Abstract: In this thesis, the braking state of a certain tread brake unit and the principle of manual relief is introduced, including the principle and mode of action of the brake cylinder in different states. In view of the current parking brake cylinder with unilateral relief, the disadvantages are analyzed, and the conclusion is drawn that it needs to be reformed. According to the different installation positions around the parking brake cylinder, three schemes of changing unilateral relief to bilateral relief are proposed; then the three schemes are compared and analyzed in detail, including the scope of change, the required space size and the renovation cost. Combined with the actual needs of a project, the proposed transformation scheme is given after comprehensive analysis and comparison, and the scheme is elaborated in detail to provide a reference for the manual mitigation transformation needs of tread brake unit.