RHP7306ETDUMP4Super Precision Angular Contact Ball Bearing Pair 30x72x19 mm, 25° Contact Angle, Medium Preload, ABEC 7

Product Description

What this part is

A matched pair of super-precision angular contact ball bearings in the 30 mm bore × 72 mm outside diameter × 19 mm width envelope, the ISO 7306 size. Single row each, machined cage, universally ground so the pair reaches its specified medium preload when clamped solid.

Decoding the designation

This part carries two designations and they cross-confirm each other. In 7306ETDUMP4 the E is a 25° contact angle, T the machined phenolic cage, DUM duplex universal with medium preload, and P4 the class equivalent to ABEC 7. In the B-series form 7306X3TDUMEP7 the X3 independently gives the 25° angle and EP7 independently gives the P4 class. Both strings describe the same bearing.

What these specs mean in practice

A 25° contact angle carries more thrust and less speed than a 15° bearing of the same size, and correspondingly less radial load. Medium preload sits between light and heavy: it gives more axial rigidity and tighter shaft location than light preload, without the heat generation that limits heavy preload at speed. Preload is the fact that separates this bearing from its otherwise identical light-preload sibling, and it is set at the factory by the amount of relief ground into the ring faces. The phenolic cage is rated to 120 °C, which sets the practical temperature ceiling. The 19 mm width on a 30 mm bore places this in the heavier 73 dimension series.

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 medium preload with no shimming or hand grinding. The inner rings are clamped solid against one another so the ground relief sets the preload, and the preload is only realised when both outer rings seat fully in the housing bore.

Interchange guidance

RHP super-precision designations cross-reference directly to NSK, which acquired RHP and continued the numbering. The same-spec equivalents are NSK 7306A5TDUMP4, where A5 is the NSK code for 25°, and Timken 3MM306WI CR DUM. The light-preload 7306ETDULP4 and the 15° 7306C share this envelope but are related sizes rather than substitutions.