RNA 4903 JNS 22x30x13 mm

RNA 4903 JNS 22x30x13 mm - Needle Roller Bearing Without Inner Ring

RNA 4903 JNS 22x30x13 mm is a radial needle roller bearing manufactured by JNS (Nose Seiko, Japan), belonging to the RNA 49 dimensional series. The bearing features a machined outer ring and needle rollers but does not include an inner ring. Its rolling elements operate directly on a suitably hardened and ground shaft raceway. The nominal dimensions are 22 mm roller set bore diameter (Fw), 30 mm outside diameter (D), and 13 mm bearing width (C). This construction is designed primarily to accommodate radial loads in compact mechanical assemblies.

Technical Specifications - RNA 4903 JNS

Important: The 22 mm dimension refers to the roller set bore diameter (Fw), not the bore diameter of an inner ring. RNA 4903 JNS is designed to operate with the shaft itself serving as the inner raceway.

The catalog limiting speed of 18,000 rpm applies to oil lubrication. For grease lubrication, the manufacturer recommends reducing this value to approximately 60%, equivalent to 10,800 rpm. Actual permissible speed depends on the complete bearing arrangement and operating conditions.

What Does RNA 4903 JNS Mean?

The designation identifies the bearing construction, dimensional series, size code, and manufacturer.

• RNA - Needle roller bearing with a machined outer ring and without an inner ring.

• 49 - Dimensional series within the needle roller bearing range.

• 03 - Bearing size code within the RNA 49 series.

• JNS - Japanese bearing brand manufactured by Nose Seiko Co., Ltd.

The basic designation RNA 4903 does not contain an additional suffix specifying special internal clearance, sealing arrangements, precision class, or a particular cage material.

These characteristics should not be assumed from the designation alone. Where specific internal specifications are required, the corresponding manufacturer documentation should be consulted.

Construction and Operating Principle

RNA 4903 JNS is a radial needle roller bearing consisting of a machined outer ring and a needle roller assembly.

Unlike bearings equipped with an inner ring, RNA 4903 allows the needle rollers to run directly against the shaft surface.

The shaft therefore acts as the inner raceway of the bearing arrangement.

This design reduces the radial installation space required for the bearing and provides radial load support within a compact cross-section.

The main construction characteristics include:

• Machined outer ring with an integrated raceway.

• No separate inner ring.

• Needle-shaped rolling elements.

• Compact radial cross-section.

• Primary suitability for radial loads.

• Compatibility with a separate inner ring when required.

• Open construction requiring appropriate lubrication.

Shaft Raceway Requirements

Because the shaft functions as a rolling contact surface, its material and surface condition directly affect bearing performance.

The shaft raceway must meet the necessary requirements for:

• Surface hardness and wear resistance.

• Surface roughness.

• Roundness and cylindricity.

• Dimensional accuracy.

• Correct operating clearance.

• Lubrication and contamination protection.

An unsuitable shaft raceway may lead to premature wear, damage to the needle rollers, and reduced bearing service life.

If the shaft cannot provide a suitable hardened and ground raceway, a compatible inner ring should be considered.

RNA 4903 JNS is designed primarily to accommodate radial loads. It should not be used as the sole means of axial shaft location.

RNA 4903 JNS vs NA 4903 JNS

RNA 4903 and NA 4903 are related needle roller bearing configurations. Their primary difference is the presence of an inner ring.

The compatible inner ring for RNA 4903 is IR 172213.

When the appropriate inner ring is installed, the resulting bearing arrangement corresponds to the construction of NA 4903.

Before changing between these configurations, verify the shaft diameter, dimensional tolerances, installation space, and axial location.

RNA 4903 and NA 4903 are not automatically interchangeable in an existing bearing arrangement.

Alternative Designations and Reference Numbers

RNA 4903 JNS may also be identified using the following designation formats:

• RNA 4903 JNS

• JNS RNA 4903

• RNA4903 JNS

• JNS RNA4903

The basic designation RNA4903 also appears in bearing catalogs from other manufacturers.

Corresponding bearing series are available from manufacturers such as IKO, INA, NTN, and KOYO.

For example, NTN uses the designation RNA4903R for a related needle roller bearing design.

These references identify potentially comparable bearing types, not guaranteed direct replacements.

Before selecting an alternative, verify the complete dimensions, internal construction, tolerances, load ratings, and operating conditions.

RNA 4903 JNS vs RNA 5903 JNS

RNA 4903 and RNA 5903 belong to related needle roller bearing series without inner rings.

RNA 5903 has a greater width and different load ratings.

The additional width may affect the available installation space, axial positioning, and overall bearing arrangement.

Consequently, RNA 5903 should not be considered a direct replacement for RNA 4903 without verifying the machine design and operating requirements.

Bearing Selection and Interchangeability

Before ordering RNA 4903 JNS, verify the complete designation and technical requirements of the application.

The most important selection criteria include:

• Roller set bore diameter Fw 22 mm.

• Outside diameter D 30 mm.

• Bearing width C 13 mm.

• Shaft raceway hardness and surface finish.

• Shaft and housing dimensional tolerances.

• Required operating clearance.

• Radial load magnitude and distribution.

• Rotational speed.

• Operating temperature.

• Lubrication method.

• Contamination protection.

• Axial location of the bearing assembly.

When replacing an existing bearing, dimensional compatibility must be considered together with internal construction, load ratings, tolerances, and mounting requirements.

Identical nominal dimensions do not necessarily guarantee complete interchangeability between bearings from different manufacturers.

Typical Applications of RNA 4903 Needle Roller Bearings

Needle roller bearings without inner rings are commonly used in mechanical assemblies where the shaft can serve as a hardened and finished raceway.

Typical application categories for this bearing construction include:

• Compact industrial shaft supports.

• Rotating mechanisms in industrial machinery.

• Bearing arrangements with limited radial installation space.

• Mechanical assemblies subjected primarily to radial loads.

• Systems designed for direct contact between needle rollers and a shaft raceway.

These are general applications associated with this bearing design, not verified OEM applications for the specific RNA 4903 JNS part number.

Suitability for a particular machine must be established by evaluating loads, speeds, shaft design, lubrication, and operating conditions.

Installation and Maintenance

Shaft and Housing Preparation

Before installation, inspect the shaft raceway and housing bore for cleanliness, dimensional accuracy, and surface damage.

The shaft raceway must be suitable for direct contact with needle rollers.

Check the surface for corrosion, scoring, deformation, or other defects that could affect bearing operation.

Correct Bearing Installation

When press-fitting the bearing into the housing, apply mounting force to the outer ring.

Do not transmit mounting forces through the needle rollers, as this may damage the rolling elements or raceways.

Correct mounting tools and procedures should be used to avoid misalignment and localized stresses.

Lubrication

RNA 4903 JNS requires appropriate lubrication during operation.

Lubricant selection should account for radial load, rotational speed, temperature, and environmental conditions.

The catalog limiting speed is 18,000 rpm with oil lubrication. Grease lubrication requires a reduced limiting speed according to the manufacturer's guidance.

Actual permissible operating speed depends on the complete bearing arrangement.

Storage

Store the bearing in a clean, dry environment protected from moisture, dust, and other contaminants.

Keep it in its protective packaging until installation whenever possible.

Frequently Asked Questions - RNA 4903 JNS

1. What are the dimensions of RNA 4903 JNS?

RNA 4903 JNS has a roller set bore diameter of 22 mm, an outside diameter of 30 mm, and a width of 13 mm. Its dimensional specification is 22x30x13 mm.

2. Does RNA 4903 JNS include an inner ring?

No. The bearing is designed without an inner ring. Its needle rollers operate directly on a suitably prepared shaft raceway.

3. What is the dynamic load rating of RNA 4903 JNS?

The basic dynamic load rating Cr is 11,800 N according to the JNS catalog data.

4. What is the static load rating of RNA 4903 JNS?

The basic static load rating C0r is 15,600 N.

5. What is the limiting speed of RNA 4903 JNS?

The catalog limiting speed is 18,000 rpm with oil lubrication. Actual permissible speed depends on operating conditions.

6. Which inner ring is compatible with RNA 4903 JNS?

The corresponding inner ring is IR 172213. Correct fits and installation dimensions must be verified before assembly.

7. Are RNA 4903 and NA 4903 identical bearings?

No. RNA 4903 does not include an inner ring, while NA 4903 does. Their shaft diameter requirements and mounting arrangements differ.

8. Can RNA 4903 JNS be replaced with another manufacturer's bearing?

A corresponding bearing may be considered after verifying dimensions, tolerances, internal construction, load ratings, and operating requirements.

RNA 4903 JNS - Key Product Information

RNA 4903 JNS is a radial needle roller bearing manufactured by the Japanese company Nose Seiko. It belongs to the RNA 49 series and has dimensions of 22x30x13 mm. The bearing has no inner ring, allowing the needle rollers to operate directly on a suitable shaft raceway. It primarily supports radial loads. The corresponding inner ring is IR 172213.

RNA 4903 JNS is offered by simmering.pl, a specialist supplier of industrial bearings and mechanical components with a warehouse in Lublin, Poland. The company serves industrial customers, maintenance departments, and technical purchasing teams, providing stock in Poland and international shipping.