U-Rings

U-Ring Seals (also called U-seals, U-cup, and symmetrical seals) are multipurpose seals that can be fitted either on a rod or a piston cylinder and have a unique “U” shaped profile. Both the outer and inner sealing lips are designed to optimise both rod and piston sealing applications.

Why U-rings?

U-rings are interchangeable between rod and piston applications. They have high sealing properties and excellent resistance to abrasion, friction, and wear. Its use is recommended with hydraulic oils, mineral oil-based hydraulic fluids, lubrication oils and HFA/ HFB fluids.

The outside has a static lip seal that functions against mating surfaces that have no relative motion between each other. The inside of the U-Seal has a dynamic lip seal that is used for when there is motion between surfaces. The “U” shape energises the sealing lips as the application pressure increases. 

Loaded or unloaded?

Loaded
A loaded U-ring is loaded with an O-ring or sometimes a quad ring, between two lips of a seal, and helps increase the sealing force at low pressures while blocking or separating fluid in reciprocating motion applications.

The loaded U-Cup is when you add a 'loader or energiser' to a lip seal, it becomes a squeeze seal. This provides high sealing force at low pressure. As the system pressure increases, the lip loading also increases, automatically compensating for the higher pressure while maintaining a positive seal

Unloaded 
With an unloaded U-ring, the seal is simply not loaded with an O-ring or a quad ring inside.