NOVELTY - The device (1) has a steel support (4) including a front portion (4a) and a rear portion (4b) articulated in rotation with each other. Each portion is connected to a structural element i.e. longeron (3), by connection angles (5a, 5b) that are assembled with each other by deformation of the structural element. The portions respectively define ascending and descending ramps with respect to a direction from front to rear of a vehicle at a deformed state of the structural element. Each ramp defines a top line on which a rigid element i.e. energy supply battery, (2) is slid.    USE - Device for shifting a rigid element i.e. energy supply battery, mounted on a structural element i.e. longeron, of a motor vehicle (all claimed) from an initial position to a raised position. Can also be used for shifting a water reservoir of a cooling circuit of a combustion engine or a strong inertia type spare wheel in an engine compartment.    ADVANTAGE - The shifting device shifts the rigid element mounted on the structural element of the motor vehicle from the initial position to the raised position in an easy manner. The shifting device allows the rigid element to assure a passive safety function of the vehicle by shifting the rigid element indexed to the deformation of the structural element of the vehicle. The shifting device permits to raise the rigid element, in case of shock, such that a center of gravity is located above a rotation point, thus fovorizing an amplifier of a braking device to move around a deck of the vehicle, and hence assuring safety of the driver of the vehicle.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a motor vehicle comprising a braking device formed of an actuator connected to a control body.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view illustrating shifting of an energy supply battery with respect to a structural element of a motor vehicle by a shifting device.    Shifting device (1)    Energy supply battery (2)    Longeron (3)    Support (4)    Front portion (4a)    Rear portion (4b)    Connection angles (5a, 5b)