Jack is a kind of hoisting height small (less than the most simple 1-m) lifting equipment. It has mechanical and hydraulic pressure type two kinds. Mechanical jacks and rack type and spiral two kinds, because up less weight, operation arduous, generally only used in machinery maintenance work, in the repair process does not apply. The hydraulic jacks compact structure, smooth, have self-locking role, reason is used widely. Its defect is lifting height is limited, hoisting speed. Jack is mainly used in mines, transportation departments as vehicle repair and other lifting, support, etc. The structure to be dexterous strong, agile reliable, one can carry and operation. Jack as a using a wide range of tools, used most the high grade material of casting, guarantee the quality and the service life of jacks.