A quasi self-contained system for electric energy storage and power supply intended to be installed on a bogie of the type which comprises an axle (5, 7) and a chassis to provide an electric tractive or braking force to the axle comprising: - 1) at least one energy storage module having the capacity to receive energy, to accumulate it during a non-zero time and to release it on demand in electric form; - 2) at least one electric converter converting the electric energy supplied/absorbed by the energy storage module with a voltage and a current adapted to the energy supply/recovery from the motor/generator unit; - 3) at least one motor/generator unit transforming the electric energy into mechanical energy and vice versa; and - 4) one controller which generates the commands and provides the control signals to the various components of the system according to the information received from various sensors and interfaces, with the energy storage module accumulating or releasing energy to the electric converter, with the electric converter transferring such energy between the energy storage module and the motor/generator unit, with the motor/generator unit transforming the electric energy received from or supplied to/by the electric converter into mechanical energy and the controller controlling the transfer of energy between the energy storage module, electric converter and motor/generator unit elements, characterized in that:. the various sensors comprise: - one accelerometer making it possible to identify the acceleration of the bogie axle whereon the system has been installed; with the acceleration information thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to; - one inclinometer making it possible to identify the inclination of the bogie axle whereon the system has been installed; with the information relative to the inclination thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to;. the controller is so configured as to: - apply and very gradually increase the tractive force produced by the motor/generator unit if the information relative to the inclination collected by the controller is null or positive when the information relative to the acceleration collected by the controller is positive. - 1) at least one energy storage module having the capacity to receive energy, to accumulate it during a non-zero time and to release it on demand in electric form; - 2) at least one electric converter converting the electric energy supplied/absorbed by the energy storage module with a voltage and a current adapted to the energy supply/recovery from the motor/generator unit; - 3) at least one motor/generator unit transforming the electric energy into mechanical energy and vice versa; and - 4) one controller which generates the commands and provides the control signals to the various components of the system according to the information received from various sensors and interfaces,. the various sensors comprise: - one accelerometer making it possible to identify the acceleration of the bogie axle whereon the system has been installed; with the acceleration information thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to; - one inclinometer making it possible to identify the inclination of the bogie axle whereon the system has been installed; with the information relative to the inclination thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to; - one accelerometer making it possible to identify the acceleration of the bogie axle whereon the system has been installed; with the acceleration information thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to; - one inclinometer making it possible to identify the inclination of the bogie axle whereon the system has been installed; with the information relative to the inclination thus collected being used by the controller to optimize the transfer of energy during at least one of the traction, braking and headway operations which said system is subjected to;. the controller is so configured as to: - apply and very gradually increase the tractive force produced by the motor/generator unit if the information relative to the inclination collected by the controller is null or positive when the information relative to the acceleration collected by the controller is positive. - apply and very gradually increase the tractive force produced by the motor/generator unit if the information relative to the inclination collected by the controller is null or positive when the information relative to the acceleration collected by the controller is positive.