Flex shaft—tool connection for power operated rotary knife

1. A flexible shaft drive transmission coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission comprising:

a) an outer casing assembly having a drive motor end and a tool end and including a driver assembly coupling including a central cylindrical body and a reduced diameter distal section and an inner surface defining a throughbore extending through a proximal end wall and a distal end wall of the driver assembly coupling, the inner surface including a stepped shoulder spaced from the proximal and distal end walls, a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling, the bushing defining a longitudinal central opening; and

b) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing.

2. The flexible shaft drive transmission of claim 1 wherein the body of the coupler fitting is cylindrical and the longitudinal central opening of the bushing is longitudinal.

3. The flexible shaft drive transmission of claim 2 wherein the longitudinal central opening of the bushing is concentric with a central longitudinal axis of the flexible shaft drive transmission.

4. The flexible shaft drive transmission of claim 1 wherein the enlarged head of the coupler fitting defines a drive fitting aligned with a central axis of rotation of the drive transmitting shaft assembly.

5. The flexible shaft drive transmission of claim 4 wherein the drive fitting comprises a square drive fitting.

6. The flexible shaft drive transmission of claim 1 wherein a shaft fitting is affixed to the tool end of the drive transmitting shaft and the coupler fitting is secured to the shaft fitting to couple the coupler fitting to the tool end of the drive transmitting shaft.

7. The flexible shaft drive transmission of claim 6 wherein the coupler fitting is secured to the shaft fitting via a threaded interconnection.

8. The flexible shaft drive transmission of claim 1 wherein the outer casing assembly includes an outer casing extending between a first coupling at the drive motor end of the outer casing assembly and a second coupling at the tool end of the outer casing assembly.

9. The flexible shaft drive transmission of claim 8 wherein the bushing is disposed in the second coupling.

10. The flexible shaft drive transmission of claim 1 further including a driver assembly coupled to the tool end of the outer casing assembly and comprising a driver shaft coupled to the enlarged head of the coupler fitting of the drive transmitting shaft assembly.

11. A flexible shaft drive transmission assembly coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission assembly comprising:

a) a flexible drive shaft transmission including: 1) an outer casing assembly having a drive motor end and a tool end and including a driver assembly coupling including a central cylindrical body and a reduced diameter distal section and an inner surface defining a throughbore extending through a proximal end wall and a distal end wall of the driver assembly coupling, the inner surface including a stepped shoulder spaced from the proximal and distal end walls, a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling a bushing including an enlarged distal head and a cylindrical body extending from the enlarged distal head received in the throughbore of the driver assembly coupling, the enlarged distal head of the bushing seated against the stepped shoulder of the inner surface of the driver assembly coupling, the bushing defining a longitudinal central opening; and 2) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing; and

b) a driver assembly including a tube assembly releasably coupled to the tool end of the outer casing assembly and an elongated driver shaft assembly at least partially disposed within the tube assembly and operatively coupled to coupler fitting of the drive transmitting shaft assembly.

12. A flexible shaft drive transmission coupled between a drive motor and a gear train of a power operated tool, the flexible shaft drive transmission comprising:

a) an outer casing assembly having a drive motor end and a tool end and including an outer casing and a driver assembly coupling affixed to a tool end of the outer casing assembly, the driver assembly coupling including a distal end wall and a proximal end wall and a thoughbore extending longitudinally therebetween, the driver assembly coupling including a central cylindrical body and a reduced diameter distal section extending from the central cylindrical body and having a threaded portion on an outer surface of the reduced diameter distal portion adjacent the distal end wall of the driver assembly coupling and a bushing positioned within the throughbore of the driver assembly coupling at the tool end of the outer casing assembly, the bushing defining a longitudinal central opening; and

b) an elongated drive transmitting shaft assembly rotatable within the outer casing assembly, the elongated drive transmitting shaft assembly including a flexible drive transmitting shaft having a motor end and a tool end, the drive transmitting shaft assembly further including a coupler fitting coupled to the tool end of the drive transmitting shaft, the coupler fitting including a body and an enlarged head extending distally from the body, the body fitting within the longitudinal central opening of the bushing and the enlarged head having a diameter greater than a diameter of the longitudinal central opening of the bushing to constrain axial movement of the drive transmitting shaft with respect to the outer casing.

13. The flexible shaft drive transmission of claim 12 wherein the body of the coupler fitting is cylindrical and the longitudinal central opening of the bushing is longitudinal.

14. The flexible shaft drive transmission of claim 13 wherein the longitudinal central opening of the bushing is concentric with a central longitudinal axis of the flexible shaft drive transmission.

15. The flexible shaft drive transmission of claim 12 wherein the enlarged head of the coupler fitting defines a drive fitting aligned with a central axis of rotation of the drive transmitting shaft assembly.

16. The flexible shaft drive transmission of claim 15 wherein the drive fitting comprises a square drive fitting.

17. The flexible shaft drive transmission of claim 12 wherein a shaft fitting is affixed to the tool end of the drive transmitting shaft and the coupler fitting is secured to the shaft fitting to couple the coupler fitting to the tool end of the drive transmitting shaft.

18. The flexible shaft drive transmission of claim 17 wherein the coupler fitting is secured to the shaft fitting via a threaded interconnection.

19. The flexible shaft drive transmission of claim 12 wherein the outer casing assembly includes the outer casing extending between a first coupling at the drive motor end of the outer casing assembly and the driver assembly coupling at the tool end of the outer casing assembly.

20. The flexible shaft drive transmission of claim 12 wherein an inner surface of the driver assembly coupling defines the throughbore and includes a stepped shoulder spaced from the proximal and distal end walls, the enlarged distal head of the bushing being seated against the stepped shoulder.

21. The flexible shaft drive transmission of claim 12 further including a driver assembly coupled to the tool end of the outer casing assembly and comprising a driver shaft coupled to the enlarged head of the coupler fitting of the drive transmitting shaft assembly.