SKF 6311 55x120x29 mm - Deep Groove Ball Bearing

SKF 6311 55x120x29 mm - Single Row Deep Groove Ball Bearing

SKF 6311 is a single row deep groove ball bearing from the SKF 6300 series, with dimensions of 55x120x29 mm. The standard 6311 designation identifies an open bearing without integrated shields or seals, with normal radial internal clearance (CN). Its single row of balls and deep raceway grooves enable it to accommodate radial loads and axial loads in both directions. No additional suffix specifies special clearance, sealing or cage execution.

Technical Specifications - SKF 6311

The specifications refer to the standard open SKF 6311 bearing. They must not automatically be applied to versions with different suffixes, internal clearance, cage designs or sealing arrangements.

What Does SKF 6311 Mean?

The basic designation 6311 identifies the bearing type, dimensional series and bore diameter.

63 - Bearing dimensional series

The number 63 identifies the dimensional series of this deep groove ball bearing.

SKF 6311 belongs to the 6300 series, which includes single row deep groove ball bearings with standardized boundary dimensions.

11 - Bore diameter code

For this bearing designation, the bore code 11 corresponds to a nominal bore diameter of 55 mm.

The complete boundary dimensions are:

• Bore diameter: 55 mm

• Outside diameter: 120 mm

• Width: 29 mm

No additional suffix

The designation SKF 6311 does not include suffixes such as 2Z, 2RSH or C3.

This identifies the standard open execution with normal radial internal clearance, rather than a shielded, sealed or increased-clearance version.

Alternative Designations and Search References

Common written variations of the same bearing designation include:

• SKF 6311

• 6311 SKF

• SKF6311

• 6311 55x120x29 mm

The following designations identify different executions and must not be treated as alternative names for the standard SKF 6311:

• SKF 6311/C3

• SKF 6311-2Z

• SKF 6311-2Z/C3

Construction and Operating Principle

Single Row Deep Groove Ball Bearing Design

SKF 6311 consists of an inner ring, an outer ring, one row of balls and a cage that maintains the spacing between the rolling elements.

The deep raceway grooves provide radial load capacity and enable the bearing to accommodate axial loads acting in both directions.

However, the permissible axial load depends on the operating conditions and must not be assumed to equal the basic dynamic load rating.

Open Bearing Construction

The standard SKF 6311 is supplied without integrated shields or contact seals.

Its open construction allows lubricant to reach the rolling elements and raceways from the machine's lubrication system.

This design is relevant where the bearing arrangement provides its own lubrication and protection against contamination.

Unlike sealed bearings, the open SKF 6311 requires appropriate lubrication and environmental protection as part of the complete bearing arrangement.

Normal Radial Internal Clearance

SKF 6311 has normal radial internal clearance, designated CN.

Radial internal clearance is the total possible radial displacement of one bearing ring relative to the other before mounting.

The operating clearance is influenced by shaft and housing fits, thermal expansion and loading conditions.

The absence of the C3 suffix is technically significant. It should not be assumed that standard CN clearance and increased C3 clearance are interchangeable.

SKF 6311 Load Ratings and Operating Speeds

Basic Dynamic Load Rating C - 74.1 kN

The basic dynamic load rating is used when calculating rolling bearing fatigue life under dynamic loading.

It is not a universal maximum permissible operating load.

Actual bearing life depends on the equivalent dynamic bearing load, operating speed, lubrication conditions and contamination.

Basic Static Load Rating C0 - 45 kN

The basic static load rating is used to assess the risk of permanent deformation at the rolling element and raceway contacts.

It is relevant for stationary bearings, very slow rotation and applications involving high loads.

Reference Speed - 12,000 rpm

The SKF reference speed is a thermal reference value used in bearing speed calculations.

It is not an unconditional permissible continuous operating speed.

The reference speed depends on standardized assumptions regarding lubrication, loading and heat dissipation.

Limiting Speed - 8,000 rpm

SKF specifies a limiting speed of 8,000 rpm for the standard 6311 bearing.

The limiting speed reflects mechanical and other practical restrictions on bearing operation.

The actual permissible operating speed must be established from the complete bearing arrangement, lubrication method, loading and operating temperature.

The reference speed and limiting speed represent different technical concepts and must not be interpreted as interchangeable values.

SKF 6311 vs Other SKF 6311 Variants

These variants share the same basic boundary dimensions of 55x120x29 mm but differ in internal clearance or protective arrangements.

SKF 6311 vs SKF 6311/C3

Both versions have the same boundary dimensions and open construction.

The difference is radial internal clearance:

• SKF 6311: normal internal clearance, CN.

• SKF 6311/C3: increased internal clearance, C3.

C3 clearance may be required when bearing fits and operating temperatures are expected to reduce the internal clearance significantly.

However, increased clearance is not automatically preferable. The correct execution depends on the machine design and operating conditions.

SKF 6311 vs SKF 6311-2Z

SKF 6311 is an open bearing without integrated shields.

SKF 6311-2Z incorporates two metal shields designed to help retain lubricant and reduce the entry of contaminants.

Although the boundary dimensions are identical, the lubrication arrangement and protection against contamination differ.

Replacing an open bearing with a shielded version requires checking the requirements of the application.

Bearing Selection and Interchangeability

Before ordering SKF 6311, verify the following technical requirements:

• Exact manufacturer designation.

• Bore diameter of 55 mm.

• Outside diameter of 120 mm.

• Bearing width of 29 mm.

• Open bearing construction.

• Normal CN radial internal clearance.

• Required dynamic and static load ratings.

• Radial and axial operating loads.

• Rotational speed.

• Shaft and housing fits.

• Operating temperature.

• Lubrication method.

• Cage and tolerance requirements, where specified.

• Protection against contamination.

• Machine manufacturer's bearing specifications.

Identical dimensions do not guarantee complete technical interchangeability.

Bearings with different internal clearance, seals, shields, cages or tolerance classes may require different operating conditions.

Applications of SKF 6311

SKF 6311 can be considered for rotating shaft arrangements requiring a 55 mm bore, 120 mm outside diameter and 29 mm bearing width.

Its single row deep groove ball bearing construction makes it suitable for applications involving radial loads and axial loads in both directions, subject to bearing load calculations.

The open design is particularly relevant in machinery where lubrication and contamination protection are provided by the surrounding bearing arrangement.

Specific machinery models, OEM applications and equipment references should not be attributed to SKF 6311 without supporting manufacturer documentation.

Installation and Operating Recommendations

Cleanliness Before Installation

Inspect and clean the shaft, housing and mating surfaces before mounting.

Protect the raceways and rolling elements against contamination.

Correct Bearing Fits

Select the appropriate shaft and housing tolerances based on the loading conditions, operating temperature and required internal clearance.

Incorrect fits can affect operating clearance, bearing temperature and service life.

Applying Mounting Force

When mounting the bearing onto a shaft, apply mounting force to the inner ring.

When pressing the bearing into a housing, apply force to the outer ring.

Never transmit mounting force through the balls and raceways.

Lubrication

The standard open SKF 6311 does not have a factory grease filling intended for service operation.

The bearing arrangement must provide suitable grease or oil lubrication.

Lubricant selection and quantity depend on rotational speed, load, operating temperature and the machine's lubrication system.

Storage

Store the bearing in its original packaging in a clean, dry environment.

Protect it against moisture, corrosion and mechanical damage.

Frequently Asked Questions - SKF 6311

What are the dimensions of SKF 6311?

SKF 6311 has a bore diameter of 55 mm, an outside diameter of 120 mm and a width of 29 mm. Its dimensions are 55x120x29 mm.

Is SKF 6311 an open bearing?

Yes. The standard SKF 6311 is an open deep groove ball bearing without integrated shields or seals.

What is the dynamic load rating of SKF 6311?

The basic dynamic load rating is 74.1 kN, while the basic static load rating is 45 kN.

What is the difference between SKF 6311 and SKF 6311/C3?

SKF 6311 has normal CN radial internal clearance. SKF 6311/C3 has increased C3 clearance. Both versions share the same basic dimensions.

What is the limiting speed of SKF 6311?

The catalogue limiting speed is 8,000 rpm. SKF also specifies a reference speed of 12,000 rpm. These values describe different speed-related criteria.

Is SKF 6311 factory lubricated?

The standard open SKF 6311 is not supplied with a factory grease filling intended for operation. Suitable lubrication must be provided by the machine's bearing arrangement.

Can SKF 6311 be replaced with SKF 6311-2Z?

Not automatically. SKF 6311 is open, while SKF 6311-2Z has two metal shields. The lubrication method and contamination protection requirements must be checked before substitution.

Can another manufacturer's 6311 bearing replace SKF 6311?

Only after verifying the complete technical specification, including dimensions, internal clearance, cage execution, tolerance class, load ratings and operating requirements. Matching boundary dimensions alone do not establish full interchangeability.

SKF 6311 - Key Technical Information

SKF 6311 is a single row deep groove ball bearing from the 6300 series, measuring 55x120x29 mm. The standard execution is open, without integrated seals or shields, and has normal CN radial internal clearance. Its basic dynamic load rating is 74.1 kN, static load rating 45 kN and limiting speed 8,000 rpm. External lubrication is required.

SKF 6311 at simmering.pl

SKF 6311 is offered through simmering.pl, a specialist supplier of rolling bearings and industrial mechanical components.

We support maintenance departments, machinery repair specialists, engineers and industrial B2B procurement customers.

Our warehouse and order processing operations are located in Lublin, Poland. We supply customers throughout Europe and offer worldwide shipping.