| 摘要 |
An adjustment device 1 comprises a handle portion 2 that is grasped by a user, a spindle portion 4 adapted to engage an element to be rotated against a resistive torque, first permanent magnets 14 attached to the handle portion 2 and second permanent magnets 15 attached to the spindle portion 4. There is magnetic attraction between the first and second magnets 14, 15 to form a magnetic coupling. The handle portion 2, spindle portion 4 and magnetic coupling are arranged so that when a relative torque below a predetermined torque is applied to the device 1, the handle portion 2 and spindle portion 4 will rotate together, due to the magnetic coupling. When a relative torque greater than the predetermined torque is applied to the device 1, the magnetic coupling will be overcome and the handle portion 2 will rotate with respect to the spindle portion 4. The device preferably includes an adjustment arrangement for setting the predetermined torque, by varying the relative distance between the first and second magnets 14, 15. The device is suitable for tightening drum nuts when tuning a percussive drum skin.
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