CONTROLLED COUPLING HYDRA-MATIC
Sprag clutches. A sprag clutch is an over -running clutch which allows rotation
in one direction only. It consists of an inner race,
an outer race, and the sprag assembly.
|One diagonal dimension of each sprag is greater than the distance between the inner and outer race, while the other diagonal is less. This causes the sprags to wedge and prevent rotation in one direction, and to allow free rotation in the opposite direction.|
|The sprag assembly itself consists of sprags, retainer rings, and a flat spring. The sprags are mounted at close intervals between the two concentric retaining rings. The flat spring is located between the rings and surrounds the narrow "wrists" of the sprags.||When the outer race is held, and the inner race is turned clockwise, the sprags pivot so that their short diagonals are between the races. This frees the sprags from the races and allows free rotation.|
|When the inner race is turned counter-clock- wise, the sprags pivot so that their long diagonals are between the races. This causes the sprags to wedge tightly between the race and positively stops rotation.|
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