SKF hydraulic seals: profiles, sizes and codes

The initial letters name the profile of the seal and, with it, its function in the cylinder: CUT 50X39X4.2 and GH 25X17.5X3.2-AD1 are different profiles, each with three dimensions separated by X. ZW 25X32 carries two. Which diameter comes first depends on the profile, so dimensions are not compared across families.

In DTW-25X33X5-J2G the dimensions are visible, and the final block distinguishes the material. DSW-625-J2G, by contrast, carries a number that is not a direct dimension in millimetres. In every case the final block is part of the reference: the same profile exists in compounds for different fluids and temperatures.

When a cylinder leaks, the usual practice is to replace the whole set rather than a single seal: all of them have worked the same hours, and dismantling twice costs more than the spare part. When dismantling, note which groove each part was in and which way the lip faced; a single-acting seal fitted the wrong way round does not seal.

Look at the rod and the bore too. A lengthwise scratch, a dent or corrosion cuts the new seal in the first cycles. And check the guides: if they are worn, the rod runs tilted and loads the seal on one side. The fluid and the temperature define the material, which is worth keeping.

Send us the codes of each seal and the quantity. Without codes, give us the rod diameter, the bore diameter and the dimensions of each groove: bottom diameter, width and depth. State the working pressure, the fluid, the temperature and whether the cylinder is single or double acting. A photo of the removed seals, laid out as they were fitted, helps recognize the profiles.