Hydraulic press (a kind of hydraulic press) is a kind of hydraulic press that uses special hydraulic oil as the working medium, uses the hydraulic pump as the power source, and uses the force of the pump to make the hydraulic oil enter the oil cylinder / piston through the hydraulic pipeline. Then there are several groups of mutually matched seals in the oil cylinder / piston. The seals at different positions are different, but they all play the role of sealing, so that the hydraulic oil can not leak. Finally, make the hydraulic oil circulate in the oil tank through the check valve, and make the oil cylinder / piston cycle to do work, so as to complete a certain mechanical action as a kind of machinery of productivity.