def calculate_gear_box_heat(gear_box_efficiency, gear_box_power_out, delta_time
    ):
    """
    Calculates the gear box temperature heat [W].

    :param gear_box_efficiency:
        Gear box efficiency [-].
    :type gear_box_efficiency: float

    :param gear_box_power_out:
        Power at wheels [kW].
    :type gear_box_power_out: float

    :param delta_time:
        Time step [s].
    :type delta_time: float

    :return:
        Gear box heat [W].
    :rtype: float
    """
    if gear_box_efficiency and gear_box_power_out:
        eff = gear_box_efficiency
        return abs(gear_box_power_out) * (1.0 - eff) * 1000.0 * delta_time
    return 0.0
