| 摘要 |
An extendable tool having an internal drive assembly is disclosed. The extendable components of the internal drive assembly are two, or more, telescoping drive shafts each having an alignment structure. The alignment structure ensures that the drive shafts generally maintain their circumferential alignment relative to each other, i.e. the shafts rotate together and maintain their orientation, while allowing the drive shafts to slide axially relative to each other. In one embodiment the drive shafts have a non-circular cross-section, and more preferably, a square cross-section. Each inner drive shaft has a cross-sectional area that is slightly smaller than the next larger outer drive shaft. Thus, the drive shafts may slide axially relative to each other. However, when the drive shafts are rotated, the non-circular shape causes the inner drive shaft and the larger outer drive shaft to engage each other and rotate together.
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