In a steel plant, slag tank vehicles are the key equipment for transferring slags. In the No.3 Steel Plant of Wuhan Steel Works, spontaneous turning failure and braking failure often occur with the 35t slag tank vehicle imported from Spain. To solve these problems and assure production safety, it was decided to add an oil pump, increase the oil pressure in the related circuits properly and to add an energy reservoir. Since these measures were put into operation, the turning failure and braking failure were eradicated thoroughly. It is shown in practice that the expected results have been achieved.