| 摘要 |
An arrangement for the extraction of harmful gases from workplaces, the arrangement (1) exhibiting a carrier arm system (9) having at least two arms (19, 20, 21) connected telescopically with each other so that the carrier arm system (9) can be given different lengths, whereby the carrier arm system (9) is swivelable around a horizontal spindle (17) so that it can be swivelled in a vertical direction and placed in different positions between a downward-directed, preferably substantially vertical end position and an outward-directed preferably substantially horizontal end position. In order to permit the necessary balancing of both the swivelling and positioning of the carrier arm system (9) and the telescoping function of the arms of the carrier arm system (9) when the carrier arm system (9) is swivelled within a large sector, at least one first device (22) is arranged to generate balancing forces in order to facilitate swivelling of the carrier arm system (9) in the vertical direction between the end positions and/or to facilitate the retention of the carder arm system (9) in set positions between the end positions, and at least one second device (28) is arranged to generate balancing forces which allow the arms ( 19, 20, 21) of the carrier arm system (9) to remain in the positions relative to each other that they were given by the telescopic function, at least when the carrier arm system (9) is directed substantially downwards. |
