CATERPILLAR Swing Motor Seal Repair Kit The reason for hydraulic cylinder pulling? The forms of cylinder pulling injuries are diverse, so the reasons for cylinder pulling are also diverse. Excessive dry friction between the cylinder barrel and piston in general hydraulic cylinders leads to strain on the contact surface. The common reasons are as follows: ① The inner wall of the hydraulic cylinder itself is slightly scratched, causing an increase in oil temperature during daily operation, which accumulates and causes cylinder pulling. ② Improper assembly and manufacturing process can cause foreign objects such as dust particles and iron filings to adhere to the cylinder body, which can cause compression and wear of the cylinder body during operation, resulting in cylinder pulling. ③ Impurities in hydraulic oil mixed into the cylinder barrel, causing cylinder pulling. ④ Due to installation errors, the hydraulic cylinder is subjected to eccentric loads, causing the piston rod to deflect and deform, resulting in cylinder pulling. In summary, the main factors leading to cylinder pulling are the excessive roughness between the inner wall of the cylinder and the piston, as well as the damage to the oil film boundary at the contact point, which damages the inner wall of the cylinder.