| 摘要 |
A tensioning apparatus for metal strip, e.g. for advancing the metal strip through a processing station, for stretching the metal strip, or the like, comprises at least two sets of rolls (bridles) each comprising a pair of rolls in spaced apart relationship with the strip extending between the sets and over and under shooting respective rolls thereof. The drive system comprises a drive motor connected to one of the rolls of one of the sets (bridles) through a superimposing transmission (e.g. a three-element differential), one element of which is connected to the motor, another element of which is connected to the roll and a third element of which is connected by a shaft to a corresponding roll of the other pair via a similar three-element superimposition transmission. Another element of the latter transmission is connected to the roll of this other pair while a hydraulic motor is connected to the third element. Other rolls of the two sets are driven via hydraulic motors and/or similar transmissions, the hydraulic motors being connected to a common pressure line with controlled pressure so that the torques supplied to the rolls successively engaging the band are stepped.
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