NTN K 21x25x17 Needle Roller Cage Assembly

Applications - Compact Industrial Systems

The NTN K 21x25x17 needle roller cage assembly is designed for applications where high radial load capacity is required within limited installation space. This type of needle roller bearing assembly operates without inner and outer rings, allowing direct contact with a hardened shaft and housing raceway to form a compact bearing unit.

It is widely used in gearboxes, transmissions, agricultural machinery, drive systems, and various industrial applications where space optimization and load performance are critical. Compared to a standard ball bearing, this needle roller solution provides significantly higher radial load capacity within the same radial envelope.

Advantages - High Load Performance and Compact Design

Manufactured by NTN, the K 21x25x17 assembly ensures precision geometry and reliable operation. The needle rollers provide a larger contact surface area with the raceway, which improves load distribution and increases durability under heavy radial loads.

Because it does not include integrated rings, the assembly reduces overall mass and enables flexible design integration. When installed in a properly machined bearing housing, it forms a rigid and efficient bearing unit suitable for continuous-duty industrial operation.

Technical Specifications

• Model: K 21x25x17

• Brand: NTN

• Type: Needle roller cage assembly (without rings)

• Inner diameter: 21 mm

• Outer diameter: 25 mm

• Width: 17 mm

• Load type: Radial loads

• Application: Industrial machinery, gear systems, drive units

Main Description

The NTN K 21x25x17 needle roller cage assembly is engineered for compact mechanical systems requiring high radial load support and minimal radial space. Its needle roller configuration increases the effective load-carrying surface compared to many traditional bearing solutions.

Unlike a typical ball bearing, this assembly relies on hardened and precision-ground shaft and housing surfaces to function as raceways. This design provides improved stiffness and high durability when correctly installed and lubricated.

The K 21x25x17 is commonly selected for industrial drive systems, transmission mechanisms, and equipment operating under dynamic load conditions. It supports reliable shaft guidance while maintaining compact dimensions, making it ideal for OEM production and maintenance environments where efficiency and mechanical reliability are essential.

FAQ - Frequently Asked Questions

What is the difference between a needle roller assembly and a ball bearing?
A needle roller assembly supports higher radial loads in a smaller radial space compared to a ball bearing.

Does the K 21x25x17 include inner and outer rings?
No, it is a cage assembly without rings and requires hardened raceways.

What loads can it support?
It is designed primarily for radial loads.

Is it suitable for industrial applications?
Yes, it is widely used in gearboxes, machinery, and drive systems.

Does it require specific housing preparation?
Yes, the shaft and housing must be properly hardened and machined to function as raceways.