To do this, the differential arm on the rocker is joined to the front of the right side and to the rear of the left side. With the vehicle folded, the differential behaves as if a very large obstacle is at the right front and another at the left rear. As the vehicle stands, both these obstacle angles decrease and the differential keeps the body parallel to the point where it locks in place. To pull this off, the rocker links must be broken at a point where the front and the back parts rotate through the same angle, which involved putting a kink in the front half of each rocker link to clear the center wheel when folded. Because the rover can stand up without tipping, the instruments on each end are not smashed against the lander bed.
Dry lubricants prevent the vehicle being pasted with congealing oil.
The wheels drives use ball bearings with plastic balls, aluminum races, and no lubrication. An X-type bearing design, large enough for the motor and gears to fit inside, takes all wheel loads and the final stage of the planetary gearing. This type of bearing takes radial, axial, and moment loads, all with a single row of balls. Furthermore, joints had be designed to accommodate the differential expansion over the temperature extremes. In addition, the motors have heaters on them because some lubricant had to be used on the commutators.