Time tested, proven, and made to ISO specification. Designed to handle a combination of radial and axial forces at a range of speeds, temperatures, and environments for an extended period with minimal friction.

Deep Groove, Single Row:

52100 alloy bearing steel, C3 internal clearance, steel cage, optional sealing and factory lubrication. Continuous use temperature range: -10°F to 248 °F.

Deep Groove, Single Row, High Temperature:

Heat stabilized 52100 alloy bearing steel, C4 internal clearance, steel cage, metal shields, HTB550 Grease. Maximum use temperature: 500°F, continuous use temperature range: -45°F to 400 °F.

Deep Groove, Single Row, Stainless Steel:

440C alloy bearing steel, C3 internal clearance, stainless steel cage, optional sealing and factory lubrication. Continuous use temperature range: -10°F to 248 °F.

Deep Groove, Double Row:

52100 alloy bearing steel, C3 internal clearance, polymer cage. Continuous use temperature range: -10°F to 248 °F.



Spherical Roller, Double Row, Cylindrical Bore:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, cylindrical bore, bronze cage. Continuous use temperature range: -10°F to 248 °F.

Spherical Roller, Double Row, Tapered Bore:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, tapered bore for mounting on withdrawal sleeve, bronze cage. Continuous use temperature range: -10°F to 248 °F.

Spherical Roller, Double Row, w/Adapter Sleeve:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, bronze cage, tapered bore with withdrawal sleeve, lock nut and clip included. Continuous use temperature range: -10°F to 248 °F.



Self-Aligning Ball, Double Row, Cylindrical Bore:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, cylindrical bore, steel cage. Continuous use temperature range: -10°F to 248 °F.

Self-Aligning Ball, Double Row, Tapered Bore:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, tapered bore for mounting on withdrawal sleeve, steel cage. Continuous use temperature range: -10°F to 248 °F.

Self-Aligning Ball, Double Row, w/Adapter Sleeve:

Self-aligning, 52100 alloy bearing steel, C3 internal clearance, steel cage, tapered bore with withdrawal sleeve, lock nut and clip included. Continuous use temperature range: -10°F to 248 °F.

Static Load Rating (Co [kN]): The basic static load rating C0 is defined in ISO 76 as the load that results in a certain value of contact stress at the center of contact of the most heavily loaded rolling element/raceway. The contact stress values are:

  • 4600 MPa for self-aligning ball bearings
  • 4200 MPa for all other ball bearings
  • 4000 MPa for all roller bearings

The stress values produce a total permanent deformation of the rolling element and raceway that is approximately: 0.0001 times the rolling element diameter. The loads are purely radial for radial bearings and axial for thrust bearings.

When any of the following conditions exist, bearing size should be selected based on the static load capacity:

  • The bearing is not rotating and is subjected to continuous high load or intermittent peak loads
  • The bearing makes slow oscillating movements under load
  • The bearing rotates and has to sustain temporary high peak loads
  • The bearing rotates under load at low speed < 10 RPM

Dynamic Load Rating (C [kN]): The bearing load that will result in an ISO 281 basic rating life of 1,000,000 revolutions

Fatigue load limit (Pu [kN]): Load level below which metal fatigue will not occur. For this to be valid, the lubricant film must fully separate the rolling elements from the raceways and rolling surfaces must be free from indentations, contaminants, or damage related to handling.

Equivalent dynamic bearing load (P [kN]): A calculated bearing load that is constant in magnitude and direction for bearings that experience forces that may not be constant or act both radially and axially. The resolved load acts radially on radial bearings and axially for thrust bearings.

Minimum Load ([kN]): Where there are very light loads, failure mechanisms other than fatigue, such as skidding and smearing of raceways or cage damage can occur. To provide satisfactory operation, rolling bearings must always be subjected to a given minimum load. In general these loads are:

  • 0.01C for all ball bearings
  • 0.02C for all roller bearings

Reference Speed (Nr [RPM]): The assessment of the speed capabilities from a thermal frame of reference, derived from thermal equilibrium under the ISO 15312 standardized operating and cooling conditions

The ISO reference speed is valid for open bearings only, operating under the following conditions:

  • Radial load P = 0.05Co for radial bearings
  • Axial load P = 0.02Co for thrust bearings
  • Temperature increase of 50°C (90°F) above an ambient reference temperature of 20°C (70°F)
  • Mineral oil lubrication without EP additives, ISO VG32 for radial bearings, ISO VG68 for thrust bearings
  • Clean conditions
  • Sufficient operating clearance
  • Horizontal shaft, rotating inner ring, and stationary outer ring

Limiting speed (Nmax [RPM]: The mechanical bearing limit that should not be exceeded unless the bearing design and the application are adapted for higher speeds. The limiting speed is determined by:

  • The form stability and strength of the cage
  • Lubrication of the cage guiding surfaces
  • Centrifugal forces acting on the rolling elements
  • Speed-limiting factors, such as seals and the lubricant for sealed bearings

Some open ball bearings have very low friction and the reference speeds listed for them might be higher than their limiting speeds. Do not use only the mechanical speed limit. The lower of the two sets the speed limit.

Bearing heat generation is the sum of the heat generated as a result of the combined bearing and seal frictional power loss and heat flow from adjacent parts or processes. The final temperature of the bearing will be based on the equilibrium of the ability to dissipate the generated heat.

Maximum Temperature: (Tmax [°C]): The maximum continuous use temperature for the bearing design

Minimum Temperature: (Tmin [°C]): The minimum continuous use temperature for the bearing design

Temperature limits for a given bearing type, size, and lubrication conditions are interdependent and can be enhanced or undermined by seal selection, lubrication, loading, speed. and bearing steel

Deep Groove Ball Bearings Don't Self-Align:

Standard deep groove ball bearings with a cylindrical outside diameter cannot self-align and must be accurately positioned to avoid stressing the components. There ability to compensate for misalignment is 0.2 degrees or less depending on internal clearance and the load direction. This can be made very close to 0 for precision applications by reducing clearance and axial pre-loading. This will maximize the accuracy of the machinery.

Self-Aligning Ball Bearings

Spherical Outer Race Profile:

Self-Aligning Ball Bearings and Spherical Roller Bearings have a spherical outer raceway that complements that allows the assembly to tilt several degrees during installation and operation dynamically. In general, Self-aligning ball bearings are more tolerant towards dynamic alignment at high speed than spherical rollers.
Cylindrical bore bearing Tapered bore bearing Tapered bore bearing on adapter sleeve

Cylindrical Bore

The bearing is either slip fit onto the shaft or into a housing and secured by an external method such as a setscrew or eccentric collar, or it is fit to a shaft or housing with mechanical interference for a secure hold.

Tapered Bore

A tapered shaft is mated with the a tapered bore bearing. The bearing is hydraulically or mechanically driven up the taper and secured with a large nut.

Adapter Sleeve Locking

A tapered sleeve is placed on the shaft and driven up hydraulically or mechanically into a tapered bearing bore, creating an interference fit. The sleeve is tightened and secured with a large nut. This design is ideal for preventing shaft fretting on high-speed equipment such as industrial fans and allows for easier installation on large bearings.


Adapter Sleeves

H series (ISO)

Basic adapter sleeve design that includes a tapered sleeve, nut and lock washer. Manufactured to ISO standard dimensions.

SNW series (ANSI)

Basic adapter sleeve design that includes a tapered sleeve, nut and lock washer. Manufactured to ANSI standard dimensions.

OH series (Hydraulic ISO)

Adapter sleeve design that includes porting for oil injection to aid in sleeve withdrawal. Commonly used on large bore bearings that require high force to install. Includes a tapered sleeve, nut and lock washer. Manufactured to ISO standard dimensions.

Bearings with a cylindrical bore

Bearings with a tapered bore

Deep Groove Ball Bearings
Self-Aligning Ball Bearings
E series Spherical Roller Bearings
K series Self-Aligning Ball Bearings
EK series Spherical Roller Bearings
bearing steel

Standard 52100 Alloy Bearing Steel:

Through hardened to RHC 60-63, precision ground, and polished to a low RMS for service to 248 °F

Stainless bearings, 440C Bearing Steel:

Standard corrosion resistant bearing steel, through hardened to RHC 60-63, precision ground, and polished to a low RMS for service to 248 °F. The chemical corrosion resistance of alloys varies greatly depending on the environment. New applications should be evaluated to determine the best solution to prevent corrosion.

High temperature bearings, Heat Stabilized 52100 Bearing Steel:

Hardened 52100 bearing steel is tempered at 500°F - 550°F to precipitate fine carbide and eliminate retained austenite created during quench hardening. This process produces bearing steel with low residual stress that will not be impacted by irreversible material volume changes caused by repeated exposure to hot and cold cycles or significant softening from further tempering. After treatment, the bearing is ground and polished to a low RMS and rated for continuous service from 400 °F to 500 °F depending on the exact process used.

Open Deep Groove Ball Bearing Sealed Deep Groove Ball Bearing -2RS Shielded Deep Groove Ball Bearing -ZZ

Open Ball Bearings (None)

Open bearings are commonly used when the bearing will be placed inside of an assembly or housing that contains its own sealing to protect internal hardware. Open bearings may also be preferred in some submerged applications.

Sealed Bearings (-2RS)

Elastomer contact seals are used to exclude fine dust, moisture and other penetrating contaminants from entering the bearing. Contact seals offer a high level of exclusion, but increase friction loss and may potentially limit thermal performance.

Shielded Bearings (-ZZ)

Close tolerance metal shields exclude large particulate and light industrial contamination without impacting performance but do not effectively stop fluids and gases from entering the bearing.

Grease is part of the seal:

All sealed ball bearings ship with standard factory lubrication unless specially requested otherwise. Grease plays a critical role in seal performance. Bearings must be adequately lubricated to wet the contact area between the bearing races to prevent ripping or wearing the and elastomer seal surface.

Internal ball bearing clearance

The ball or rollers running inside the bearing require clearance to rotate. Lower clearance increases the precision and load capacity, but increases operating temperature and the chance of thermal distortion causing binding. For most industrial applications, class C3 or C4 clearance will provide the best overall performance. High precision applications, such as machining center spindles and instrumentation, may require tighter tolerance from C0-C3.

C3 Clearance:

Most commonly used internal clearance class for applications up to 248 °F. Typically used with "standard" ball bearing construction

C4 Clearance:

For high temperature applications from 248 °F to 500°F or when a high interference fit is needed to secure the bearing.

C5 Clearance:

For very high temperature applications using specialty alloys over 500°F or when a high interference fit is needed to secure the bearing.

Products With C4 Clearance

  • Available on all bearings listed as high temperature
  • Any stock self-aligning ball bearing or spherical roller bearing can be ground to C4 on request

C0-C5 non-stock Clearance

For non-stock internal clearance from C0 to C5 contact HTB. Many units can be ground or made to order

Anti Corrosion and Wear Treatment:

Internal ball bearing clearance

Steel nitriding and sealing creates a hard ceramic case that self-lubricates and resists scuffing, micro-welding, corrosion, and particulate abrasion for all bearing surfaces. Provides a significant service life extension when poor lubrication, liquid corrosives, start/stop rotation, or high temperatures are present.

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