| 摘要 |
PROBLEM TO BE SOLVED: To provide a no-back device to provide high durability without application of a brake through friction by a friction disc and the generation of heat. SOLUTION: A no-back device is provided with a back rotation block mechanism to block reverse rotation by an operation force from the load side. The back rotation block mechanism comprises a tooth-shaped block disc 33 fixed at a ball screw lever 31 and having a tooth shape 33T formed at an outer periphery; a lock claw 34 moved forward to and backward from the tooth shape 33T of the tooth-shaped block disc 33, and blocking rotation of the ball screw lever 31 or bringing the rotation into a free state; a moving member 28 reciprocating only in an axial direction toward a rotation drive shaft 29 and moving the lock claw 34 forward to and backward from the tooth shape T; and cam mechanisms 25 and 25K axially displacing the moving member 28 when the rotation drive shaft 24 is rotationally driven both in directions to the right and the left. Thus, when a reverse rotation drive force occurs to the ball screw lever 31 by an operation force from the load side, the lock claw 34T is advanced to the tooth shape 33T of the tooth shape block disc 33 and blocks rotation thereof, and a no-back function is achieved.
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