A hydraulic jack is a jack that uses a plunger or a hydraulic cylinder as a rigid jack to lift heavy objects. Simple structure, lightweight, easy to carry and easy to move.
The hydraulic jack should generally use special hydraulic oil, and the hydraulic oil should have the following properties: (1) Good lubrication performance; (2) Good purity and fewer impurities; (3) Suitable viscosity and good viscosity-temperature characteristics; (4) Good anti-foam, anti-emulsification and anti-rust properties, and low corrosiveness; (5) Good stability to heat, oxidation and hydrolysis, and long service life; (6) Good compatibility with metals and seal materials used in hydraulic systems; (7) The specific heat and heat transfer coefficients are large, the volume expansion coefficient is small, the flashpoint and ignition point are high, and the flow point and freezing point are low.