Stick Ram Seals Hydraulic Cylinder Seal Kit 215-9990 525-3511 2159990 5253511 Fits for CaterpillarThe meaning of oil seal is: oil seal is a mechanical component used to seal oil (oil is the most common liquid substance in the transmission system, and also generally refers to the general liquid substance), which isolates the parts that need to be lubricated in the transmission parts from the output parts, Do not allow the oil to leak. Its functions are as follows: 1. Prevent oil from leaking through the rubber oil seal cover and oil seal washer; 2. Restore the elasticity of the rubber oil seal and protect the elasticity of the oil seal and O-ring. 3. Prevent oil from being sucked into the combustion chamber, prevent and reduce smoke exhaust. 4. Reduce engine noise and improve engine compression ratio. 5. Extend the service life of the engine and prevent expensive maintenance costs. 6. Effectively suppress the oil leakage of the steering gear. 215-9990: 095-1726: SEAL-O-RING 096-5609: RING 105-7262: Wear Ring 128-9266: SEAL-BUFFER 165-9291: SEAL-LIP TYP 170-9865: U-Cup Seal 6I-6785: RING SEAL 7Y-4941: RING 7Y-4945: RING 9X-3607: SEAL AS 525-3511: 095-1726: SEAL-O-RING 096-5609: RING 105-7262: Cat® Wear Ring 128-9266: SEAL-BUFFER 165-9291: SEAL-LIP TYP 170-9865: Cat® U-Cup Seal 506-2322: SEAL AS 6I-6785: RING SEAL 7Y-4941: RING 7Y-4945: RING