JFK K – KBK – KZK needle roller cages

JFK Needle Roller Bearings

Most compact solution
Shaft and housing raceways

Needle roller cages are assemblies of rollers retained by a stamped steel cage, without inner or outer rings: the rollers run directly on the shaft and housing surfaces, which must be hardened and ground. The absence of rings minimizes radial dimensions and allows the maximum number of rollers to be accommodated in the available space, achieving the highest radial load capacity for a given bore diameter.

JFK Group offers needle roller cages in the K series (for applications with cylindrical shaft and housing raceways), KBK series (with smaller rollers for applications with reduced pitch), and KZK series (for applications requiring reduced roller cross-section). Shaft and housing surfaces acting as raceways must be hardened to a minimum hardness of 58 HRC and ground with suitable surface roughness.

Needle roller cages are typically used in applications such as crank mechanisms, connecting rods, oscillating systems, and wherever radial space is the critical parameter and shaft and housing surfaces can be treated.

Versions

Three series: how to choose the right needle roller cage

The choice depends on the bore diameter, the required roller pitch, and the available installation space.

K needle roller cages
The standard series. Stamped steel cage with cylindrical rollers. They operate directly on the shaft and housing surfaces, which must be hardened and ground. K needle roller cages are available in a wide range of sizes. Standard series · Cylindrical rollers · Shaft and housing raceways
KBK needle roller cages
Cage with smaller diameter rollers compared with the K series. KBK needle roller cages are suitable for applications with reduced pitch or where a denser roller arrangement is required. Shaft and housing surfaces must be hardened and ground. Smaller diameter rollers · Reduced pitch · Denser arrangement
KZK needle roller cages
Cage with reduced cross-section rollers for applications requiring extremely limited installation space. Shaft and housing surfaces for KZK needle roller cages must be hardened and ground. Reduced cross-section rollers · Extremely limited installation space · Shaft and housing raceways

Performances

Design and performance features

Ringless design for minimum installation space and maximum radial load capacity within the available envelope.

Benefit

Speed

Low and medium rotational speeds Suitable for low and medium speeds, typical of crank applications and oscillating systems. For higher speeds, needle roller bearings with drawn cups or NK/NKI needle roller bearings should be considered.

Benefit

Cages

Stamped steel Stamped steel cages for all series. The cage retains the rollers and ensures their uniform distribution along the running surface.

Benefit

Load

Maximum radial load capacity for the available space The absence of rings and the maximum number of rollers within the available space ensure the highest radial load capacity for a given envelope. Suitable for high radial loads in extremely limited spaces.

Benefit

Installation space

Most compact solution available Without inner and outer rings, needle roller cages provide the smallest possible radial dimensions. The ideal solution when space is the primary constraint and shaft and housing surfaces can be treated.

Benefit

Raceways

On shaft and housing The shaft and housing surfaces act directly as raceways. They must be hardened to a minimum hardness of 58 HRC and ground with suitable surface roughness to ensure the expected performance.

Benefit

Lubrication

Lubrication must be ensured before commissioning and periodically during operation through the lubrication channels on the shaft or housing.

Mounting

Mounting of needle roller cages

Needle roller cages are installed directly between the shaft and housing surfaces, which must be hardened and ground beforehand. Before installation, verify that the surfaces meet the required tolerances, hardness, and roughness specifications. Lubrication must be ensured before commissioning.

Installation Mounting

Installation between shaft and housingThe cage with rollers is positioned directly between the already treated shaft and housing surfaces. No special tools are required, but the surfaces must be properly prepared.
Surface inspectionBefore installation, check the hardness (min. 58 HRC), dimensional tolerances, and surface roughness of the shaft and housing. Non-compliant surfaces may compromise performance and operating life.

Technical data

Speed: Low and medium rotational speeds
Cages: Stamped steel
Load: Maximum radial load capacity for the available space
Installation space: Most compact solution available
Raceways: On shaft and housing

Applications

Components and application support for every industrial environment.

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JFK Needle Roller Bearings

Contacts

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Related products

Please also consider these alternatives: When shaft and housing surfaces cannot be treated, NK/NKI needle roller bearings provide the same load capacity with their own rings. For applications with higher speeds or where an integrated stamped outer ring solution is preferred, drawn cup needle roller bearings offer simplified installation. When needle roller cages are to be used on untreated shafts, the IR inner ring allows the shaft hardening process to be avoided.