| 摘要 |
An inner leg telescopically fits within an outer leg and includes a motor coaxially mounted to an end remote from the outer leg. A drive screw is coupled to the motor shaft and extends through a drive nut in an axially extending drive nut riser. As the motor rotates the drive screw, the inner leg extends and retracts from the outer leg. In a preferred embodiment of the invention, the drive nut riser is a hollow cylindrical tube extending substantially the length of the outer tube to position the drive nut near the intersection between the inner and outer legs when fully extended. Such an arrangement allows a motor to be coaxially mounted within the inner leg and, therefore, concealed and provides the desired extension and retraction of the legs for adjustment to different operative positions.
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