Abstract: The problem of tire deviation often occurs during the use of domestic frame type stents, that is, after a period of use, the four tires on the rear frame are not evenly worn, and one or two rear tires on both sides are more worn than the rest of the tires. Through tracking and observation, the rear tire will be temporarily locked or reversed under the operating conditions of the loose valve in the vehicle running, resulting in non-rolling friction, resulting in abnormal wear. Based on the operation mechanism of the closed system with single pump and two motors, the forming process of hydraulic braking force is analyzed，at the same time, combining with the mechanical structure of the vehicle, it is further demonstrated that the adhesion of the rear is less than the adhesion of the front tire in the process of vehicle loose throttle, so the back tire easily reverses and causes abnormal wear, thus forming partial grinding. By adding controlled overflow valve in the loop, the closed type walking system is optimized. After the installation is applied for half a year, the partial grinding phenomenon can be eliminated, the service life of the tire is improved effectively, and the running cost of the whole vehicle is reduced.