Flexible rotational shaft

A flexible drive shaft comprising:

• a first shaft portion extending along a rotational axis;
• a second shaft portion extending along the rotational axis;
• a first angular displacement coupling engaged to the first shaft portion;
• a second angular displacement coupling engaged to the second shaft portion;
• and
• an axial displacement coupling including an outer periphery, a first wall engaged to and extending radially between the first shaft portion and the outer periphery, a second wall spaced axially from the first wall and engaged to and extending radially between the second shaft portion and the outer periphery, wherein the first and second walls are resiliently flexible to facilitate axial displacement between the first and second shaft portions, and the first wall is spaced axially from the first angular displacement coupling by the first shaft portion and the second wall is spaced axially from the second angular displacement coupling by the second shaft portion, wherein the first angular displacement coupling, the second angular displacement coupling, and the axial displacement coupling are bellows, and
• wherein the axial displacement coupling has greater axial compliancy than the first and second angular displacement couplings.

A flexible drive shaft comprising:

• a first angular displacement coupling;
• a second angular displacement coupling;
• an axial displacement coupling;
• a first shaft portion attached to and extending between the first angular displacement coupling and the axial displacement coupling;
• and
• a second shaft portion attached to and extending between the axial displacement coupling and the second angular displacement coupling, wherein the first and second shaft portions extend along a rotational axis and the first shaft portion is spaced axially from the second shaft portion by the axial displacement coupling, wherein the first angular displacement coupling, the second angular displacement coupling, and the axial displacement coupling are each bellows, and wherein an outer radius of the axial displacement coupling is greater than outer radii of the first and second angular displacement couplings.