| 摘要 |
1,244,581. Bridge crane crab drives. K. MULLER, [trading as W. & M. AUTOMATION KARL MULLER]. 26 Jan., 1970 [21 Nov., 1969], No. 3710/70. Heading B8B. A bridge crane crab 11 runs on wheels 12, 12a on a track comprising two horizontal rails 13, 13a arranged one above the other. A chain drive for the crab 11 comprises a chain 3 having runs parallel to the track and characterized by means for deflecting the chain 3 through 90 degrees at desired stopping positions. As shown a driver 9 attached to the chain 3 engages a guide 10 on the crab 11. The chain 3 passes around sprocket 2 driven by a geared brake motor 1, between sprockets 4, 5, around sprocket 6 and over tensioning sprocket 7. The velocity of the crab 11 is zero when the driver 9 is at any of the stopping positions 18, 19, 20 and if the motor 1 is switched off immediately prior to any one of these positions relatively little mass has to be brought to rest by the brake. In addition the starting load on the motor 1 is reduced due to the initial small acceleration. |
