FAGL15RA500YPThin Section Angular Contact Ball Bearing 5.000 x 5.625 x 5/16 in, Type A Single-Direction Thrust, Open, Brass Separator

Product Description

What this part is

This is a thin section (light section) angular contact ball bearing measuring 5.000 in bore x 5.625 in outside diameter x 5/16 in (0.3125 in) wide. It sits in the inch-envelope thin section family that most engineers know through the Kaydon Reali-Slim and Silverthin numbering systems, and it is the direct equivalent of Kaydon KB050AR0 and Silverthin SB050AR0. It is an open bearing — no seals, no shields — with a single row of 5/32 in balls in a one-piece machined brass pocket separator, built to ABEC Class 1.

Decoding the designation

L — thin section / light section bearing family15 — cross-section code for the 5/16 in x 5/16 in square section, the same envelope as the Kaydon “B” and Silverthin “B” sectionR — open, unsealed, with a retainer (separator)A — angular contact, single row, thrust-capable in one direction (Type A)500 — bore in hundredths of an inch, so 5.000 inYP — FAG separator suffix for a one-piece machined pocket-type brass separator, the same construction the trailing R0 denotes in Kaydon KB050AR0 and Silverthin SB050AR0

The square cross section, proved from the numbers

Outside diameter minus bore is 5.625 − 5.000 = 0.625 in, leaving 0.3125 in of wall on each side. That is exactly the 5/16 in race width, so the cross section is a true 5/16 x 5/16 in square. It is a useful sanity check: if the wall per side equals the stated width, the thin section envelope is right, and you do not need a datasheet in hand to confirm it. The 7.000 in bore sibling in this series checks out identically — 7.625 − 7.000 = 0.625 in — because the section stays constant while the diameter grows.

What these specs mean in practice

A thin section bearing trades load capacity for envelope and mass. Compared with a conventional ball bearing of the same outside diameter you accept a much lower rating in exchange for a very thin radial wall and a very large open bore. The design driver is nearly always something that must pass down the centre: a hollow shaft, a cable bundle, a slip ring, an optical path, a fluid line. Hence the concentration of these bearings in robotics joints, gimbals, rotary and index tables, medical imaging gantries, semiconductor wafer handlers, and optical and radar positioners.

The balls here are 5/32 in diameter — the same size used in the 7.000 in bore version of this series. Thin section families keep ball diameter constant across the bore range and add ball count as the pitch circle grows, which is why capacity rises only modestly with diameter instead of scaling the way it does in a conventional bearing series. Size on the published rating, not on how large the bearing looks.

Published ratings and mounting data

Static radial load capacity: 2,500 lbfDynamic radial load capacity: 975 lbfStatic thrust load capacity: 7,210 lbfDynamic thrust load capacity: 2,410 lbfLand diameters: L1 5.231 in, L2 5.393 in, L3 5.460 inBall diameter: 5/32 inMaximum fillet radius cleared: 0.040 inRace width tolerance: +0.000 / −0.005 inPrecision: ABEC Class 1Weight: 0.38 lb

These radial and thrust capacities are not additive. If the bearing sees radial and thrust load simultaneously, the resultant has to be checked against a combined-load calculation — measuring it against either column alone will overstate what the bearing will actually survive. Ball count and nominal contact angle are not published for this part and have deliberately been left out rather than estimated. Kaydon Type A geometry is often quoted as roughly 30°, but that number is absent from the published datasheet and should be treated as unverified.

Quantity and configuration

Twelve pieces are on hand. Thin section bearings usually surface as one-off spares, so a lot of twelve from a single batch is genuinely unusual: it is enough to fit every axis of a multi-axis machine, or to rebuild a positioner and still hold same-batch spares. Central Surplus also stocks the 7.000 in bore sibling from this series, L15RA700YP (Kaydon KB070AR0 / Silverthin SB070AR0), with five pieces on hand — so an assembly that uses both sizes can be matched from one source.

Fitting notes

Thin rings are flexible rings. A thin section bearing will faithfully assume the out-of-roundness of whatever you clamp it into, and that is by far the most common cause of premature failure in this class of bearing. Housing bores and shaft seats must be machined round and flat to a tighter standard than a conventional bearing would forgive, the surrounding structure needs to be rigid, and clamping load should be applied uniformly around the circumference rather than pulled up through a few bolts. Respect the 0.040 in maximum fillet radius at shaft and housing shoulders.

Type A angular contact carries thrust in one direction only. Fit a single Type A bearing where thrust reverses and it will unload on the reverse stroke; reversing thrust calls for a duplex pair (BR0 back-to-back or FR0 face-to-face) or a four-point contact bearing (XP0). Because this bearing is open it also has no lubricant retention of its own — greasing and sealing are the job of the surrounding design.

Interchange guidance

Direct equivalents: Kaydon KB050AR0, Silverthin SB050AR0, INA CSEB050, SKF FPAB500, NSK NBA12707, NTN KYB050, SSB RB050AR0, RBC KB050AR0. FAG and INA are both Schaeffler Group brands, so INA CSEB050 is the in-house sibling rather than an outside substitute.

Related but functionally different, and not substitutes: SB050CP0 (radial contact), SB050XP0 (four-point contact), JSB050CP0 and JSB050XP0 (sealed versions), SB050BR0 (duplex back-to-back) and SB050FR0 (duplex face-to-face). Each changes contact geometry, sealing or thrust direction capability, so none of them drops into a Type A open application without a fresh look at the load case.