| 摘要 |
PCT No. PCT/CH79/00101 Sec. 371 Date Apr. 10, 1980 Sec. 102(e) Date Apr. 9, 1980 PCT Filed Jul. 16, 1979 PCT Pub. No. WO80/00299 PCT Pub. Date Mar. 6, 1980.The invention relates to electrical drive apparatus for a vertically displaceable blackboard. In order to obtain synchronous operation of such drive apparatus either one motor, one shaft, or two motors connected by means of an electrical shaft were employed. The apparatus according to the invention operates with an electric motor which is combined with a worm drive, a drive sheave, and a slip coupling to a unit which is mounted at the top inside the guide beams of the blackboard, with the motor arranged vertically and having a hollow shaft through which the drive cable is guided. One such drive apparatus is mounted in each guide beam at its top, with simultaneous switching on and switching off without an electrical shaft. |
