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The objective of this study was to investigate the change of relative local velocity in each pulley groove at sliding between the belt and pulleys for a metal-pushing V-belt type CVT where micro elastic slips were inevitably accompanied to transmit power, while the transmissions were widely adopted to provide comfortable driving by continuously automatically adjusting the speed ratio. Local changes of wrapping radial position and velocity of the belt in each pulley groove of the CVT were simultaneously measured by a potentiometer with a spinning roller in the experiments. The mechanical power generated by the AC motor was transmitted through the CVT unit from the driving axis to the driven axis as usual under practical conditions while the speed ratio was set to 1.0. Pulley clamping force was applied by oil pressure.

The objective of this study was to investigate the local change of PV value on the end faces of rocker pins driven by a high-performance chain under transmitting torque conditions. A test bench system was prepared to evaluate the behavior of the chain belt under driven state. Local contact force of the pin was measured by strain gauges attached to a specific modified pin for which the thickness was partly reduced by machine work. Change of PV value on the end face of the pin was also calculated by considering the change of pressure generated by contact force and sliding velocity of rocker pin. Autorotation angles of the rocker pins in the groove of driving and driven sheaves were investigated by replacing the normal pulleys with visibly transparent sheaves made with acrylic resin. The representative loading points were also calculated assuming that the pin was regarded as a simple beam where an eccentric compressive load was applied.

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.

The mechanism of permanent deformation of pressure plates has been investigated under very severe conditions, which are used for automobile clutches. Sliding tests were performed, where an extreme overload was applied to the pressure plate. It is found from the test results that the residual stress in the circumferential direction varied from compression to tension after the sliding test near the sliding surface of the plate. FE (Finite element) calculations were also conducted taking both plastic deformation of the plate due to thermal expansion and geometrical non-linearity into account. The FE calculations agreed well with the experimental results. The permanent deformation mechanism for pressure plates was summarized as follows. Compressive yielding of the plate occurs at the heating stage near the sliding surface. The residual stress in tension appears in the sliding surface when the plate becomes cool, and it deflects the plate like a bowl.

In order to reveal the mechanism of noise generation from CVT (Continuously Variable Transmissions) using a dry hybrid V-belt, the power spectrum of sound from a two-pulley CVT system and its variation with respect to rotational speed were measured. The experimental results showed that the frequency of the first peak in the power spectrum of the observed sound linearly increased with increasing the rotational speed of the pulley. The sound frequency of the first peak coincides with the frequency derived from the belt block pitch and the belt speed. Then, sound intensity analyses were conducted to identify noise sources of CVT. The experimental results reveal that unpleasant sound whose frequency is high occurs due to the collision or slip between CVT blocks and the pulley groove at the entrance and the exit of V-groove pulleys. Pulley surface roughness strongly affects the noise level. Additionally, the location of noise source varies due to surface roughness of the pulley groove.

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.

Two-layered clutch plates manufactured by a new process using BMC show a significant deflection. Two methods solving such deflection were alternatively developed in this study. Changing the composition of the clutch plate appeared to be useless while after-curing on deflected clutch plates was effective. Thermal cycles or high pressure for after-cure did not reduce the deflection. However, applying after-cure with a sloped mold reduce the deflection without increasing the disk density.

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.

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 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.