| 摘要 |
PCT No. PCT/EP97/04120 Sec. 371 Date Nov. 9, 1998 Sec. 102(e) Date Nov. 9, 1998 PCT Filed Jul. 29, 1997 PCT Pub. No. WO98/05556 PCT Pub. Date Feb. 12, 1998The catches (10) of the brackets (5) which can be made inactive by the elevator when the elevator is in the low position are designed to interact with corresponding cams (20, 21, 22) of different angular extents, keyed to a shaft (17) which is driven by a motor (22) whose speed and phase are electronically controlled and which is supported rotatably by the base of the machine. When a product is fed onto the elevator and its dimensions are measured by known means which then determine the travel of the film unwinding gripper in the packaging station, if necessary the cam shaft is made to rotate through a distance capable of causing the oscillation of the catches of the brackets which are to be disengaged, so that when the elevator rises the unnecessary brackets are already disengaged and oscillate slowly downwards. Immediately after the active travel of the elevator, the cam shaft rotates into the rest position, so that when the elevator is lowered again and causes the previously disengaged brackets to interact with the resetting stops (14) the catches of these brackets are reset so that they retain the brackets in the active position.
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