Vehicle comprising a controlled vertical position chassis in order to be moved between a high running position and a low position in which the chassis is supported on the ground , the vehicle also including a plurality of wheels (R1-R4), and, associated with each wheel: - a wheel-bearing suspension arm , the arm being pivotably mounted on the chassis ; - a suspension arm actuator , arranged between the suspension arm and the chassis , the actuator making it possible to control an angular position of the arm relative to the chassis, in order to vary the vertical position of the chassis, characterised in that it comprises: - a safety device capable of limiting the accidental lowering of the chassis , the device being capable of adopting, on the one hand, an active state in which it makes it possible to limit the rotation of the suspension arm , in a first direction (S1) leading to the lowering of the chassis, to a safety position of this arm, and, on the other hand, an inactive state in which it allows the rotation of this arm in the first direction (S1), beyond the safety position, the safety device comprises a jack having a cylinder mounted on the chassis and a piston mounted on the suspension arm , or vice versa, the jack defining a first chamber communicating with a first and a second fluid passage through the cylinder , spaced apart from one another in a direction of sliding of the piston in the cylinder so that the second passage is located as close as possible to a bottom of the first chamber defined by the cylinder, the second passage communicating with a first fluid duct provided with a safety valve adopting: - an open position in the inactive state of the safety device , so as to allow the fluid to be discharged from the first chamber through the second passage , when the piston moves toward the bottom of the first chamber due to the rotation of the suspension arm in said first direction (S1); and - a closed position in the active state of the safety device , so that when the piston moves toward the bottom of the first chamber, due to the rotation of the suspension arm dans in said first direction (S1), the piston is locked in a safety position at a distance from the bottom of the first chamber, in which position the fluid is compressed between the piston head and the safety valve . - a wheel-bearing suspension arm , the arm being pivotably mounted on the chassis ; - a suspension arm actuator , arranged between the suspension arm and the chassis , the actuator making it possible to control an angular position of the arm relative to the chassis, in order to vary the vertical position of the chassis, - a safety device capable of limiting the accidental lowering of the chassis , the device being capable of adopting, on the one hand, an active state in which it makes it possible to limit the rotation of the suspension arm , in a first direction (S1) leading to the lowering of the chassis, to a safety position of this arm, and, on the other hand, an inactive state in which it allows the rotation of this arm in the first direction (S1), beyond the safety position, - an open position in the inactive state of the safety device , so as to allow the fluid to be discharged from the first chamber through the second passage , when the piston moves toward the bottom of the first chamber due to the rotation of the suspension arm in said first direction (S1); and - a closed position in the active state of the safety device , so that when the piston moves toward the bottom of the first chamber, due to the rotation of the suspension arm dans in said first direction (S1), the piston is locked in a safety position at a distance from the bottom of the first chamber, in which position the fluid is compressed between the piston head and the safety valve . <EOS>