A4059-A4138 bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB) · extracted 2026-09-28

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB); 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 A4059-A4138 model number is decoded

Cone-and-cup identity in A4059: the leading A 4059 reference identifies the inner ring, rollers and cage; the trailing A 4138 reference identifies the outer ring. The A4000-series series lists alternative cups for the same cone, each producing a different 34.988 mm OD or 10.998 mm width — hence a different SKU even though the bore stays at 15 mm.Ordering number SKF A 4059/A 4138 in SKF catalogue PUB BU/P1 17000 denotes a single-row tapered roller bearing for a 15 mm shaft, inch series, with an open pressed-steel-cage execution and one-direction axial capacity.The A4000-series series assigns 15 mm bore, 34.988 mm OD and 10.998 mm width to A4059; the cone and cup references are not interchangeable with other inch-series pairs even when the bore matches, because the cup profile and rib geometry are series-specific. In SKF suffix language a bare A4059 is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. Speed planning uses two different ceilings: 17,000 r/min thermal reference and 22,000 r/min mechanical limiting speed. Specify pairs rather than single units wherever thrust reverses: the tapered contact of A4059 generates an induced axial load under radial force, and an unpaired bearing on a reversing shaft will run slack and fret its seat. Load system: the 16.5 kN basic dynamic rating C and 13.2 kN static rating C0 give a C0/C balance of 0.80, and dividing C by the 15 mm bore yields 1.10 kN per millimetre of journal — a density metric that compares across families; the 1.29 kN fatigue limit Pu is the floor beneath which the adjusted-life calculation drops below acceptable L10 hours for a 15 mm shaft carrying variable duty.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At a 15 mm bore the thin cone and cup are easily distorted by an over-tight shaft nut; check seat runout (target Ra ≤ 0.8 µm) and torque the locknut progressively — a pinched A4059 shows up as gearbox vibration long before it fails.
• The A4000-series inch series at 15 mm bore (34.988×10.998 mm) follows the Timken cone/cup convention; substitutions must match both the cone and cup reference exactly — interchanging with another series or a metric 3xxxx bearing of the same bore changes OD, width and contact angle, so re-run the pair setting and shoulder-diameter checks before swapping.
• O (back-to-back) pairs are stiffer against moments, X (face-to-face) pairs tolerate misalignment and thermal growth better; choosing the arrangement from the 2D drawing rather than the actual shaft thermal expansion is a common A4059 mounting error.
• Do not mix brands or executions inside one A4059 pair — matched sets are ground for a specific setting, and pairing a SKF basic unit with a different suffix variant will not share the setting evenly.
• Open A4059 units need application-supplied sealing and a defined EP lubricant supply; the roller-rib contact is the first to fail when the additive film breaks down.
• The 16.5/13.2 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
• SKF lists several executions of A4059 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF A 4059/A 4138 designation when purchasing and match the execution to the mounting arrangement.