Chassis and Shoulders of Polar Lunar Robot  Polaris is a rover
specialized for drilling lunar ice. The chassis (Pic1) is an ‘H’
shaped carbon fiber structure to which aluminum radiator,
baseplate and torque tube are mounted. Four rocker arms provide
a passive suspension via chains, sprockets and transverse torque
tube. To test this setup, the torque tube, all four shoulder
assemblies, and chains were fitted and tested for motion.  Each
main shaft has a large sprocket which is used to link the
rotation of the two shoulders on that side of the rover. The two
larger shoulders have additional shafts and sprockets for chain
tensioning and the differencing mechanism.  The two shafts
located towards the bottom relate to the passive averaging
suspension. The larger one, known as the differencing shaft,
contains a sprocket and is connected to the torque tube. The
other shaft is an idler that redirects the chain loop to
increase tooth engagement on the differencing shaft sprocket.
The differencing shafts on opposing sh