Multiple-part modular shaft

A modular shaft assembly, comprising:

• a main shaft extending a length from a first end of the main shaft to a second end of the main shaft, wherein the main shaft further comprises:
• a longitudinal axis extending along the length and defining a rotational center of the main shaft;
• and
• a modular interconnection interface arranged at the second end of the main shaft, the modular interconnection interface comprising a rotational alignment feature that is rotationally fixed relative to the longitudinal axis, wherein the modular interconnection interface engages with an eccentric shaft selected from a plurality of eccentric shafts, wherein each eccentric shaft of the plurality of eccentric shafts comprises:
• a first body portion arranged at a first end of the eccentric shaft;
• and
• a second body portion arranged at a second end of the eccentric shaft, wherein the second body portion is eccentrically attached to the first body portion by an eccentric offset distance, and wherein the eccentric offset distance defines an eccentricity of the eccentric shaft relative to the longitudinal axis.

A crankshaft, comprising:

• a main shaft extending a first length along a first longitudinal axis from a first end of the main shaft to a second end of the main shaft, wherein the first end is arranged opposite the second end;
• and
• an eccentric shaft that extends a second length along a second longitudinal axis from a first end of the eccentric shaft to a second end of the eccentric shaft, wherein the eccentric shaft further comprises:
• a rim centered with the second longitudinal axis of the eccentric shaft;
• a first protrusion extending from the rim in a direction toward the first end of the eccentric shaft, wherein the first protrusion is concentric with the rim;
• and
• a second protrusion extending from the rim in a direction along an eccentric axis toward the second end of the eccentric shaft, wherein the eccentric axis is arranged parallel to and offset a distance from the second longitudinal axis, and wherein the second protrusion is arranged eccentric to the first protrusion;
• wherein the eccentric shaft is selectively attached to the main shaft at an interface between the first protrusion and the second end of the main shaft, and wherein the eccentric shaft is rotationally fixed at a first eccentricity relative to the main shaft via a torque transmitting component of the interface.