| 摘要 |
Rotational overtravel stops are often crucial components of actuators used in environments where not only cost but also power requirements, reliability, weight, size and simplicity are important. A bi-directional overtravel stop for a rotatable actuator shaft is disclosed which includes first and second brake plates secured for rotation with the shaft in opposite directions by a pair of oppositely disposed one-way clutches. A non-rotatable brake member is mounted for axial movement relative to the shaft and means are provided for biasing the brake member to frictionally engage one or the other of the brake plates when the shaft has reached the selected limit of its rotation in one direction or the other. The actuating structure of the overtravel stop includes a sleeve over the shaft and secured to the brake member, and a tubular threaded member over the sleeve, said threaded member and sleeve being secured against relative rotation and allowing telescoping relative to one another. Stops are provided so that, at either end of the telescoping motion, the sleeve is appropriately biased to move the brake member toward engagement with the appropriate brake plate. The threaded member is driven axially by a nut which is itself driven by the shaft. The one-way clutches are springs wound spirally around the shaft with one end of each spring being fixed to its associated brake plate.
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