Overload protector is equipped in press machines to check the hydraulic pressure of cylinder inside the slider. The hydraulic pressure of cylinder will be released immediately within 3/1000 seconds. When overloaded, in order to protect the press and die, the press stops working immediately after receiving the signal from limit switch. After overloading occurs, the air will drive the hydraulic pump to supplement normal working pressure immediately and the press works normally. It consists of pressure control valve inside the overload protector, which adjusts hydraulic pressure automatically and eliminate the impact of rising pressure in pressing process.