Controllable coupling assembly having forward and reverse backlash

1. A controllable coupling assembly having forward and reverse backlash, the assembly comprising:

a plurality of forward locking elements, each of the forward locking elements having a load-bearing surface;

at least one reverse locking element; and

first and second coupling members supported for relative rotation about a common rotational axis, the coupling members including:

a first coupling face having a set of forward pockets angularly spaced about the axis, each of the forward pockets receiving one of the forward locking elements and defining a forward load-bearing surface adapted for abutting engagement with the load-bearing surface of its respective forward locking element;

a second coupling face having a set of reverse locking formations adapted for abutting engagement with the at least one reverse locking element to prevent the relative rotation in a reverse direction about the axis; and

a third coupling face that opposes the first coupling face, the third coupling face having a set of forward locking formations, each of the set of forward locking formations being adapted for abutting engagement with one of the forward locking elements to prevent the relative rotation in a forward direction about the axis, wherein the number of forward locking elements is different than the number of reverse locking elements, wherein the number of forward locking formations is different than the number of reverse locking formations and wherein either the forward backlash is a non-zero integer multiple of the reverse backlash or the reverse backlash is a non-zero integer multiple of the forward backlash to prevent the coupling assembly from inadvertently binding in both directions about the axis.

2. The assembly as claimed in claim 1 , further comprising a fourth coupling face that opposes the second coupling face, the fourth coupling face having at least one reverse pocket, each reverse pocket receiving a reverse locking element and defining a reverse load-bearing surface adapted for abutting engagement with a load-bearing surface of its respective reverse locking element.

3. The assembly as claimed in claim 1 , wherein the forward pockets are grouped into at least one set and wherein the forward pockets in each set are uniformly angularly spaced.

4. The assembly as claimed in claim 3 , wherein the forward pockets are grouped into two or more sets.

5. The assembly as claimed in claim 1 , wherein the first coupling member has the first and second coupling faces and the second coupling member has the third coupling face.

6. The assembly as claimed in claim 1 , wherein the first coupling face is oriented to face axially in a first direction along the axis, and wherein the second coupling face is oriented to face axially in a second direction opposite the first direction along the axis.

7. The assembly as claimed in claim 1 , wherein the forward and reverse locking elements are locking struts.

8. The assembly as claimed in claim 1 , wherein the forward and reverse locking formations are notches.

9. The assembly as claimed in claim 1 , wherein the first coupling member is a splined ring.

10. The assembly as claimed in claim 1 , wherein the first and third coupling faces are annular coupling faces that oppose each other.

11. The assembly as claimed in claim 1 , further comprising a plurality of reverse locking elements and a third coupling member having a fourth coupling face that opposes the second coupling face, the fourth coupling face having a set of reverse pockets angularly spaced about the axis, each of the reverse pockets receiving one of the reverse locking elements and defining a reverse load-bearing surface adapted for abutting engagement with a load-bearing surface of its respective reverse locking element.

12. The assembly as claimed in claim 11 , wherein the reverse pockets are grouped into at least one set and wherein the reverse pockets in each set are uniformly angularly spaced.

13. The assembly as claimed in claim 12 , wherein the reverse pockets are grouped into two or more sets.

14. The assembly as claimed in claim 11 , further comprising:

a control member mounted for controlled, shifting movement between the second and fourth coupling faces relative to the set of reverse pockets and operable for controlling position of the reverse locking elements, the control member allowing at least one of the reverse locking elements to engage at least one of the reverse locking formations in a first position of the control member and wherein the control member maintains the reverse locking elements in their pockets in a second position of the control member.

15. The assembly as claimed in claim 14 , wherein the control member comprises a slide plate controllably rotatable about the rotational axis between the first and second positions.

16. The assembly as claimed in claim 14 , further comprising a control element coupled to the control member to controllably shift the control member.

17. The assembly as claimed in claim 11 , wherein the assembly further comprises:

a generally round snap ring that is received by an annular groove in the third coupling member to retain the members together and prevent axial movement of the members relative to one another.

18. A controllable clutch assembly having forward and reverse backlash, the assembly comprising:

a plurality of forward locking elements, each of the forward locking elements having a load-bearing surface;

at least one reverse locking element; and

first and second clutch members supported for relative rotation about a common rotational axis, the clutch members including:

a first coupling face having a set of forward pockets angularly spaced about the axis, each of the forward pockets receiving one of the forward locking elements and defining a forward load-bearing surface adapted for abutting engagement with the load-bearing surface of its respective forward locking element;

a second coupling face having a set of reverse locking formations adapted for abutting engagement with the at least one reverse locking element to prevent the relative rotation in a reverse direction about the axis; and

a third coupling face that opposes the first coupling face, the third coupling face having a set of forward locking formations, each of the set of forward locking formations being adapted for abutting engagement with one of the forward locking elements to prevent the relative rotation in a forward direction about the axis, wherein the number of forward locking elements is different than the number of reverse locking elements, wherein the number of forward locking formations is different than the number of reverse locking formations, wherein either the forward backlash is a non-zero integer multiple of the reverse backlash or the reverse backlash is a non-zero integer multiple of the forward backlash to prevent the coupling assembly from inadvertently binding in both directions about the axis, wherein the forward pockets are grouped into at least one set and wherein the forward pockets in each set are uniformly angularly spaced.

19. The assembly as claimed in claim 18 , wherein the forward pockets are grouped into two or more sets.

20. A controllable coupling assembly having forward and reverse backlash, the assembly comprising:

a plurality of forward locking elements, each of the forward locking elements having a load-bearing surface;

a plurality of reverse locking elements, each of the reverse locking elements having a load-bearing surface; and

first, second and third coupling members supported for relative rotation about a common rotational axis, the coupling members including:

a first coupling face having a set of forward pockets angularly spaced about the axis, each of the forward pockets receiving one of the forward locking elements and defining a forward load-bearing surface adapted for abutting engagement with the load-bearing surface of its respective forward locking element;

a second coupling face having a set of reverse locking formations, each of the set of reverse locking formations being adapted for abutting engagement with one of the reverse locking elements to prevent the relative rotation in a reverse direction about the axis;

a third coupling face that opposes the first coupling surface, the third coupling face having a set of forward locking formations, each of the set of forward locking formations being adapted for abutting engagement with one of the forward locking elements to prevent the relative rotation in a forward direction about the axis; and

a fourth coupling face that opposes the second coupling face, the fourth coupling face having a set of reverse pockets angularly spaced about the axis, each of the reverse pockets receiving one of the reverse locking elements and defining a reverse load-bearing surface adapted for abutting engagement with a load-bearing surface of its respective reverse locking element wherein the number of forward locking elements is different than the number of reverse locking elements, wherein the number of forward locking formations is different than the number of reverse locking formations and wherein either the forward backlash is a non-zero integer multiple of the reverse backlash or the reverse backlash is a non-zero integer multiple of the forward backlash to prevent the coupling assembly from inadvertently binding in both directions about the axis.

21. The assembly as claimed in claim 20 , wherein the reverse pockets are grouped into at least one set and wherein the reverse pockets in each set are uniformly angularly spaced.