Scarab's chassis allows it to passively conform to the terrain. The differencing linkage ensures the body is pitch-averaged between the rocker arms.
Scarab's body has three contact points. On either side, the body is connected to the pivot in the rocker arms. On top, the body hangs from the differencing linkage. This linkage runs across the top of the body and also connects to the rocker arms.
Scarab actively controls its roll using the rocker arms. The rocker arms allow Scarab to change the height of each side independantly, thus controlling the roll.
In contrast the pitch is passive, Scarab can not actively control this. Scarab's wheels conform to the terrain, which rotates the rocker arms and swivels the differencing linkage. The linkage is constructed such that the body is forced to move up or down to be exactly the average of the two rocker arms.