In some conditions, four-wheeled high speed mobile robots designed for open-field applications may take off and land badly. In order to avoid this dead-end situation, it is possible to use the mechanical principle of angular momentum conservation for correcting the pitch angle of the vehicle during the ballistic phases of actual jumps. In this study, the mechanical model of pitch control has been verified in laboratory experiments with a prototype of all-terrain AGV called "RobCat". Two series of trials have been realized on a specific test bench in which RobCat was hanged on a transversal axis passing through its CoM. In each series, RobCat was equipped either with its original hollow rubber tyres or with solid wheels having equivalent inertial parameters. The results of these experiments validated the mechanical model of angular momentum conservation of RobCat during an airborne phase and the feasibility of controlling RobCat's orientation around its pitch axis by accelerating or braking its wheels. The conclusions of this experimental study are highly encouraging for building agile mobile robots able to roll at high velocities on irregular grounds and that will combine the speed of aerial drones with the large autonomy and interaction capacity of terrestrial robots.