import json

class Suspension:
    traverse_speed = 0

    def fill_fields(self, json_response):
        suspension_data = json_response["suspension"]
        self.traverse_speed = suspension_data["traverse_speed"]

    def __str__(self):
        result = """
Корпус:
Скорость вращения - {} гр/с""".format(self.traverse_speed)
        return result

if __name__ == "__main__":
    file = "test/localdump.json"
    with open(file) as data_file:
        data = json.load(data_file)

    a = Suspension()
    a.fill_fields(data["data"]["305"]["default_profile"])
    print(a)