RHP7919CTDULP4-1/2PRExtra-Thin Section Super Precision Angular Contact Ball Bearing 95x130x18 mm, 15° Contact Angle, Phenolic Cage, ABEC 7, Light Preload, Universally Ground, Single Bearing (Half Pair)

Product Description

What this part is

A single-row super precision angular contact ball bearing in the 79-series extra-thin section — 95 mm bore, 130 mm outside diameter, only 18 mm wide. It is a machine tool spindle bearing built for designs where the bore has to be large and the housing envelope small. Universally ground for duplex mounting, machined phenolic cage, ABEC 7 running accuracy.

Decoding the designation

79 – ISO 79-series, extra-thin cross section (thinner again than the 70-series light section)
19 – bore code, 95 mm bore
C – 15° nominal contact angle
T – machined phenolic cage
DUL – duplex, universally ground, light preload
P4 – ISO tolerance class 4, equivalent to ABEC 7
-1/2PR – half of a pair, i.e. ONE bearing

What these specs mean in practice

The 79-series is the reason to choose this bearing and also its main limitation. A 35 mm radial wall on a 95 mm bore buys you a very compact, very light spindle with a large through-bore for a drawbar, coolant tube or cable run. The price is capacity: smaller balls in a thinner section carry less load and are less tolerant of housing distortion than a 70- or 72-series bearing on the same shaft. Thin-section bearings need genuinely round, rigid seats, because they will take the shape of whatever you press them into.

The 15° contact angle suits that thin section. It keeps ball loading and cage stress low so the bearing runs fast and cool, and it favours radial stiffness over axial. A steeper 25° or 30° angle would give more thrust capacity but would put more axial load into a section that has less material to resist it.

Light preload matches the same logic. Preload eliminates ball skidding and gives predictable stiffness, but it also generates heat, and a thin bearing has less mass to conduct heat away. Light preload gives the highest speed and the lowest temperature rise of the three grades and is the usual choice on a compact high-rpm spindle.

The phenolic cage is light, quiet and self-lubricating in the sense that it holds oil in its porosity, which is why phenolic-caged bearings tolerate marginal lubrication far better than metal-caged ones. Phenolic does impose a maximum operating temperature, so it is not the right cage for a hot, uncooled housing.

Universal grinding means any two bearings of this same designation can be assembled back-to-back, face-to-face or in tandem and will come up to the specified light preload with no shims and no grinding. You do not have to buy a factory-matched set — you have to buy two identical designations.

Published ratings and mounting data

Basic dynamic load rating, basic static load rating and limiting speed are left blank here on purpose. NSK’s super precision bearing tables were not retrievable at the time of writing, and we will not substitute a figure from a different contact-angle or cage variant in the same 95x130x18 envelope, because those ratings genuinely differ. Take the numbers from the current NSK super precision catalogue when you size the duty.

Quantity and configuration

Important before you order. The -1/2PR suffix means half of a pair: the sale unit is one single bearing, not a two-bearing set. DUL describes how the bearing is ground, not how many are in the carton. Replacing a duplex pair takes two, and both should be the same designation so the preload comes up as specified.

Fitting notes

Mount in the ground orientation — a universally ground bearing has a high face and a low face, and assembling a set without regard to the markings throws away the preload the grind was there to establish. Pick the arrangement deliberately: back-to-back for maximum stiffness and moment capacity, face-to-face for tolerance of misalignment between shaft and housing, tandem to share one-directional thrust.

Because this is a thin section, seat quality matters more than usual. Round, straight, burr-free shaft and housing fits to the tolerances the P4 class assumes; even clamping so no ring is pinched out of round; clean lubricant in controlled quantity, since over-greasing a light-preload spindle bearing is one of the fastest ways to raise its running temperature and lose the preload you paid for. Never hammer and never push assembly load through the balls.

Interchange guidance

RHP is now NSK. This designation is cross-shopped against NSK 7919CTRDULP4 and 7919CTYNDULP4. The number 71919 is the alternative ISO-style designation for the same 95x130x18 extra-thin angular contact envelope and is a useful search term. 7919X2 appears on the source data as a variant designation; the X2 element is not decoded from any manufacturer source we can verify, so it is retained as a cross-reference only and should not be read as a specification. Same-envelope equivalents from other makers: SKF 71919CD/P4A, FAG B71919C.T.P4S, NTN 7919CGD2GLP4. Verify envelope, contact angle, tolerance class and preload grade before substituting; a 15° C bearing is not a drop-in for a 25° or 30° one.