NSK7209CTRDULP3Super Precision Angular Contact Ball Bearing Pair 45x85x19 mm, 15° Contact Angle, Phenolic Cage, Light Preload

Product Description

What this part is

A matched pair of super-precision angular contact ball bearings in the 45 mm bore × 85 mm outside diameter × 19 mm width envelope, the ISO 7209 size. Single row each, phenolic cage, universally ground so the pair reaches its specified preload when clamped solid.

Decoding the designation

In the NSK super-precision scheme C is a 15° contact angle, distinct from A at 30° and A5 at 25°, so a 7209C and a 7209A5 are different bearings sharing one envelope. TR is the machined phenolic cage guided on the outer ring land. DUL is duplex universal with light preload, and P3 is the NSK precision class marking carried on the carton.

What these specs mean in practice

A 15° contact angle carries more radial load and runs faster than a 25° or 30° bearing of the same size, and carries correspondingly less thrust. Light preload removes internal play and fixes the contact angle while adding the least heat of the three preload grades, which keeps axial position and runout repeatable without penalising speed.

The phenolic cage guided on the outer ring land is the high-speed cage arrangement. Phenolic is light, so cage inertia and ball-pocket loads stay low, and it holds an oil film well; land guidance keeps the cage running true at speed rather than wandering on the ball set. Phenolic sets the temperature ceiling at roughly 120 °C, which governs ahead of the steel.

Thrust direction

Each bearing carries radial load together with thrust in one direction only. Mounted back-to-back or face-to-face the pair locates the shaft axially in both directions, one row acting in each; mounted in tandem both act in the same direction at roughly doubled capacity.

Quantity and configuration

2 Pcs. One universally ground pair, 38 mm total width when clamped solid, supplied without spacers, locknut or housing.

Fitting notes

Universal grinding means the two rings stack back-to-back, face-to-face or in tandem and arrive at the specified light preload with no shimming or hand grinding. The pair is assembled in the orientation its face marks indicate and the inner rings are clamped solid against one another so the ground relief sets the preload. Seats at this class are ground and measured, and the preload is only realised when both outer rings seat fully in the housing bore.

Interchange guidance

NSK acquired RHP and continued its numbering, so the RHP form 7209CTDULP4 is the direct counterpart designation. The Fafnir-scheme equivalent is Timken 2MM209WI CR DUL, the 2MM prefix likewise denoting 15°. A 7209 in this envelope at 25° or 40°, or at a medium or heavy preload grade, is a related size rather than a substitution.