SKF 81xxx Cylindrical Roller Thrust Bearing — Dimensions, Load Ratings & Interchange (81102 to 81140)

SKF 81xxx cylindrical roller thrust bearing reference: bore d, outside diameter D, height H, dynamic (C) and static (C0) load ratings, and limiting speed for the 81100 (light) and 81200 (medium) TN series from 81102 (bore 15 mm) through 81140 (bore 200 mm). Includes SKF K-suffix variants (K81xxx with a separate housing washer), interchange to FAG, NSK, NTN and Timken cylindrical roller thrust bearings, cage-material notes (TN nylon vs TVPB), fatigue-load limit Pu values, and application guidance for gearbox reaction, marine thrust and hydraulic press service.

SKF 81xxx cylindrical roller thrust bearing (81100 & 81200 series)

The SKF 81xxx cylindrical roller thrust bearing is a single-direction axial-load bearing built from three separable parts: a shaft washer, a housing washer and a caged assembly of straight cylindrical rollers. It is the standard choice for reacting one-way axial loads where a full-complement needle thrust cage is too load-limited, and where a spherical roller thrust bearing's misalignment tolerance is not required. Typical service includes gearbox reaction, worm-gear output shafts, marine propeller thrust, vertical pump columns and mechanical-press ram guides — anywhere the load direction never reverses and the shaft-and-housing rigidity keeps misalignment under 0.001 rad.

SKF sells the range in two size families: the 81100 TN series (light section, bore 15-200 mm) and the 81200 TN series (medium section, higher load rating for the same bore, bore 15-140 mm). The TN suffix denotes a polyamide-6.6 cage stabilised for continuous service to 120 °C; the older TVPB suffix denotes a glass-fibre-reinforced polyamide cage rated to 180 °C for higher-temperature service. A K prefix (K81xxx) indicates the bearing is supplied with a separate spherical seat housing washer that self-aligns up to ±3° — useful where the housing bore cannot be machined perfectly perpendicular to the shaft. The table below gives the SKF General Catalogue dimensional and load-rating data for the 81100 series across the bore range that covers 95 % of specifying applications.

81100 series dimensions and load ratings

Dimensions to ISO 104:2015. Load ratings are calculated to ISO 76:2006 (static) and ISO 281:2007 (dynamic) using the ISO life-modification factor a_ISO. Limiting speed is the reference speed for grease lubrication; oil lubrication supports approximately 1.4 × the grease speed at the same operating temperature. The fatigue load limit Pu is the axial load below which infinite ISO 281 life is expected under otherwise ideal conditions.

81200 series (medium section)

The 81200 series shares the same bore range as 81100 but with a thicker cross-section and correspondingly higher load ratings. Use 81200 when the axial-load duty exceeds 81100 by ≥ 20 % or when the ambient shock loading calls for a higher static safety factor.

K-suffix (K81xxx) self-aligning variant

The K81xxx variant adds a separate housing washer with a spherical seat, machined to match a spherical seating ring supplied with the bearing or, on larger sizes, machined into the housing itself. Self-alignment capability is typically ±0.5° to ±3° depending on size and setup. Use K81xxx when:

• Machining tolerances between shaft and housing cannot guarantee perpendicularity to under 0.001 rad (0.06°).
• Thermal expansion of the housing will tilt the housing washer relative to the shaft washer during operation (typical on hot pumps and gearbox output shafts).
• Shaft deflection under load will misalign the two washers — common on cantilevered marine thrust shafts and vertical pump columns.

The K81xxx bore, OD and load rating are identical to the base 81xxx. Only the height H and mass increase, by the height of the spherical seat washer (typically 4-8 mm depending on size).

Interchange to other bearing makers

Cylindrical roller thrust bearings in the 81100 and 81200 series are dimensionally interchangeable between all major bearing makers because ISO 104 fixes the boundary dimensions (d, D, H). The load-rating C values vary slightly (typically ±10 %) because each maker's rolling-contact fatigue calculation applies a proprietary a_ISO factor. The material and cage may also differ (SKF TN = polyamide 6.6; FAG PB = polyamide 4.6; NSK M = brass; NTN T2 = steel). For a direct replacement, match the SKF designation to the equivalent below:

Timken uses the "T" prefix for its cylindrical roller thrust range (T102 = 81102), and the last two or three digits match the bore-in-mm / 5 rule — T140 has a 100 mm bore, T220 has a 190 mm bore. Verify the Timken bore against the SKF equivalent before ordering.

Selecting the bearing — axial-load sizing

Cylindrical roller thrust bearings are sized by the equivalent dynamic axial load P and the required L_10h rating life in operating hours. Use the standard ISO 281 relation:

L_10h = (10⁶ / 60n) · (C / P)^10/3, where L_10h is the 90 %-survivor life in hours, n is the operating speed in rpm, C is the dynamic load rating (kN, above), and P is the equivalent dynamic axial load (kN).

Target life is typically 20,000 h for continuous industrial machines, 30,000 h for pumps and fans, and 40,000-100,000 h for stationary gearboxes. Marine main thrust bearings and mechanical presses are typically sized for 100,000+ h. Where the axial load varies over the operating cycle, use the cube-root mean of the load segments weighted by their operating time fraction.

Lubrication and mounting notes

• Grease — standard lithium-complex grease (NLGI 2) is adequate to the limiting-speed values in the table. Above 70 % of limiting speed, switch to a synthetic grease (PAO or ester base) to control operating temperature.
• Oil — for continuous-service applications, an ISO VG 68 mineral oil at 40 °C or an ISO VG 100 for higher temperatures. Oil-mist and oil-jet supply extend service life at speeds > 1.4 × the grease-limiting speed.
• Mounting — the shaft washer is the smaller-bore half; the housing washer has the larger OD. Confirm before pressing to avoid a reversed installation, which will destroy the bearing in seconds.
• Housing seat — the housing bore must be perpendicular to the shaft axis to under 0.001 rad. If in doubt, specify a K81xxx (self-aligning) variant.
• Preload — unlike angular-contact ball bearings, cylindrical roller thrust bearings do not need preload. Assemble with a light axial residual load (~0.005 × C static) to prevent skidding at start-up, then let the operating axial load dominate.

Related products and references

• SKF 81102TN cylindrical roller thrust bearing on cBallast
• SKF K81102TN self-aligning variant
• All SKF 81xxx cylindrical roller thrust bearings on cBallast
• Cylindrical roller thrust bearings across brands
• SKF bearings, seals and lubrication
• Bearings category

Dimensions and load ratings are the SKF General Catalogue values for the TN cage variant. Confirm against the current SKF product data sheet and the specific application's operating conditions (temperature, contamination, misalignment, load spectrum) before selection.

Reference compiled for identification and cross-reference. Dimensions are nominal; confirm against the controlling SKF SKF General Catalogue 6000/I EN (metric series) revision and the specific component data sheets before manufacture or procurement. All trademarks are the property of their respective owners.