The following concept tutorial will be covering Dynamic Constraints for sled or Star Wars pod type rigs.

Anatomy of Concept:

Nulls drive the translation of the spring constraints.
Spring(s) contraint drives geometry movement.





Steps for Creation:

Geometry Construction:

2 cylinders, 1 translated +3 X, 1 translated -3 X
1 cube, tweak as needed, position it along the Z & Y. (see below)




Rigging:

Draw joints and create an IK Rotate Plane Solution for each (see below).



Parent each respective Ik Handle to "its" Cylinder. (see below)



Parent each respective start joint to the "sled" geometry.
Create a null and make it the parent of the "sled" geometry. (see below)