Shaft coupling

A shaft coupling system comprising:

• a first shaft including a movable disc that is engageable by a second shaft to
• retain the second shaft with the first shaft based on a first movement of the second shaft relative to the first shaft, and
• release the second shaft from the first shaft based on a second movement of the second shaft relative to the first shaft,
• wherein the second movement is generally opposite of the first movement,
• wherein the disc includes an elongated external protrusion that includes a semi-cylindrical cross-section,
• wherein the protrusion is elongated along a central longitudinal axis of the disc,
• wherein the protrusion is engageable with a complementary internal groove of the first shaft to limit rotation of the disc, and
• wherein the internal groove is elongated along a central longitudinal axis of the first shaft.

A shaft coupling method comprising:

• engaging a second shaft with a disc of a first shaft by rotating the second shaft in a first direction relative to the first shaft;
• and
• disengaging the second shaft from the first shaft by rotating the second shaft in a second direction relative to the first shaft,
• wherein the second direction is generally opposite to the first direction,
• wherein a spring mounted to the first shaft biases the second shaft towards the first shaft when the second shaft is engaged with the first shaft,
• wherein the disc includes an elongated external protrusion that includes a semi-cylindrical cross-section,
• wherein the protrusion is elongated along a central longitudinal axis of the disc,
• wherein the protrusion is engageable with a complementary internal groove of the first shaft to limit rotation of the disc, and
• wherein the internal groove is elongated along a central longitudinal axis of the first shaft.