DBH radial shaft seals: replacement by d, D and h size
A radial shaft seal (also called an oil seal) keeps the grease or oil of a bearing from escaping out of the housing, and keeps dirt, water or dust from getting in from outside to the bearing. It is a small, cheap part compared to what it protects, but a badly chosen or worn seal is one of the most common causes of a bearing washing out and failing early.
The designation of a DBH seal describes three dimensions and a design code: the shaft diameter (d, where the rotating shaft passes through), the housing diameter (D, where the seal seats against the housing or the bearing housing) and the height or width (h). The design code that follows the number —variants such as the ones in our catalog— identifies the type of sealing lip and the elastomer material. To order the correct replacement, these three dimensions are enough: if you have the old seal, measure it with a caliper before discarding it.
They are used on rotating shaft bearings in every kind of machine: electric motors, gear reducers, centrifugal pumps, gearboxes, industrial fans and agricultural equipment. In Argentina it is one of the most requested replacement parts in plant maintenance, because it degrades with use —the lip wears, the elastomer dries out with heat— even when the bearing it protects is still in good condition.
When choosing a seal, it pays to look beyond the dimensions: the peripheral speed of the shaft (the higher the speed, the more heat the lip friction generates), the working temperature, which defines the elastomer material, and whether the environment has dust or pressurized liquids, where a double-lip design is preferable. Installation matters as much as the choice: a seal fitted out of square or with the lip damaged by the shaft edge fails within a few weeks.
Seals are made to the same three dimensions by several brands and origins, so it is common to find an equivalent from another manufacturer for a size that is temporarily unavailable. What does not change between brands is the size: if the shaft and the housing match, the seal performs the same function regardless of who made it.
If you have the old seal or the bearing that needs sealing, send us the three dimensions —or a photo with the caliper in place— via WhatsApp and we will confirm the part number and the available equivalent. MR Accesorios Industriales has the most requested DBH designs on the Argentine market listed.
