53318 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 53318 model number is decoded

Listed in SKF 17000 chapter 5, 53318 is an ISO 104 single-direction thrust ball bearing, 90 mm bore and 155 mm OD, with a sphered housing washer and U seat washer, standing 54.6 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 18: bore 90 mm (code 18 × 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 90×155×54.6 mm (3.543×6.102×2.15 in), 32.5 mm radial section, C 182 kN, C0 440 kN, Pu 14.6 kN. Mounted height H1 59 mm includes the U 318 seat washer; the bearing alone is 54.6 mm high. reference speed 1,400 r/min (thermal) and limiting speed 2,000 r/min (mechanical), catalogue mass 4700 g. Capacity density: 182 kN C from 4.700 kg of bearing steel gives about 38.7 kN per kilogram; static density is correspondingly 93.6 kN/kg at C0 440 kN. At the printed limiting speed of 2,000 r/min the mean pitch diameter dm ≈ 122.5 mm implies a dn value around 245k mm·r/min; the 1,400 r/min reference speed is the thermal-planning value under catalogue load. Sizing arithmetic on the 90 mm bore: 182 kN C over the 32.5 mm radial section gives 5.6 kN per section millimetre, and the 54.6 mm stack height is 1.68× that section — proportions typical of a 53300 thrust section. Pitch-diameter arithmetic: dm = (90+155)/2 = 122.5 mm; at the 2,000 r/min limiting speed that corresponds to roughly 245k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. Washer-annulus check: the π/4·(D²−d²) contact annulus of 53318 covers about 12,507 mm², distributing C0 440 kN over a mean track circle of π·dm ≈ 385 mm. 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 155 mm washer can tilt inside the U 318 seat; check the actual tilt allowance in the mounting drawing, since the 4.4 mm washer thickness step does not by itself quantify it.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• 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.
• Replacement orders must list both 53318 and U 318: the seat washer is a separate article, and a U washer of the wrong size narrows the contact band of the 440 kN static-rated set.
• Dimension the housing to the 59 mm mounted height H1 (bearing plus U 318), not the 54.6 mm bearing height H — confusing the two is a recurring drawing error for the 53-series.
• Minimum axial load still applies with factor A 1.3: a self-aligning seat does not prevent ball skidding, so provide spring preload or sufficient rotor weight at light load and speed.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 53318 as the single sphered pressed steel execution; other order numbers of the 53318 size are different products and may carry different ratings or seating geometry — always quote the full designation including the U 318 seat washer when purchasing.