Abstract: A utility vehicle, such as a grape harvester (1), comprises a straddling frame (2), supported at its front and rear ends by double-acting hydraulic cylinders (17, 18 and 23, 24), which can be extended or retracted for levelling the frame (2). During horizontal or uphill travel, the rear cylinders (23, 24) are blocked for providing the vehicle (1) with a fixed rear axle (55), while the front cylinders (16, 17) are hydraulically interconnected in order to let them extend or retract in opposition to each other for providing the vehicle (1) with an oscillating front axle (56). During downhill travel the front cylinders (17, 18) are blocked for fixing said front axle (56) to the frame (2) and the rear cylinders (23, 24) are hydraulically interconnected for letting the rear axle (55) oscillate to the frame (2). The rear and front oscillation is controlled by an inclination sensor (91).