The cause of leaking and external leakage in the hydraulic cylinder: one is the piston rod (or plunger) appearance worn or pulled out the groove mark, can be repaired by electroplating or metal brush plating. The second is the internal and external wear of the guide sleeve, because of the low price of guiding sleeve, the individual is changing. Thirdly, the hydraulic cylinder body itself is worn out or pulled out deep groove, or in the cylinder body wall to emerge cavitation area, which can also be used to repair brush plating process. The fourth is the piston seal aprons wear, at this time change can. Coil punch inside leak and leakage will make the hydraulic cylinder active shrink, to the hydraulic cylinder mounted on the car has 3 kinds of review way: First, using a hundred meters, the magnetic table is adsorbed on the hydraulic cylinder piston rod, hands offset in the end of the cylinder, inspection hands The change value of the engine flameout 15min (including the above two ways) before and after the initiator is the return of the hydraulic cylinder; the second is the protruding piston rod with butter on a piece of paper, measuring the upper end of the paper to the hydraulic cylinder at the interval of change, that is, the hydraulic cylinder shrinkage The third is to use a loose and locked rubber plate to lock on the piston rod, the measurement method and the use of paper in the same way. The above detection method is also the way to determine whether the hydraulic cylinder can leak and its level. According to the shrinkage of the hydraulic cylinder measured, it can accurately calculate the wear level of the piston seals and the use of the equipment time, if the use of a short time, it can be determined that the seal is due to demolition of improper destruction of the way; This is very useful for correcting the method of disassembly and judging the discharge level of the hydraulic cylinder.