RHP7308ATDULP4Super Precision Angular Contact Ball Bearing Matched Pair – 40 mm ID, 90 mm OD, 23 mm Width, Open, 25° Contact Angle, Light Preload, ABEC 7, 2 Pcs.

Product Description

What this part is

RHP 7308ATDULP4 super precision angular contact ball bearings, supplied as a factory-matched duplex pair. 40 mm bore, 90 mm outside diameter, 23 mm width per bearing. Open on both faces, phenolic outer-ring-guided cage, 25° contact angle, light preload, ABEC 7 precision. The carton also carries 7308X4TADUEP7 and 3MM308WI CR DUL.

Decoding the designation

7308 gives an angular contact bearing in the 73 dimension series with bore code 08, a 40 mm bore. The 25° contact angle is read from the alternate markings: 3MM in the Fafnir scheme and A5 in the NSK equivalent both denote 25°. T is the fabric-base laminate phenolic cage, matching CR on the Fafnir marking. DU marks a duplex matched set and L light preload. P4 is ISO Class 4, equal to ABEC 7, and EP7 on the third marking says the same.

What these specs mean in practice

The 73 dimension series is the heaviest of the three angular contact series for a given bore, so a 7308 carries markedly more radial and thrust load than a 7208 or 7008 on the same 40 mm shaft. A 25° contact angle adds thrust capacity and axial stiffness over a 15° bearing at some cost in speed. Light preload is the setting chosen where speed and low heat generation matter more than maximum rigidity. The phenolic cage rides on the outer ring land, which keeps it stable and quiet at speed.

Quantity and configuration

2 Pcs, one matched duplex pair, ground so the light preload comes up on assembly with no shimming. The load ratings and limiting speed listed are per bearing.

Fitting notes

Assembly is dry and clean, interference fit on the inner rings, location fit in the housing bore, with both rings clamped fully home against their shoulders so the ground offset closes. The arrangement mark on the outer ring faces sets the orientation. Heat is applied to the shaft rather than the bearing because of the phenolic cage.

Interchange guidance

Another maker’s 40 x 90 x 23 mm 25° duplex pair at light preload and ABEC 7 substitutes directly. A 7308B is a 40° bearing in the same envelope, so it is a related size with different thrust and speed behaviour rather than an interchange. The 7208 and 7008 share the 40 mm bore in lighter series and are likewise related sizes.