VALVE GP-SOLENOID 3482302 - Caterpillar

Illustration 1 g00812656
Damaged U-Cup SealThe U-Cup Seal will be deformed into a thin band of material, as shown. This damaged U-Cup Seal appears to be melted due to excessively high temperatures. Extrusion of the U-Cup Seal can occur at any temperature if the pressure is excessively high.
Illustration 2 g00812166
Correct assembly of the buffer seal (1) and backup ring (2) will prevent failure of the U-Cup Seal (3). The backup ring (2) should be assembled toward the rod end of the cylinder, as shown.Note: In some cases, the axial width of the Caterpillar U-Cup Seal may be different from the U-Cup Seal that is being replaced. The Caterpillar U-Cup Seal is correctly sized, based on the rod diameter and the seal groove diameter. The difference in size of the Caterpillar U-Cup Seal will not cause a sealing problem, even though there may be unused space in the seal groove. The U-Cup Seal will not move from the downstream groove wall when the rod is retracting. Pressure will hold the U-Cup Seal against the back of the seal groove. Also, the friction on the outside diameter of the seal is much greater than the friction on the inside diameter, which will also keep the seal firmly seated in the back of the seal groove. Because of these factors, the U-Cup Seal will not touch the upstream side of the seal groove. Therefore, the difference in the axial width between the U-Cup Seal and the seal groove is not a factor in providing good sealing.