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By utilizing the self-locking property of belt, a novel one-way clutch was developed. This device uses a steel belt. It can transmit torque even under off-centered conditions. Some experiments were carried out under several off-centered conditions. The relation between the angular velocities ratio [Formula: see text] and the magnitude of off-centered distance δ was investigated. Here, the subscripts i and P denote the inner shaft and the power ring, respectively. The angular velocities obtained from the experiments were compared with the theoretical values. The experimental results almost corresponded to the theoretical calculations. When there is a parallel misalignment between input and output shafts, the belt is automatically coiled or uncoiled around the shaft with rotation. Some endurance tests on the clutch were also carried out by changing the magnitude of off-centered distance δ under a constant brake torque. The fatigue life of the belt was shortened by an increment of the off-centered distance.

Theoretical study was carried out to investigate the frictional property of belt wrapped three times around a circular shaft. A belt equation of fractional expression was derived. The self-locking mechanism was investigated theoretically by the equation. The discriminant of self-locking condition was clarified. The necessary conditions for self-locking are µ b < µ and sufficient wrapping angle of the belt, where µ is the coefficient of friction between the belt and shaft and µ b is the coefficient of friction between the belt and belt. According to the formula derived, self-locking occurs even under a realistic condition. It occurs when the ratio of belt tensions becomes 0 or negative. Providing the coefficient of friction µ and the ratio of the coefficients of friction κ = µ b /µ, some critical over-wrapping angles for self-locking were calculated numerically. Furthermore some normal force distributions in self-locking conditions were calculated theoretically.

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