NTNPrecision Angular Contact Ball Bearing 60x130x31 mm, 30 Degree Contact Angle, Machined Phenolic Cage, Back-to-Back Duplex Arrangement

Product Description

What this part is

An NTN precision angular contact ball bearing in the heavy 73-dimension series, 60 mm bore × 130 mm outside diameter × 31 mm width, 30° contact angle, fitted with a machined phenolic cage and supplied in a back-to-back duplex arrangement.

Decoding the designation

7312 is the 73-dimension series angular contact envelope, 60 x 130 x 31 mm. With no angle suffix, NTN’s standard contact angle for this series is 30°. T1 is NTN’s own published phenolic cage code — NTN’s default is an unmarked pressed-steel cage, J is pressed steel, L1 is machined brass and T2 is moulded resin, so T1 puts this bearing in the machine tool and high-speed category. DB is a back-to-back duplex arrangement, with the load lines diverging outward for high moment and tilting resistance. The carton also carries G03 and PM, which are retained here as search terms.

What 30° with a phenolic cage means in practice:
30° is the thrust-biased end of the general-purpose angular contact range: high axial capacity and axial stiffness, good resistance to thrust reversal, at the cost of speed and heat compared with a 15° or 25° bearing. The phenolic cage partly offsets that penalty, riding light and damping ball-passage excitation; it tolerates marginal lubrication far better than steel or brass and allows higher dN values, which is why it appears on machine tool and high-speed positions. Contact Angle: 30°. Cage Material: Phenolic. Dynamic Load Rating: 109 kN (single bearing), 176 kN as a DB pair. Static Load Rating: 71.5 kN (single bearing), 143 kN as a DB pair. Limiting Speed: 5,900 rpm grease / 7,900 rpm oil, single bearing.

Mounting data

Axial load centre offset a: 43 mm. Chamfer rs / r1s minimum: 2.1 mm / 1.1 mm. Shaft abutment diameters: da 72 mm, db 67 mm. Housing abutment diameters: Da 118 mm, Db 123 mm. Mass: 1.74 kg per bearing.

Quantity and configuration

DB denotes a matched back-to-back pair.

Interchange guidance

The same envelope and 30° angle in other schemes: 7312A in NSK format where A denotes 30°, 7312 in FAG format, and 7312BECBM in SKF format — the SKF B suffix denotes 40°, so an SKF 7312B is not angle-equivalent to this bearing. Within this envelope, 7312C is 15° and 7312B is 40°, and neither substitutes for a 30° part. The carton marking 2MM312 WI CR DUL is a search term only: the Fafnir 2MM prefix denotes 15°, so it is not an angle equivalent to this 30° NTN part, and DUL is a preload class rather than the DB arrangement carried here. NTN remains the current source.