Why do you need to develop a controllable dowty retarder？

As we all know, ordinary dowty retarder do not need external control and energy, so they have many advantages, such as energy saving, flexible layout, reliable work and so on. However, when adopting the full retarder speed control system, the dowty retarder group will brake and decelerate all the rolling vehicles higher than the critical speed, which makes the large group of vehicles in operation, especially the large group of empty vehicles, decelerate quickly at the head of the shunting yard, resulting in the long running time of the large group of vehicles, and the turnout can not be quickly converted, thus affecting the rolling of the next coupler, directly affecting the efficiency of the hump operation. How to make dowty retarder have the function of "let the head stop the tail" like the dowty retarder, so as to realize that the head of large group of vehicles, especially large group of empty vehicles, does not brake first when passing through the top group, so that it can quickly pass through the turnout area, and then brake and decelerate the second half of vehicles as required. This requires the development of a "controllable dowty retarder" which can be automatically controlled by a computer. The "computer controlled dowty retarder speed control system" composed of it can realize the real-time control of the rolling car, that is, the "let the head block the tail" control can be implemented for large groups of cars according to the operation needs, so as to greatly improve the speed control effect and transportation efficiency of the system.