| 摘要 |
An auxiliary driving device being attached to a primary driving device of a rolling door and including a gear engaged with a gear wheel of the primary driving device, a motor having an axle, a lower disc with a pinion slidably engaged on the axle, a spring biasing the pinion and the lower disc upward, an upper disc disposed above the lower disc, three balls engaged in the recesses formed in the discs, the pinion moves downward to engage with the gear when the first motor is energized so that the spindle can be driven to rotate by the motor.
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