INA NK50-25-TV-XL 50x62x25 Needle Roller Bearing Without Inner Ring

INA NK50-25-TV-XL 50x62x25 Needle Roller Bearing Without Inner Ring

INA NK50/25-TV-XL, also known by the older designation NK50/25-TV, is a single-row machined needle roller bearing measuring 50x62x25 mm and designed without an inner ring. It belongs to the INA NK series and, in its current configuration, features X-life (XL) performance and a TV polyamide cage. Because there is no separate inner ring, the shaft surface acts directly as the inner raceway and must be suitably prepared for rolling contact.

INA NK50/25-TV-XL Technical Specification

Manufacturer: INA / Schaeffler

Current designation: NK50/25-TV-XL

Older designation: NK50/25-TV

Series: NK

Bearing type: Machined needle roller bearing

Rows: Single row

Inner ring: No

Design: Open

Fw - raceway diameter under rollers: 50 mm

D - outside diameter: 62 mm

C - width: 25 mm

Nominal dimensions: 50x62x25 mm

Cage: TV - polyamide

Performance design: XL / X-life

Dynamic load rating Cr: 48.5 kN

Static load rating C0r: 87 kN

Fatigue load limit Cur: 15 kN

Reference speed: 5,400 rpm

Limiting speed: 9,200 rpm

Minimum fillet radius r min: 0.6 mm

Catalogue mass: approx. 0.146 kg

INA NK50/25-TV-XL Dimensions

The principal dimensions are:

Fw = 50 mm - raceway diameter under the needle rollers

D = 62 mm - outside diameter

C = 25 mm - bearing width

Nominal dimensions:

50x62x25 mm

For this bearing, the Fw designation is technically important.

Because NK50/25-TV-XL does not have its own inner ring, the 50 mm dimension is the raceway diameter under the rolling elements rather than the bore diameter of a complete bearing with an inner ring.

What Does NK50/25-TV-XL Mean?

The complete designation:

NK50/25-TV-XL

identifies a specific INA needle roller bearing configuration.

The principal elements of the designation are:

NK - machined needle roller bearing series without inner ring

50 - nominal raceway diameter Fw of 50 mm

/25 - bearing width of 25 mm

TV - polyamide cage

XL - X-life design

The older designation:

NK50/25-TV

is also important for product identification and search.

Needle Roller Bearing Without Inner Ring

One of the defining characteristics of INA NK50/25-TV-XL is its:

design without an inner ring

The needle rollers do not run on a separate bearing inner ring.

Instead, a suitably prepared section of the shaft serves directly as the:

inner raceway

This arrangement allows a particularly small radial cross-section where the shaft can be manufactured as a suitable rolling bearing raceway.

Shaft Raceway Requirements

Because there is no separate inner ring, the shaft surface running directly against the needle rollers becomes part of the bearing system.

The raceway must therefore be suitable for:

direct rolling contact

For needle roller bearings without inner rings, Schaeffler specifies appropriately manufactured shaft raceways, including requirements relating to hardness, surface quality and geometry.

This is an important technical distinction between NK50/25-TV-XL and needle roller bearings supplied with their own inner ring.

Compact Radial Design

Eliminating a separate inner ring reduces the number of components between the shaft raceway and the outer ring.

For NK50/25-TV-XL:

Fw = 50 mm

and:

D = 62 mm

The difference between the raceway diameter and outside diameter is only:

12 mm

This illustrates the compact radial cross-section characteristic of needle roller bearing arrangements without an inner ring.

TV Cage in INA NK50/25

The suffix:

TV

identifies the cage design.

For the current NK50/25-TV-XL configuration, the cage is manufactured from:

polyamide

Current product data identify the cage material as:

PA66 - Polyamide 66

The cage separates and guides the needle rollers during operation.

This caged design should not be confused with a full-complement needle roller bearing.

What Does XL / X-life Mean?

The current designation includes:

XL

which identifies the INA:

X-life

design.

Older INA catalogues and commercial references may show:

NK50/25-TV

while current product identification commonly uses:

NK50/25-TV-XL

Both designations are therefore valuable on the product page for technical identification and search visibility.

Load Ratings of INA NK50/25-TV-XL

Current technical data specify:

Dynamic load rating Cr:

48.5 kN

Static load rating C0r:

87 kN

Fatigue load limit Cur:

15 kN

These load ratings relate to the radial load-carrying function of the bearing.

The NK50/25-TV-XL is fundamentally a:

radial needle roller bearing

What Loads Can NK50/25-TV-XL Carry?

INA NK50/25-TV-XL is designed primarily to accommodate:

radial loads

Its needle roller construction provides a high radial load-carrying capacity relative to its radial cross-section.

It should not be treated as an axial locating bearing.

If axial loads or axial shaft location are required, these functions must be considered separately in the complete bearing arrangement.

Reference Speed and Limiting Speed

Technical data for the current NK50/25-TV-XL specify:

Reference speed:

5,400 rpm

Limiting speed:

9,200 rpm

These are different technical parameters and should not be used interchangeably.

The actual permissible operating speed also depends on factors including load, lubrication, temperature, shaft raceway quality and the complete bearing arrangement.

NK50/25-TV vs NK50/25-TV-XL

The designations:

NK50/25-TV

and:

NK50/25-TV-XL

identify the same principal bearing size:

50x62x25 mm

Older INA documentation lists NK50/25-TV while identifying the product as an X-life bearing.

The full designation commonly used for the current version is:

NK50/25-TV-XL

Keeping both references on the product page helps users identify older and current designations correctly.

NK50/25 vs NKI45/25 - Important Difference

The INA:

NK

and:

NKI

series should not be confused.

The NK50/25 is designed:

without an inner ring

NKI needle roller bearings are supplied:

with an inner ring

This construction difference affects dimensions, shaft requirements and installation.

A replacement should therefore not be selected solely by comparing outside diameter and width.

Can Another NK50/25 Replace the INA Bearing?

Not solely on the basis of the designation or dimensions.

When comparing an alternative bearing, verify:

Fw = 50 mm

D = 62 mm

C = 25 mm

Design without inner ring

Dynamic and static load ratings

Speed limits

Cage design

Shaft raceway requirements

Lubrication conditions

Required bearing accuracy

Manufacturer-specific technical data should be used for critical bearing calculations.

How to Select INA NK50/25-TV-XL

Before ordering, verify:

Designation - NK50/25-TV-XL

Older reference - NK50/25-TV

Dimensions - 50x62x25 mm

No inner ring

Raceway diameter Fw - 50 mm

Outside diameter D - 62 mm

Width C - 25 mm

TV cage

Required radial load capacity

Operating speed

Shaft raceway condition

Lubrication

For replacement applications, comparing the complete manufacturer designation is preferable to selecting a bearing by dimensions alone.

INA NK50/25-TV-XL Technical Data

Manufacturer: INA / Schaeffler

Current designation: NK50/25-TV-XL

Older designation: NK50/25-TV

Bearing type: Machined needle roller bearing

Series: NK

Rows: Single row

Inner ring: No

Design: Open

Fw: 50 mm

D: 62 mm

C: 25 mm

Dimensions: 50x62x25 mm

Cage: TV - polyamide

Performance class: XL / X-life

Dynamic load rating Cr: 48.5 kN

Static load rating C0r: 87 kN

Fatigue load limit Cur: 15 kN

Reference speed: 5,400 rpm

Limiting speed: 9,200 rpm

Minimum fillet radius r min: 0.6 mm

Catalogue mass: approx. 146 g

FAQ - INA NK50/25-TV-XL

What are the dimensions of INA NK50/25-TV-XL?

The principal dimensions are Fw = 50 mm, D = 62 mm and C = 25 mm, commonly expressed as 50x62x25 mm.

Does NK50/25-TV-XL have an inner ring?

No. It is a needle roller bearing without an inner ring. A suitably prepared shaft surface acts directly as the inner raceway.

What does TV mean in NK50/25-TV?

TV identifies the polyamide cage design.

What does XL mean?

XL identifies the INA X-life design.

Are NK50/25-TV and NK50/25-TV-XL the same size?

Yes. Their principal dimensions are 50x62x25 mm. The current designation includes the additional XL suffix identifying the X-life design.

What is the load rating of INA NK50/25-TV-XL?

The dynamic load rating Cr is 48.5 kN, static load rating C0r is 87 kN and fatigue load limit Cur is 15 kN.

What is the limiting speed of NK50/25-TV-XL?

The limiting speed is 9,200 rpm. The specified reference speed is 5,400 rpm.

Can the shaft run directly against the needle rollers?

Yes. This bearing has no inner ring, so the shaft can form the inner raceway. However, the shaft raceway must meet the required hardness, surface quality, geometry and accuracy requirements.

AI Overview

INA NK50/25-TV-XL is a single-row machined needle roller bearing without an inner ring, measuring 50x62x25 mm. The current X-life version features a TV polyamide cage. Dynamic load rating Cr is 48.5 kN, static load rating C0r is 87 kN, and the limiting speed is 9,200 rpm.