NSK6011DDUC3Deep Groove Ball Bearing 55x90x18 mm, Two Contact Rubber Seals, C3 Clearance, Sealed for Life, 2 Pcs

Product Description

What this part is

An NSK 6011DDUC3 single-row deep groove ball bearing — 55 mm bore, 90 mm outside diameter, 18 mm width — with contact rubber seals on both faces and C3 internal clearance. It arrives grease filled and sealed for life, so it is fitted and run without an external lubrication supply.

Decoding the designation

6011 – single-row deep groove ball bearing, 55 mm bore, 90 mm OD, 18 mm width
DDU – two contact rubber seals, one on each face; the NSK equivalent of a 2RS designation
C3 – internal clearance greater than normal

What these specs mean in practice

Contact seals rub lightly on the inner ring land, which excludes dust, water and washdown spray far better than a steel shield and keeps the factory grease charge in place. In a dirty position the seal decides bearing life, which is why a DDU version outlasts a ZZ or an open bearing in the same duty. The trade-off is a little running torque and a lower speed ceiling than the shielded or open version. C3 clearance is greater than normal, which suits a tight interference fit on the shaft, a warm running housing, or a temperature difference between inner and outer ring — all conditions that consume clearance once the bearing is running.

Published specifications

Bore: 55 mm (2.1654 in)
Outside diameter: 90 mm (3.5433 in)
Width: 18 mm (0.7087 in)
Rows: 1
Rolling elements: balls
Closure: two contact rubber seals
Internal clearance: C3 (greater than normal)
Lubrication: grease filled, sealed for life
Snap ring: not fitted
Material: through-hardened bearing steel

Quantity and configuration

Sold as 2 Pcs. Two complete bearings, each sealed on both faces. No snap rings, spacers or lock nuts are included.

Fitting notes

Mounting force is applied to the ring being fitted so that no load passes through the balls, and the seals are not a press surface. Induction heating suits this diameter, held below the seal and grease temperature limit. No grease charge is needed on installation, and a relubrication port in the housing has no path into the bearing.

Interchange guidance

The direct equivalent is a double contact-sealed 6011 with C3 clearance in the 55 x 90 x 18 mm envelope: SKF 6011-2RS1/C3, FAG 6011-2RSR-C3, NTN 6011LLUC3, Koyo 6011-2RSC3, Timken 6011-2RS-C3. A shielded 6011ZZ or 6011-2Z shares the envelope but is non-contact and seals less effectively, and a CN-clearance version of the same bearing behaves differently under a tight shaft fit, so those are related versions rather than drop-in equivalents.