Telescoping dual-spindle drive

1. A linear drive having first and second ends, the linear drive comprising:

a first element having a third end connectable to a first adjustable part, the third end defining the first end of the linear drive, the first element defining first spindle threads on a surface thereof;

a second element having a fourth end connectable to a second adjustable part, the fourth end defining the second end of the linear drive, the second element defining second spindle threads on a surface thereof;

a drivable connecting element comprising:

a double nut having first and second nut threads engaging the first and second spindle threads on the first and second elements, respectively,

such that the first and second elements are connected to the drivable connecting element by respective pairs of corresponding first and second spindle threads and first and second nut threads; and

an actuating device to drive the drivable connecting element, the actuating device comprising an actuator at the third end of the first element, and a hollow tubular connecting part drivably coupled to the actuator and non-rotationally coupled to the drivable connecting element, the connecting part at least partially surrounding the first element;

wherein the connecting part is engaged with the drivable connecting element to transfer a drive force from the actuator to the drivable connecting element, to cause rotation of the drivable connecting element, and

wherein the pairs are oppositely threaded pairs, and the drivable connecting element is drivable by the actuator to rotate relative to the first and second elements to telescopically extend or withdraw the linear drive and adjust the distance between the first and second adjustable parts.

2. The linear drive of claim 1 , wherein the actuator defines a through-opening receiving the third end of the first element.

3. An adjustable unit comprising:

the linear drive of claim 1 connected to at least one of the first and second adjustable parts,

wherein the first and second adjustable parts are adjustable relative to each other, and

the linear drive is configured to adjust at least one of the adjustable unit and the first and second adjustable parts.

4. The linear drive of claim 1 , wherein the first and second elements are coaxial to each other.

5. The linear drive of claim 1 , wherein at least one of the first and second elements comprises a hollow element with an interior space, into which the other of the first and second elements is at least partially retractable.

6. The linear drive of claim 1 , wherein the first and second elements comprise threaded spindles, each of the first and second spindle threads of the pairs of threads comprises substantially a same pitch, and the pair of threads on the first and second threaded spindles turn in opposite directions.

7. The linear drive of claim 1 , wherein at least one of the first and second elements comprises a stop for limiting a linear movement of the linear drive.

8. The linear drive of claim 1 , further comprising at least one guide device for guiding at least one of the first and second elements.

9. The linear drive of claim 8 , wherein the at least one guide device is integrated into at least one of the first and second elements.

10. The linear drive of claim 8 , wherein the at least one guide device comprises a separate component in the drivable connecting element.

11. The linear drive of claim 1 , wherein the drivable connecting element comprises two axially separated connecting areas including said first and second nut threads, respectively, and wherein the threads on the drivable connecting element are axially aligned and correspond to the threads of the first and second elements.

12. The linear drive of claim 11 , wherein a distance between the connecting areas corresponds to a length of at least one of the threads of the first and second elements, so that the at least one of the threads of the first and second elements is retractable into an interior space defined between the connecting areas and a connecting wall of the drivable connecting element.

13. The linear drive of claim 12 , wherein the distance between the connecting areas corresponds substantially to an axial length of the interior space of the drivable connecting element.

14. The linear drive of claim 12 , wherein the drivable connecting element comprises at least one driver device mounted on a side of the connecting wall of the drivable connecting element facing away from the interior space of the drivable connecting element.

15. The linear drive of claim 1 , wherein the connecting part and the drivable connecting element each have corresponding engaging means for transmitting a drive force from the actuator to the drivable connecting element, the engaging means preventing rotation between the connecting part and the drivable connecting element.

16. The linear drive of claim 1 , wherein the hollow interior space of the connecting part comprises a length corresponding substantially to a length of one of the first and second spindle threads formed on the one of the first and second elements to be accommodated.

17. The linear drive of claim 3 , wherein the first and second elements are nonrotatable with respect to the first and second adjustable parts, respectively.

18. The adjustable unit of claim 3 , wherein at least one of the first and second adjustable parts comprises a hollow adjustment subspace, in which the linear drive is at least partially accommodated.

19. The adjustable unit of claim 3 , wherein at least one of the first and second adjustable parts is adjustably connected to the linear drive by a driver of the linear drive.

20. The adjustable unit of claim 3 , wherein the adjustable unit is a piece of furniture, selected from the group consisting of: a table leg, a chair leg, a stool leg, a desk leg, a bookcase leg, a cabinet leg, a bed leg, a bed adjusting device, and a computer desk.