Jack is the simplest lifting equipment with a small lifting height (less than 1m). It has two types: mechanical and hydraulic. There are two types of mechanical jacks: rack type and screw type. Due to their small lifting capacity, they are laborious to operate and are generally only used for mechanical maintenance work and are not applicable during bridge repair. Hydraulic jacks have a compact structure, stable operation, and self-locking function, making them widely used. Its disadvantages are limited lifting height and slow lifting speed. Jacks are mainly used in factories, mines, transportation and other departments as vehicle repairs and other lifting and support work. Its structure is lightweight, sturdy, flexible and reliable, and can be carried and operated by one person. As a widely used tool, the jack is cast with the highest quality materials, ensuring the quality and service life of the jack. Today, ATO will introduce the basic classification of jacks.