| 摘要 |
In a printing office machine a movable print head is driven by a device comprising a fixedly mounted lead screw (10) and a co-operating nut device (16) driven by an electric motor (34, 35). The nut device is rotatably mounted in a carrier frame (31) and comprises an inner tube (17) which is journalled on the lead screw (10). An outer tube (25) is journalled on the inner tube (17). An end part of the outer tube (25) bears against a flange (26) on the inner tube (17) under friction. The two tubes are turnably interconnected by spring means (30). The free ends of the tubes (17, 25) support ball bearings (20, 28) or the like which bear on flanks (14, 15) of grooves (13) cut in the lead screw (10). Each bearing co-operates with the groove flank which faces the respective tube end. The drive device has a very great freedom from play at the same time as the friction prevailing between the nut device and the lead screw is minimized. |
