7304-BECBY bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 7304-BECBY model number is decoded

7304 BECBY is SKF's 20 mm-bore single-row angular-contact ball bearing in the 7300 series, nominal 40° (B) contact angle, 20×52×15 mm to the ISO dimension plan. 40° contact angle (suffix B): the steep standard single-row angle, giving the highest axial capacity at the cost of speed, with a recommended load ratio Fa/Fr ≥ 1. E marks the optimized internal design with an enhanced ball complement and race geometry. stamped brass cage, ball-centred (suffix Y) — lighter than the machined M cage but brass rather than polymer. CB means universally matchable with Normal axial internal clearance: the two side faces are ground so any two units form DB (back-to-back), DF (face-to-face) or DT (tandem) sets without regrinding. BECBY combines the optimized 40° geometry with CB universal clearance and a stamped brass Y cage. Envelope 20×52×15 mm (0.787×2.047×0.591 in), 16.0 mm radial section height, C 20.4 kN, C0 11.2 kN, Pu 0.475 kN.reference speed 17,000 r/min (thermal) and limiting speed 18,000 r/min (mechanical), catalogue mass 140 g. Speed planning distinguishes the two published ceilings mechanically: the cage and balls tolerate 18,000 r/min while thermal balance under catalogue load sets the 17,000 r/min reference; at dm ≈ 36.0 mm the corresponding dn is approximately 648k mm·r/min. Sizing arithmetic on the 20 mm bore: 20.4 kN C divided by the 16.0 mm radial section height gives 1.3 kN per section millimetre; the 140 g mass and 2 % Pu/C share frame the light-load floor for the adjusted-life check. Bore-to-OD planning: OD 52 over bore 20 is a 2.60× step for this size, and the 15 mm width gives a bore/width ratio of 1.33; use these ratios when housing space around the 20 mm shaft is the first constraint. Cage detail specific to this order number: the Y cage is stamped from brass strip into ball pockets rather than machined from solid, giving a lighter cage assembly and lower centrifugal mass than the M execution; it remains brass (temperature and oil-additive tolerant, unlike PA66) but is the formed-cage design, and the machined-brass BECBM order number remains the choice for severe shock or marginal lubrication.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Do not mix execution classes inside one set: a universally matchable BECBY unit is ground for arbitrary pairing, a basic execution is not.
• DB pairs give the highest moment stiffness, DF pairs tolerate misalignment and thermal expansion better, DT shares heavy one-direction thrust; choose from the shaft thermal calculation rather than by habit.
• At 20 mm bore the k5 seat assumes a steel shaft and housing; aluminium housings grow faster with temperature, so re-check the outer-ring setting when the case is non-ferrous.
• Reference and limiting speeds are different ceilings: design to both, and remember preload and oil/air cooling move the real thermal limit far from the catalogue reference value.
• The steep 40° angle of 7304-BECBY favours thrust-heavy combined loads; for a predominantly radial high-speed position the 25° ACCBM execution of the same size is the alternative order number.
• Universally matchable BECBY bearings arrive ready for set mounting, not preloaded sets: preload results from how the set is clamped, so follow the SKF stand-off-ring and nut-torque procedure.