Fafnir311KGDeep Groove Ball Bearing – 55 mm Bore, 120 mm OD, 29 mm Width, Open, Snap Ring Groove and Ring

Product Description

What this part is

Fafnir 311KG, a single-row deep groove ball bearing with a snap ring groove in the outer ring and the retaining ring fitted. Bore Diameter: 55 mm. Outside Diameter: 120 mm. Overall Width: 29 mm. Rolling Elements: Ball. Number Of Rows: 1. Bore Type: Straight. Closure Type: Open. Snap Ring Included: Snap ring fitted. Internal Clearance: CN. Bearing Material: Chrome steel. Series: 300K. Base Number: 311K. GTIN: 087796067141.

Decoding the designation

311 — the 300 heavy dimension series, bore code 11, which maps to the ISO 6311 envelope: 55 mm bore, 120 mm outside diameter, 29 mm width.

K — deep groove Conrad construction, which carries radial load and axial load from either direction and has no contact angle.

G — a snap ring groove machined in the outside diameter of the outer ring.

What these specs mean in practice

The snap ring seats in the outer ring groove and butts against the housing face, so the bearing is located axially without a separate shoulder or end cap. That shortens the housing and lets a through-bored housing hold position, which is the usual reason a designer calls for the NR execution. Internal Clearance: CN, the normal grade, with no clearance code on the designation. Precision Class: Not specified — the designation carries no tolerance suffix. Closure Type: Open, so the housing feeds oil or grease straight to the ball path.

Quantity and configuration

Unit Quantity: 1 Pc. One single-row bearing with its retaining ring fitted.

Interchange guidance

The envelope is the ISO 6311 NR envelope, 55 x 120 x 29 mm. SKF 6311 NR, FAG 6311-NR, NSK 6311NR, NTN 6311NR and Koyo 6311NR occupy the same seat with the same groove and ring. A plain 6311 has no groove and is a related size. Searchable variants include 311KG, 311 KG, 311-K-G, 6311-NR and 6311NR.