The system under investigation is the hydraulically driven large-scale combined legged and wheeled vehicle ALDURO. It combines the advantages of a walking machine with the stability and speed of a wheeled vehicle. It is able to move over rugged terrain. Due to the kinematic constraints arising at the wheel-ground contact, ALDURO is a nonholonomic system which includes several closed kinematic loops. The mobility of the system in uneven terrain is investigated using a simplified model.