FEM analysis revealed the shifting mechanism and showed that the transmitting force distribution in the pulley groove for the newly developed CVT is almost the same as that for the conventional CVT.

In order to reveal the shifting mechanisms for CVT using a metal pushing V-belt, three shifting rates were introduced. The belt motion in the pulley groove was also characterized using mean coefficients of friction as parameters, which identify the slippage condition of the belt in the pulley groove. The experimental results showed that one of shifting rates, dR/ds was almost constant in the narrowing pulley regardless of both rotational speed and transmitted torque. Here, R is the belt pitch radius in the pulley and s is the length measured along the belt pitch line. This fact indicates that the shifting is primarily governed by elastic deformation of blocks of the belt. Power transmitting states were also evaluated using a different type of lubricating oil whose nominal coefficient of friction was higher than that for the conventional AT oil. The observed mean coefficients of friction vary due to oil although the basic response of the CVT unchanged.

The purpose of this study is to propose an effective model to estimate the excitation force accompanied with stick-slip between shoe and disc, considering the strain distribution on contact surface of the shoe, and then to propose an effective concept to design the brake which reduced the brake squeal under practical use. In order to investigate the influence of configuration of the hole, three types of discs were prepared in which the size of holes was different. The SPL (Sound Pressure Level) and the frequency of squeal for three types of discs were measured when the brake squeal was observed at conditions of low sliding speed. The change of stability of the brake shoe passing on hole was analyzed by 2-D simplified brake system model.

Brake discs have some holes in the flange for promoting heat dissipation as well as refreshing the pad surfaces. One-piece brake discs are desirable even for large sizes in order to reduce the production cost. However, cracks exceptionally occurred from some holes in the flange during braking under extremely severe test conditions for one-piece brake discs. On the other hand, no cracks were observed under the same condition for two-piece brake discs consisting of a hub and a flange. The objective of the present work is to show way cracks occur in the case of one-piece brake discs. Cyclic braking tests under extremely severe conditions were carried out using large one-piece brake discs having some hole in their flange. When the number of braking cycles was beyond 300, some tiny cracks occurring around holes were found. They grew in the radial direction of the brake discs.

The purpose of this study is to clarify how the residual stress determined by the configuration of weight reduction holes affects the crack initiation in the brake discs for large motorcycles under the over loading condition. Two kinds of test samples of the one-piece type brake disc were used where the configuration of the weight reduction holes were different. The test result showed that the crack initiation life was significantly changed due to the configuration of weight reduction holes. The 3D FEM results of heat transfer and thermal stress analysis explained that the stress relaxation was dependent on the configuration of weight reduction holes of the disc because the initial thermal stress was directly determined by the simple stress distribution around each hole. This study confirmed that the configuration of weight reduction holes plays a decisive role in determining the design of the brake disc.

An implicit finite element (FE) model was developed to accurately analyze the power transmitting mechanisms of CVT using a dry hybrid V-belt. The numerically analyzed results well agreed with the experimental results. The effects of angle mismatching of pulley groove and flange deflection on the power transmission were examined by using the present approach. The calculated results showed that the blocks were subjected to an over-load due to the pulley flange tilting. The angle mismatching between the pulley groove angle and the block wedge angle strongly affected the power transmission at both steady and transitional states. It was also found that the block tilting in the pulley groove affected the power transmission.

In Metal V-belt type CVT, an elastic deformation of blocks determines the shifting speed and the pulley thrusts at transitional state. Both driving and driven pulley thrusts were calculated by considering the forces acting on blocks at a pulley entrance, which agreed with the experimental results at not only steady state but also transitional state. The frictional performance of CVT fluids and the frictional characteristics between blocks and a pulley were evaluated by applying the mean coefficient of friction as a friction parameter. It was found from the experiments that the estimated coefficient of friction of CVT fluids was not constant with respect to operating conditions. It changed due to relative sliding speed between blocks and the pulley, sliding direction and normal pressure acting on V-surface of the block.