The jack is the simplest lifting device with a small lifting height (less than 1m). The steel lifting device is used as the working device. The lifting weight of the lifting object is lifted by the top bracket or the bottom bracket. device. It is divided into mechanical and hydraulic types. Jacks are mainly used in factories, mines, transportation and other departments for vehicle repair and other lifting and support work. The structure is light, sturdy, flexible and reliable, and can be carried and operated by one person. In addition, the scissor jack is used as a wide-ranging tool and is made of high-quality materials to ensure the quality and service life of the jack.

The hydraulic transmission force is large, the speed is slow, and there is oil. The gas transmission speed is fast, clean and low. Repair shop jacks are generally hydraulic, households are mixed, according to their actual conditions and requirements.

The most basic principle on which the hydraulic drive is based is the Pascal principle, that is, the pressure across the liquid is uniform, so that in a balanced system, the pressure exerted on the smaller piston is smaller and the larger piston is applied. The pressure is also relatively large, which keeps the liquid stationary. Therefore, through the transfer of the liquid, different pressures at different ends can be obtained, so that a transformation can be achieved. The hydraulic jacks we often use are using this principle to achieve force transmission.

The environmental conditions of the hydraulic equipment are selected as oil: for example, fire-resistant hydraulic oil should be selected in the vicinity of high-temperature heat source or open flame; in cold regions, oil with high viscosity index, good low-temperature fluidity and low freezing point is required; in open air and other environments with high moisture content袄 Consider using oils with good demulsibility.

Select the oil type according to the oil temperature. Depending on the oil temperature used, different oils should be selected. The viscosity and temperature characteristics and thermal stability of the oil should be considered. When the ambient temperature is high, the viscosity grade of the oil should be properly increased. In the winter, oil with lower viscosity should be used, and in summer, oil with higher viscosity should be used.

Select the oil type and viscosity according to the pressure range used. Generally, the requirement for the lubricity of the oil, that is, the abrasion resistance, increases with the increase of the pressure, so the oil with good abrasion resistance and good pressure should be selected at high pressure.