U-cup BA: page 19
BA seals seal rotating shafts in hydraulic pumps, motors, and gearboxes — not rods, but shafts that rotate continuously. They can be found in gear pumps, wheel drive motors, gearboxes, and agricultural equipment. Their role is twofold: they keep the oil inside and block dust and water from the outside. The choice of material — NBR or FKM — depends on the fluid and temperature, two factors that determine the actual service life. Complete catalogs by diameter, shaft type, and material are available at hydsealstore.ro, with compatibility recommendations for the main pump brands.
Properties and Role of BA Seals in Rotary Sealing
The construction is simple but effective: a rigid metal ring fixed in the housing by interference and a flexible lip with an internal spiral spring that maintains contact with the shaft. The spring compensates for wear over time, so the sealing force remains constant for a long time after installation, even after the lip has become thinner. Available in NBR (up to +150°C, inexpensive and versatile for most mineral oils) and FKM (up to +200°C, resistant to gasoline, synthetic oils, and a much wider range of chemicals). For equipment operating continuously, FKM quickly pays for itself. The pump sealing system also includes other components from the range of hydraulic seals, including static seals for pump covers and housings.
Areas of Use and Resistance to Aggressive Environments
BA seals are found in hydraulic gear and piston pumps, transmission drive motors, speed reducers, drive axles, power steering systems, and tractors. When the fluid is synthetic or the temperature exceeds +120°C, FKM is the only correct choice — NBR fails quickly under these conditions, and the lip hardens within a week or two, resulting in immediate leakage. Even for older equipment, upgrading to FKM during the first overhaul is a minor cost with a noticeable impact on cylinder service life. Complete system protection also includes hydraulic wipers on cylinders operated by the pump, not just shaft sealing.
Selection Criteria and the Importance of Correct Dimensions
You need the inner diameter (= shaft diameter), outer diameter (= housing bore), and seal width. You choose the material according to the fluid in the system and the maximum operating temperature reached during continuous operation, not just at peak levels. The shaft must be clean and free of scratches during installation — any defect on the surface quickly wears the lip and shortens the service life of the new seal to a few hundred hours. If the shaft is already marked, a seal with a different width moves the lip to an undamaged area. Other profiles are listed in the range of hydraulic seals, with double versions or versions with a deflector for environments with dust and water.
Advantages of Purchasing BA Seals from Hydraulic Seals Store
For sealing rotating shafts, Hydraulic Seals Store offers BA seals in material variants adapted to different applications. These seals are used in pumps, motors, gearboxes, and other equipment in which the shaft rotates continuously. The choice between NBR and FKM mainly depends on the fluid used and the temperature at which the equipment operates.
When ordering, it is good to have the shaft diameter, housing diameter, and seal width at hand. These dimensions help avoid making the wrong choice, especially when there are several variants with similar dimensions. If you need help identifying the BA seal, our team can provide you with technical support.