A motorized drive device for an occultation or solar protection device, the motorized drive device being provided for moving at least one screen along a rail of the occultation or solar protection device according to a sliding movement, the motorized drive device comprising at least: - a housing, - an electric motor, - a drive wheel, the drive wheel being configured to be rotated by means of the electric motor and to be supported on at least one running surface of the rail, so as to move the motorized drive device along the rail in a direction of movement, - a first holding device, the first holding device comprising at least a first guide wheel, the first guide wheel being configured to be supported on a first running track of the rail, - a second holding device, the second holding device comprising at least a first guide wheel, the first guide wheel being configured to be supported on the first running track of the rail, - a first elastic return element, and - a drive unit, the drive unit being configured to be housed within the housing, in an assembled configuration of the motorized drive device, the drive unit comprising at least: - a casing, - the electric motor, and - the drive wheel, the first elastic return element being configured to interact, on one hand, with the housing and, on the other hand, with the casing, the drive wheel being configured to be supported on the running surface of the rail, by means of the first elastic return element, in an assembled configuration of the occultation or solar protection device, the casing being configured to be inclined inside the housing, relative to a median plane of the housing, when the electric motor is electrically activated, characterized in that the motorized drive device further comprises at least: - a first switching mechanism (41, 42), the first switching mechanism (41, 42) being configured to drive at least the first guide wheel of the first holding device between a first position and a second position, and vice versa, in that the first position of the first guide wheel of the first holding device is a position in which the motorized drive device is configured to be mounted relative to the rail, in that the second position of the first guide wheel of the first holding device is a position in which the motorized drive device is configured to be dismounted relative to the rail, and in that, in the first position of the first switching mechanism (41, 42) and when the electric motor is electrically activated, the drive wheel is supported on the running surface of the rail, by means of the first elastic return element supported on a wall support arranged in the housing and is rotated, around the axis of rotation, by means of the electric motor. - a housing, - an electric motor, - a drive wheel, the drive wheel being configured to be rotated by means of the electric motor and to be supported on at least one running surface of the rail, so as to move the motorized drive device along the rail in a direction of movement, - a first holding device, the first holding device comprising at least a first guide wheel, the first guide wheel being configured to be supported on a first running track of the rail, - a second holding device, the second holding device comprising at least a first guide wheel, the first guide wheel being configured to be supported on the first running track of the rail, - a first elastic return element, and - a drive unit, the drive unit being configured to be housed within the housing, in an assembled configuration of the motorized drive device, the drive unit comprising at least: - a casing, - the electric motor, and - the drive wheel, - a casing, - the electric motor, and - the drive wheel, the first elastic return element being configured to interact, on one hand, with the housing and, on the other hand, with the casing, the drive wheel being configured to be supported on the running surface of the rail, by means of the first elastic return element, in an assembled configuration of the occultation or solar protection device, the casing being configured to be inclined inside the housing, relative to a median plane of the housing, when the electric motor is electrically activated, characterized in that the motorized drive device further comprises at least: - a first switching mechanism (41, 42), the first switching mechanism (41, 42) being configured to drive at least the first guide wheel of the first holding device between a first position and a second position, and vice versa, - a first switching mechanism (41, 42), the first switching mechanism (41, 42) being configured to drive at least the first guide wheel of the first holding device between a first position and a second position, and vice versa, in that the first position of the first guide wheel of the first holding device is a position in which the motorized drive device is configured to be mounted relative to the rail, in that the second position of the first guide wheel of the first holding device is a position in which the motorized drive device is configured to be dismounted relative to the rail, and in that, in the first position of the first switching mechanism (41, 42) and when the electric motor is electrically activated, the drive wheel is supported on the running surface of the rail, by means of the first elastic return element supported on a wall support arranged in the housing and is rotated, around the axis of rotation, by means of the electric motor.