"...The MER provides a separate RB (Rocker-Bogie)system for the left and right wheels. Each RB consists of a forward and aft bogie, to which are attached corresponding forward and aft bogie wheel struts. The end of each wheel strut provides an attachment point for a drive motor and wheel assembly. The aft bogie structure slides into the forward bogie's structural cavity, and is secured to the FB by way of a square bolt, which can be inserted into one of four available positioning holes. The aft rocker arm is affixed to the forward bogie, near the AB/FB attach point through a hinge and actuator assembly. A U shaped adapter bracket fits onto the other end of the AR. The bracket holds a structural member that provides a mount for the Rocker Deployment Actuator, which permits the forward bogie that it's attached to to be rotated around the longitudinal axis of the rover. The end of the forward bogie has an attach point for a drive motor and wheel assembly..."