NDHSuper Precision Angular Contact Ball Bearing Matched Tandem Pair DT 90x160x30mm 15 Degree ABEC 7 Phenolic Cage Light Preload

Product Description

What this part is

A matched tandem pair of New Departure Hyatt Q-series super-precision angular contact ball bearings on the 7218 envelope: 90 mm bore, 160 mm OD, 30 mm wide each, 60 mm stacked. This is large-spindle hardware — heavy milling and boring spindles, big grinding heads and vertical shafts that carry a substantial one-way thrust at speed.

Decoding the designation

Q — NDH precision angular contact ball bearing line.

20218 — NDH size and design code; the 218 bore code is 90 mm, the 7218 envelope.

DT — duplex tandem, a factory-matched pair mounted facing the same direction.

L — light preload.

The carton cross-references 7218C-T-P4 and Fafnir 2MM218WI-CR agree on 15° contact angle, phenolic cage and P4 / ABEC 7 class.

What these specs mean in practice

In a tandem pair both bearings face the same direction, so their thrust capacities add — roughly double a single bearing — but in one direction only. The shaft still needs a second bearing or a shoulder to locate it the other way. A tandem set mounted back-to-back would give two-way location while throwing away the doubled capacity and the intended load sharing, so the arrangement is not a matter of preference. Light preload keeps friction and heat low, which is what allows a bearing this size to run at speed; the 15° contact angle pushes the speed ceiling higher still at the cost of thrust capacity per bearing, which is exactly why the design stacks two in tandem.

Published specifications

Bore: 90 mm

Outside diameter: 160 mm

Width: 30 mm each bearing

Total width mounted as a tandem pair: 60 mm

Contact angle: 15°

Tolerance class: P4 / ABEC 7

Preload: light

Cage: phenolic

Arrangement: duplex tandem (DT)

Rows: single row each

Closure: open

Dynamic load rating: 129.9 kN

Static load rating: 97.9 kN

Limiting speed: 12000 rpm

Quantity and configuration

Two bearings, supplied as the factory-matched tandem set. Both mount facing the same direction with the high shoulders taking the thrust. The pair is not to be split and a bearing from another set is not a substitute — the even load sharing comes from the matched grind.

Cross-reference guidance

The carton cross-references 7218C-T-P4 and Fafnir 2MM218WI-CR share the 15° angle, phenolic cage and P4 / ABEC 7 class, but the carton lists them as DUL pairs rather than tandem sets. Related but NOT interchangeable: DB or DF pairs of the same size, 7218A5 (25°) or 7218A (30°), medium and heavy preload variants, and any single bearing of this number on its own.