| 摘要 |
A power transmission device having a disengagement mechanism (7), whereby the device when not driven by a motor (5) may be operated manually. With motor drive, power is transmitted via a worm wheel (3) to a pawl (11 or 12) in a pawl mechanism, and therefrom further on to a boss (9) on which the pawls are pivotably mounted, said boss (9) being mechanically coupled to an apparatus (10) which is to be driven. The pawls (11, 12) are spring tensioned by means of a common arcuate spring (14). On manual operation, a shaft (15) mounted coaxially with the boss and rotatable relative thereto is turned in one or the other direction. The shaft (15) is provided with an arm (16) which, on contact with one of the pawls (11, 12), brings the pawl out of engagement with the worm wheel and causes rotation of the boss (9) and thereby of the apparatus (10), while the other pawl (12 or 11) on the influence of the spring (14) is caused to slip along an inner circumferential area (3'') of the worm wheel (3).
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