What is a sprag type one-way clutch?

A sprag-type one-way clutch consists of an outer ring, figure-eight wedges, retaining springs, and an inner ring, and these wedges work in a similar manner to the rollers in a roller-type one-way clutch.

A sprag-type one-way clutch consists of an outer ring, figure-eight wedges, retaining springs, and an inner ring, and these wedges work in a similar manner to the rollers in a roller-type one-way clutch. When the outer ring in the figure rotates counterclockwise relative to the inner ring, the wedge is pushed and inclined, leaving a certain space between the inner and outer rings, so that the clutch will not be locked. In other words, the sprag type one-way clutch shown allows the outer race to rotate counterclockwise relative to the inner race, or the inner race clockwise relative to the outer race, at all times.

However, if the outer ring tries to turn clockwise relative to the inner ring, the wedges, due to their geometry, will get stuck between the inner and outer rings, locking them together. That is to say, once the wedge blocks the inner and outer rings, the one-way clutch locks up, preventing the outer ring from rotating clockwise relative to the inner ring, or the inner ring rotating counterclockwise relative to the outer ring. In order to ensure that the wedge can be reliably wedged between the inner and outer rings, a retaining spring is installed in this one-way clutch, so that the wedge can always keep a little inclination according to the direction that can lock the two turns. The failure mode and manufacturing materials of the wedge type one-way clutch are the same as those of the roller type one-way clutch.

The wedge type one-way clutch includes an outer race and an inner race arranged in the outer race, the outer race and the inner race are radially spaced from each other and arranged coaxially for relative rotation, and a plurality of them are arranged on the outer race and the inner race a wedge between the rings for transmitting torque, an annular retainer for retaining the wedge, and a spring member for supporting the wedge between it and the retainer and for biasing the wedge in a meshing direction, characterized in that, The cage is provided with a cylindrical portion having a radially extending window portion in which the wedge is mounted for pivotal movement, and the spring member is guided substantially circularly by the outer circumferential surface of the cylindrical portion.