BEARINGDEX
Angular contact ball

7311 bearing

55 mm bore, 120 mm outside diameter, 29 mm width (2.1654 × 4.7244 × 1.1417 in).

Dimensions

mminch
Bore d552.1654
Outside diameter D1204.7244
Width B291.1417

Quick numbers

Pitch diameter dm87.5 mm
Section height (D − d)/232.5 mm
n·dm at 1,800 rpm157,500
n·dm at 3,600 rpm315,000

Compare against the maker's limiting speed. Speed calculator · L10 life

What the number means

7Angular contact ball
3Diameter series 3: medium. Width series 0 is implied and left off.
11Bore code 11 × 5 = 55 mm

Same size, different bearing

These share the 55 × 120 × 29 mm envelope but carry load differently. They aren't drop-in swaps.