NSK5305ZZTNGC3Double Row Angular Contact Ball Bearing, 25 x 62 x 25.4 mm, Shielded Both Sides, C3 Clearance

Product Description

What this part is

An NSK double row angular contact ball bearing at the 5305 envelope: 25 mm bore, 62 mm outside diameter, 25.4 mm (1 in) wide, with metal shields on both faces and C3 internal clearance. Two rows of balls run on angled raceways inside one pair of rings, which is what lets a single bearing carry radial load and take thrust in both directions — the job that otherwise needs two opposed single-row bearings and a setting operation at assembly.

Decoding the designation — and reading NSK’s scheme, not the industry’s:
Suffix letters mean different things at different manufacturers, so it matters that this is an NSK bearing read against NSK’s own convention.

5305: double row angular contact ball bearing, medium 5300 series. The same envelope is also designated 3305 under the older numbering.

ZZ: metal shields on both sides, in NSK’s scheme. NSK uses Z and ZZ for shields and D, DU, DW and V for contact and non-contact seals. This is worth stating explicitly because the convention is not universal: MRC, for one, uses ZZ to mean rubber seals. If you are cross-shopping brands on the suffix alone you can end up with a completely different closure.

TNG: NSK’s moulded-polymer cage family. TN designates a polyamide cage. This is a moulded-polymer cage bearing rather than a pressed-steel or machined-brass one.

C3: internal clearance greater than normal, per the ISO clearance classes.

Why C3 clearance is the specification to check first:
C3 is not a quality grade — it is a fitted-clearance decision, and it fails in both directions if mismatched. Internal clearance shrinks once the bearing is installed, because an interference fit on the shaft expands the inner ring and a tight housing fit compresses the outer ring. It shrinks further in service as the inner ring runs hotter than the outer and grows more. C3 exists to leave headroom for both effects.

So: fit a normal-clearance bearing where C3 was specified and, once it is pressed on and up to temperature, the balls can end up preloaded against raceways that were never designed to carry a preload. It runs hot, and hotter means less clearance still, which is a runaway. Conversely, fit C3 where normal clearance was specified and in a lightly loaded, cool-running, slip-fitted application the balls may not be properly constrained — you get noise, ball skidding rather than rolling, and accelerated wear.

C3 is the right instinct for a heavy interference fit, a hot environment, or a bearing whose inner ring will run substantially warmer than its housing.

What the shields do

Metal shields are a non-contact closure: they run with a small clearance to the inner ring rather than rubbing on it. That means near-zero added friction and no speed penalty, and the bearing arrives greased and needs no relubrication provision. Shields exclude solid debris. In a washdown environment, a coolant mist, or anywhere the bearing sits in a liquid path, a contact-sealed bearing is the correct choice. For dry, enclosed, moderately dirty machinery — which is most of it — shields are the right answer and the lower-friction one.

Published ratings for this envelope

The figures below are the widely published ratings for the open 5305 envelope across the trade, indicative of the size.

Bore (d): 25 mm.

Outside diameter (D): 62 mm.

Width: 25.4 mm / 1.000 in.

Dynamic radial load rating: 32,000 N (open 5305 envelope).

Static radial load rating: 21,600 N (open 5305 envelope).

Limiting speed, grease: 7,300 rpm (open 5305 envelope).

Limiting speed, oil: 10,000 rpm (open 5305 envelope).

Internal clearance: C3.

Closure: shielded both sides (ZZ).

Cage: moulded polymer (TN family).

Number of rows: 2.

The shielded version is thermally limited by its grease rather than by its geometry, so treat the grease figure as the ceiling.

Quantity and configuration

Sold individually. Each is a complete bearing that locates a shaft in both axial directions on its own — a single double-row unit, not half of a matched pair.

Interchange guidance

Search forms include 5305ZZTNGC3, 5305-ZZ-TNG-C3, 5305 ZZ TNG C3, 5305ZZ, 5305ZZC3, 5305, 3305, 3305ZZ and 5305-2Z. Same-envelope alternatives at 25 × 62 × 25.4 mm are catalogued by Timken/Fafnir (5305KG, 20°), MRC/SKF (5305MG and 5305CG, 30°), NTN (5305) and Nachi (5305), plus 5305-2RS and 5305ZZ from general-line suppliers. Verify contact angle, closure type and clearance class before treating any of them as a drop-in.