1、按启动按钮，将200吨四柱液压机工作平台上升；用四根等高的木棍等物，将工作平台牢固的撑住；
2. Remove the bolt between the plunger and the bottom of the platform;
3. Use a smooth flat screwdriver to pry out the oil seal of the hydraulic press, and put the new oil seal into the oil seal groove as it is (pay attention to the downward direction of the oil seal lip);
4. Pull the operating rod by hand to separate the plunger and the platform, and lower the plunger to the bottom of the oil seal;
5. Raise the plunger point to the lip of the oil seal by jog, and hold the inner lip of the oil seal of the 200-ton four-column hydraulic machine around the plunger with a smooth flat screwdriver. Be careful not to damage the inner lip of the oil seal;
6. After confirming that the inner lip of the hydraulic oil seal is intact and restrained to the plunger, press the start button to raise the plunger;
7. Connect the bolt between the plunger and the platform, and remove the four wooden sticks supported.