53309 bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-28

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 53309 model number is decoded

Listed in SKF 17000 chapter 5, 53309 is an ISO 104 single-direction thrust ball bearing, 45 mm bore and 85 mm OD, with a sphered housing washer and U seat washer, standing 30.1 mm high before installation. The bearing is delivered as separate, interchangeable parts: a ground-bore shaft washer, a loose-bore housing washer and the ball-cage assembly between them, designed for one axial load direction only. 53xxx reads as 5 (thrust ball), 3 (single direction with a sphered housing washer), a 2–4 section digit and the bore code; the U seat washer companion carries the matching three-digit number. reading the ending 09: bore 45 mm (code 09 × 5) for this single-direction size, via the standard exceptions 00/01/02/03 and ×5 above them. no cage suffix means the standard stamped steel retainer — a pressed sheet-metal ball-cage assembly that covers the bulk of the thrust-ball assortment. Envelope 45×85×30.1 mm (1.772×3.346×1.185 in), 20.0 mm radial section, C 76.1 kN, C0 153 kN, Pu 5.6 kN. Mounted height H1 33 mm includes the U 309 seat washer; the bearing alone is 30.1 mm high. reference speed 2,600 r/min (thermal) and limiting speed 3,800 r/min (mechanical), catalogue mass 830 g. Light-load floor: Pu = 5.6 kN is the equivalent-load threshold below which the SKF adjusted-life equation credits very long life for 53309; the number is 7 % of the 76.1 kN dynamic rating. Bore-to-OD planning: OD 85 over bore 45 is a 1.89× step for this size, and the 30.1 mm height gives a bore/height ratio of 1.50; use these ratios when the housing recess around the 45 mm shaft is the first constraint. Pitch-diameter arithmetic: dm = (45+85)/2 = 65.0 mm; at the 3,800 r/min limiting speed that corresponds to roughly 247k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Sizing arithmetic on the 45 mm bore: 76.1 kN C over the 20.0 mm radial section gives 3.8 kN per section millimetre, and the 30.1 mm stack height is 1.51× that section — proportions typical of a 53300 thrust section. Speed-ratio note for this exact unit: the reference speed is 2,600 r/min against a 3,800 r/min limiting speed, a reference-to-limit ratio of 0.68. Sphered-seating order-number note: the convex back face of the housing washer is finish-ground spherical and is delivered to mate with the separately ordered U seat washer, which presents a flat face to the housing and a concave face to the washer; together they accommodate initial static misalignment, but the pair must be kept clean, greased at the spherical interface and never replaced by a washer-on-flat-steel makeshift. The aligning angle is set by how far the sphered back of the 85 mm washer can tilt inside the U 309 seat; check the actual tilt allowance in the mounting drawing, since the 2.9 mm washer thickness step does not by itself quantify it.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Keep the sphered interface clean and lightly greased: scale, paint or grit between the washer back and U 309 locks the aligning function and frets under load; re-grease the contact at every overhaul.
• The spherical seat accommodates INITIAL static misalignment between shaft and housing; it is not a swivel for continuous oscillation, and the bearing still carries pure axial load with no radial capacity.
• The self-aligning feature is checked at commissioning by hand: with the shaft under no load the assembly must swivel and settle; a stiff spherical seat means dirt, a mismatched U washer, or a register bored off-axis.
• Minimum axial load still applies with factor A 0.12: a self-aligning seat does not prevent ball skidding, so provide spring preload or sufficient rotor weight at light load and speed.
• The 76.1/153 kN figures belong to 53309 specifically (the single sphered pressed steel execution of 53309); suffixed, sphered and counterpart-series order numbers are separate articles, and U 309 is ordered separately, so write the complete designation on the order and the maintenance record.