| 摘要 |
<p>To achieve a synchronisation, such devices operated either with a motor and a mechanical shaft, or with two motors connected by a so-called electrical shaft. The device is operated by an electrical motor (10) forming with a helical wheeled and worm transmission (20), a driven poulie (40) and an elastic coupling, a unit which may be located on top of the guiding upright of the blackboard into which the motor is arranged vertically and has a hollow shaft (31) through which passes the driving cable. Such a device is mounted in the inside and on top of each of the two guiding uprights. These two devices are set on and off at the same time and do not require electrical shaft. </p> |
