The 31313 is a 65 × 140 × 36 mm, single-row tapered roller bearing designed for high combined radial and axial loading [S1].
Its 13-series geometry places it among steep-angle tapered roller bearings, making the designation relevant to industrial shafts that must carry substantial thrust without accepting deep-groove ball bearing limitations [S1][S3].
31313 Dimensions, Series, and Load Role
The 31313 boundary dimensions are 65 mm bore, 140 mm outside diameter and 36 mm overall width, identifying it as a metric 313-series tapered roller bearing [S1]. The 313 designation denotes a steep contact angle within the 300 series, while the final 13 identifies the size code within that dimensional family [S1][S3].
This bearing is a single-row tapered roller design, and its roller geometry and raceway profile are intended to support significant radial force together with axial thrust [S1]. Anti-friction bearings are used across broad speed ranges and many combinations of radial and thrust loads, but the selection must still be calculated from the actual load direction, speed and required life [S3].
The 31313 is suitable for applications where axial load is a substantial part of the duty, not merely an incidental radial-load reaction. Its steep angle improves thrust handling compared with shallow-contact bearings, while tapered rollers provide the load path and contact geometry needed for combined loading [S1][S3].
Selection Criteria: Axial Capacity, Speed, and Life
A 31313 selection should begin with a quantified load combination rather than a bore-size match. The calculated dynamic equivalent load must be compared with the manufacturer’s rating for the exact internal design, speed, reliability and lubrication condition, while the static equivalent load must also be checked against shock or standstill loading [S3][S4].
Speed is a separate acceptance criterion. A 65 mm bore does not establish whether the selected internal clearance, cage, precision class and lubrication can sustain the operating speed, and the speed rating must be checked against the actual duty rather than inferred from the 31313 code [S3][S4].
Clearance changes the operating geometry. An NSK technical report records an angular-contact bearing whose initial 15° contact angle changed to 26° under axial load, illustrating why nominal catalogue angle alone is not a substitute for a loaded-clearance calculation [S4]. The same technical framework covers dynamic load rating, static load rating, fitting, internal clearance and residual clearance after mounting [S4].
Temperature is equally important because lubricant viscosity and fit interference affect bearing life. The Timken engineering manual treats operating temperature, heat generation, dissipation, lubrication and seals as dedicated engineering topics, while NSK includes interference changes caused by temperature differences between inner and outer rings in its fitting calculations [S3][S4].
31313 Versus Angular Contact and Deep Groove Options
The 31313, a 313R angular contact ball bearing and a 313-Z deep groove ball bearing share the 65 mm bore, but their load paths and operating roles differ. The 31313 is a tapered roller bearing for heavy combined radial and axial load; the 313R is a single-row open angular contact ball bearing rated for heavy radial load and directional thrust; the 313-Z is a deep groove ball bearing with higher radial capacity than an unfilled equivalent but only limited axial capacity in both directions [S1][S5][S9].
Angular contact bearings can sustain radial, axial or composite loads, but a single-row unit’s axial load must act in one direction [S7]. Paired or stacked arrangements are therefore often considered when opposing thrust or greater axial stiffness is required, whereas the deep groove 313-Z is not the first choice when axial thrust dominates [S7][S9]. The exact 313R dimensions in the cited listing are 65 mm ID, 140 mm OD and 33 mm width, with an open cage and no snap ring [S5].
Application Fit and Failure Modes
A 31313 fits shaft arrangements with large axial thrust, including heavily loaded conveyor drive stations, industrial gearboxes, rolling equipment and machine-tool structures where a tapered roller bearing is justified. It is less suitable where the shaft must carry only light axial force, where very high speed makes its load rating and thermal balance unsuitable, or where continuous reversal of thrust rules out a single-direction arrangement [S1][S3][S7].
Misalignment, inadequate lubrication, contamination and incorrect mounting can defeat an otherwise adequate bearing. The NSK report includes separate sections on inner and outer ring misalignment, oil shortage, shearing heat generation, mounting and withdrawal loads, and tolerances for bore and outside diameter [S4]. The Timken manual likewise covers bearing reactions, fitting practice, setting, speed ratings, lubrication and seals [S3].
Single-direction thrust is a fundamental installation constraint for the 31313, and a complete arrangement may require a second bearing to react the opposing force. The need for two bearings, a defined housing, a controlled fit and a setting method must be established before the catalogue size is accepted [S3][S7].
Installation, Setting, and Sourcing Controls
Installation control starts with the 65 mm bore, 140 mm outside diameter and 36 mm width, followed by calculation of ring fits, clamping forces, surface pressure and mounting stresses. NSK’s technical material covers required effective interference, interference deviation caused by temperature rise, fit calculation, surface pressure and maximum fitting-surface stress [S4].
The mounting sequence must prevent damage to the tapered raceways and rollers, and the selected method must control the internal setting rather than rely on arbitrary axial tightening. Timken’s tapered roller bearing installation material is part of a 220-page engineering manual whose index also covers tolerance systems, speed ratings and bearing-life calculation [S3].
Procurement should lock the 65 × 140 × 36 mm envelope, the 31313 designation, the required contact angle, clearance class, precision, cage, seal or shield arrangement, lubrication and mounting orientation. The cited 31313 listing establishes the size and high-capacity role, while the engineering manuals provide the calculation framework for load, life, clearance, fit and installation [S1][S3][S4].
Choosing Between 31313 and Three-Row Slewing Bearings
The ISB ER3 standard series uses three rows of crossed roller bearings, with two rows accommodating axial loads and one row accommodating radial load [S2]. That architecture is materially different from a single-row 31313: the ER3 arrangement is suited to large-diameter slewing and heavy radial plus axial loads, whereas the 31313 uses a conventional tapered roller contact line to support a 65 mm bore shaft.
Selection should compare load capacity, envelope, speed, installation and load direction. A 65 × 140 × 36 mm 31313 is a compact shaft-bearing choice with a 36 mm width, while an ER3 crossed-roller slewing bearing separates radial and axial load paths across three rows and requires a substantially different housing and mounting arrangement [S1][S2].
For a 31313, the decisive checks are combined-load rating, static capacity, speed, clearance and setting. For ER3, the decisive checks are slew-ring geometry, radial and axial load paths, structural integration and the operating conditions of the slewing mechanism. Neither should be substituted merely because both carry axial force [S2][S3][S4].
Engineers should obtain the manufacturer’s current catalogue for the exact 31313 internal design, then compare its load ratings, limiting speed, clearance, fits and installation requirements against the actual shaft loads. The next trackable procurement checks are the final 31313 manufacturer datasheet, the applied radial and axial load spectrum, and the mounting drawing showing bearing orientation and setting method.