Thin Section Bearings

Thin Section Bearing Seals and Shields

Most commonly, Silverthin Thin Section Bearings are available in an ‘open’ configuration, meaning that the balls and cage are readily visible and there are no seals or other closure components. However, in some applications the customer may desire a seal or some other closure method. Most Silverthin Thin Section Bearings that are ‘open’ can have seals added to them. Please contact the Silverthin Engineering Team to discuss available options for your specific application.

Types of Enclosures


Silverthin offers a standard sealed bearing prefixed by the letter ‘J’, such as JHSA, JHSU, JA, JB, JD, and JG

These bearings are sealed using a Buna-N rubber seal reinforced by a steel backing in the configuration shown below. This is a positive contact seal, meaning that the Buna-N exterior lip (fixed to the outer ring of the bearing) slides on a riding surface on the inner ring of the bearing. The positive contact seal will add torque to the application. (Inch Series: Maximum torque values can be found on page X in the tolerance tables OR Metric Seres: Please contact your Silverthin Engineering Team for torque values.)

Steel backed Buna-N rubber seal

Non-Contact Shield

Sometimes seals will add more torque than is desirable in an application. In those cases, a non-contact shield provides a good option. This is typically a steel ring attached to the outer ring of the bearing that does not contact the inner ring of the bearing, thus adding no additional torque. It may also be like the positive contact seal shown above, with the lip size reduced or the seal land relieved to prevent positive contact. However, the sealing capability is limited, and dust and moisture can access the bearing, but will not add additional torque to that of an ‘open’ bearing. A shielded configuration is shown below. Please contact the Silverthin Engineering Team to discuss if this is a viable option for your application.

Non-contact shield

PTFE Coated Fiberglass Tape Seal

Another unique option offered by Silverthin is a PTFE Coated Fiberglass Tape seal, as shown in the figure below. In this option the seal ‘floats’ in a labyrinth groove in the inner and outer ring. This version adds virtually no additional torque but offers better sealing and grease retention than a shield. Please contact the Silverthin Engineering Team to discuss if this option is right for your application.

PTFE coated fiberglass seal

Note that all Sealed, Shielded, and enclosed bearings will be lubricated at the factory. Standard lubrication is a MIL-G-81322 general purpose grease. Other lubricants are available, please contact Silverthin Engineering to discuss your application requirements for lubrication type and fill.