Gearless torque drive

1. A torque-limiting mechanism comprising:

an upper shank component comprising a proximal end, a distal end, an axial bore connecting the proximal end and the distal end, and a first undulated torque-limiting interface disposed on the proximal end;

a lower shank component comprising a proximal end, a distal end, a drive socket disposed between the proximal end and the distal end, and a second undulated torque-limiting interface disposed on the proximal end, wherein the upper shank component and the lower shank component are aligned along an axis in the direction of the axial bore and the drive socket with the first torque-limiting interface in contact with the second torque-limiting interface; and

a compressible biasing element with a 50 to 100 durometer rating configured to apply compressive force (F) along the axis to compress the first torque-limiting interface against the second torque-limiting interface;

wherein the upper shank component and the lower shank component are configured to engage to rotate together when torque is applied to the lower shank component via the drive socket; and,

wherein the upper shank component and the lower shank component are configured to disengage when a predetermined torque limit is exceeded,

the first torque-limiting interface comprises a first plurality of non-metallic undulations arranged around the axial bore and separated by a first plurality of transition regions;

the second torque-limiting interface comprises a second plurality of non-metallic undulations arranged around the drive socket and separated by a second plurality of transition regions; and

each undulation comprises an upslope, a peak, and a downslope, wherein each downslope has a declination angle of between 5 and 30 degrees such that degradation is mitigated between the first and second pluralities of undulations.

2. The torque-limiting mechanism of claim 1 , wherein: the first and second pluralities are equal in number.

3. The torque-limiting mechanism of claim 1 , wherein: each upslope has an inclination angle between 3 degrees and 15 degrees.

4. The torque-limiting mechanism of claim 1 , wherein: each upslope has an inclination angle between 5 degrees and 9 degrees.

5. The torque-limiting mechanism of claim 1 , wherein: each upslope has an inclination angle between 6 degrees and 8 degrees.

6. The torque-limiting mechanism of claim 1 , wherein: each upslope has an inclination angle of 7 degrees.

7. The torque-limiting mechanism of claim 1 , wherein the predetermined torque limit is between 0.1 Newton-meter and 3.0 Newton-meter.

8. The torque-limiting mechanism of claim 1 , wherein the predetermined torque limit is between 3.0 Newton-meter and 6.0 Newton-meter.

9. The torque-limiting mechanism of claim 2 wherein the first torque-limiting interface and second torque-limiting interface each comprise three undulations.

10. The torque-limiting mechanism of claim 2 wherein the first torque-limiting interface and second torque-limiting interface each comprise four undulations.

11. The torque-limiting mechanism of claim 2 wherein the first torque-limiting interface and second torque-limiting interface each comprise five undulations.

12. The torque-limiting mechanism of claim 1 wherein the torque-limiting mechanism provides a predetermined torque between 0.1 Newton-meter and 6 Newton-meters of torque at a rotational speed between 50 RPM and 1300 RPM over at least one of 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 105, 110, 120, 150, 180, 200, 220, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2100, 2200, 2300, 2400, or 2500 actuations while remaining within a specified operational range.

13. The torque-limiting mechanism of claim 1 , wherein each downslope has a declination angle of between 10 and 30 degrees.

14. The torque-limiting mechanism of claim 13 , wherein each downslope has a declination angle of between 10 and 20 degrees.

15. The torque-limiting mechanism of claim 14 , wherein each downslope has a declination angle of 15 degrees.

16. The torque-limiting mechanism of claim 1 , wherein each upslope has a functional path length defined along a midpoint of each undulation, each downslope has a functional path length defined along the midpoint of each undulation, and the ratio of the functional path length of the upslope to the functional path length of the downslope is between 2.2:1 and 1.8:1.

17. The torque-limiting mechanism of claim 1 , wherein the lower shank component includes a retaining cavity configured to receive the compressible biasing elements, such that the compressible biasing element is retained within the retaining cavity when the compressible biasing element is compressed to expand radially.

18. The torque-limiting mechanism of claim 2 , wherein each peak has a length between an adjacent upslope ad an adjacent downslope, each transition region has a length between an adjacent upslope and an adjacent downslope, and the length of the peak is equal to the length of the transition region.

19. The torque-limiting mechanism of claim 1 , wherein the ratio of the first plurality of undulations arranged around the axial bore to the first plurality of transition regions is at least 65:35, and

wherein the ratio of second plurality of undulations arranged around the drive socket to the second plurality of transition regions is at least 65:35.

20. The torque-limiting mechanism of claim 1 , further comprising an actuation indicating system configured to create an audible indication when the upper shank component and the lower shank component have slipped past each other.