What is the purpose of dowty retarder?

Dowty retarder are used in hump speed control systems at railway marshalling stations. The domestic production dowty retarder is the Harbin Railway Bureau's deceleration speed regulation system research center, which was established in accordance with the order of the Ministry of Railways and established in the 1970s. After decades of development, the center's products have developed dozens of products such as controllable roofs, parking roofs, and acceleration roofs. Many problems have been solved for the speed regulation system of marshalling stations in China. Formed the most researched and developed hump speed regulation theory.