53306 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 53306 model number is decoded

53306 is SKF's 30 mm-bore single-direction thrust ball bearing in the 53300 series to the ISO 104 dimension plan, with a sphered housing washer paired to a U seat washer, measuring 30×60×22.6 mm U 306 seat washer companion included in the mounted H1 dimension. The separable set comprises a shaft washer (ground bore, tight fit on the shaft), a loose-bore housing washer and one ball-cage assembly, reacting axial force in one direction and carrying no radial load. in the 53xxx designation the 3 marks a single-direction bearing whose housing washer has a sphered (convex) seating surface, intended to run against the matching U seat washer; the third digit 2–4 grades the section. the final two digits 06 encode the bore as 30 mm (code 06 × 5), the standard SKF bore-code rule shared with radial bearings. with no cage suffix this is the standard execution with a stamped sheet-steel ball-cage assembly (pressed cage) — the light, quiet and economical cage for small and medium thrust-ball sizes. Envelope 30×60×22.6 mm (1.181×2.362×0.89 in), 15.0 mm radial section, C 35.8 kN, C0 65.5 kN, Pu 2.4 kN. Mounted height H1 25 mm includes the U 306 seat washer; the bearing alone is 22.6 mm high. reference speed 3,800 r/min (thermal) and limiting speed 5,300 r/min (mechanical), catalogue mass 330 g. Speed band width for this size is 1,500 r/min between reference and limiting (1.39× ratio); lubrication, preload and heat removal decide where inside that band 53306 can actually run. Mass and section check: 330 g inside the 30×60×22.6 mm outline leaves a 15.0 mm radial section, and the 65.5 kN static rating is 1.83× the dynamic rating — plan static safety and minimum preload against those figures. Speed planning separates the two ceilings mechanically: the pressed cage and balls tolerate 5,300 r/min while thermal balance under catalogue load sets the 3,800 r/min reference; at dm ≈ 45.0 mm the corresponding dn is approximately 239k mm·r/min. Stack/annulus proportions: the 22.6 mm axial stack over the 2,121 mm² washer annulus gives 10.66 mm of height per annular square millimetre ×10⁻³, and at 330 g the bearing holds about 198.5 kN of C0 per kilogram. Pitch-diameter arithmetic: dm = (30+60)/2 = 45.0 mm; at the 5,300 r/min limiting speed that corresponds to roughly 239k mm·r/min, the figure used when comparing cage speed demand across the thrust-ball series. 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. Procurement reminder for this specific page: 53306 and U 306 are two order numbers shipping as two articles; the installed 25 mm H1 rather than 22.6 mm H is the dimension the housing drawing must carry.

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 53306 and U 306: the seat washer is a separate article, and a U washer of the wrong size narrows the contact band of the 65.5 kN static-rated set.
• Minimum axial load still applies with factor A 0.026: a self-aligning seat does not prevent ball skidding, so provide spring preload or sufficient rotor weight at light load and speed.
• The shaft washer remains the tight, ground-bore component on the 30 mm shaft; the sphered part is the HOUSING washer, and the U seat washer is the loose flat-backed part — the fitting order is shaft washer and cage set first, then housing washer and U 306 into the register.
• Ordering discipline for 53306: the catalogue page quotes 53306 plus U 306 and its 35.8/65.5 kN ratings as one exact article; bare-number substitutions from another series or brand need a fresh dimension and rating check, not a like-for-like assumption.