21315 bearing: complete specifications & equivalents

Specification table

Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24

Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for 21315 are being backfilled — use the inquiry form for certified values.

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 21315 model number is decoded

In the 21300-series (ISO 15 dimension series) the leading 2 marks a double-row spherical roller and the last two digits of 21315 encode the bore: code 15 = 75 mm (code × 5 from 04 upward). The ISO 15 envelope is 160 mm outside diameter and 37 mm width — 2.953 × 6.299 × 1.457 in, with a 42.5 mm radial section height. Two rows of symmetrical barrel rollers on a common sphered outer raceway self-align to shaft deflection while carrying heavy radial load and bidirectional axial load. Typical catalogue practice for a rotating inner ring is a k5 shaft seat, H7 housing and C3 internal clearance; K variants use a 1:12 tapered bore on an adapter sleeve — verify against the mounting arrangement.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• On this 75 mm-bore 21315, specify C3 clearance as the default for an interference inner-ring fit and verify residual play after mounting; a medium-section row that ran free on the bench can be fully clamped at operating temperature on the 75 mm shaft.
• The 213 series at 75 mm bore keeps the 37 mm width comparatively narrow for its 160 mm OD; it fits restricted axial space but carries less load than a 22315, so substitution into heavy 223 duty — even at identical bore and OD — will shorten life.
• The 37 mm-wide 21315 seats against shaft and housing shoulders whose fillet must clear the bearing chamfer: keep the corner radius small enough that the 75 mm bore and 160 mm OD faces abut square — an undercut beats an oversized radius, which lifts the ring and edge-loads the 42.5 mm section.
• For a cylindrical-bore 21315, warm the inner ring to 80–100 °C (induction heater, never a flame) and slide it dry to the shoulder of the 75 mm shaft; cooling creates the interference, while hammering cold through the 160 mm assembly dents the sphered raceways.
• When reusing a sleeve-mounted 21315, inspect the adapter and lock parts together with the bearing: a stretched sleeve or a bent lockwasher tab that let the inner ring creep on the 75 mm journal must be replaced, or the new bearing frets the same seat.
• Spherical rollers need a minimum radial load to keep the rollers driven — as a rule of thumb about 2% of the basic dynamic load rating; an unloaded 21315 on an idler or in a cold-start drive will skid and smear, so add preload, reduce the bearing size or use a sealed grease-filled variant.
• Choose the bore type deliberately: plain 21315 takes a cylindrical seat, while the K variant has a 1:12 tapered bore and mounts on an adapter sleeve (H3xx series) over a plain commercial shaft or directly on a tapered journal — the two mounting procedures are not interchangeable.