RHPLJ-1-1/8Imperial Open Deep Groove Ball Bearing, 1-1/8 x 2-1/2 x 5/8 in, Light Series, Normal Clearance, Pressed-Steel Cage

Product Description

What this part is

A single-row deep groove (radial) ball bearing from RHP’s imperial LJ light series, sized in inches rather than millimetres: 1-1/8 in bore, 2-1/2 in outside diameter, 5/8 in width. In metric terms that is 28.575 x 63.500 x 15.875 mm — close to a metric 6206 but not equal to it, which is the whole reason the series exists. This is the open configuration: no shields, no seals, both faces of the ball complement exposed.

Deep groove ball bearings carry radial load plus moderate axial load in either direction, tolerate high speed and cost little to replace. The LJ series is the inch counterpart to the metric 60xx/62xx light series. It is what you need when the machine was built to British Standard practice and the shaft is an inch dimension. A metric bearing will not drop into an inch housing and onto an inch shaft without shimming or re-machining, so getting the correct LJ number matters more here than on a metric repair.

Reading an RHP imperial number

RHP’s inch-series radial ball bearing code reads prefix, then bore, then variant suffixes. Per NSK-RHP’s own designation-systems document:

LJ — light series single-row radial ball bearing. The J stands for ball journal, RHP’s traditional term for a radial ball bearing.
1-1/8 — the bore, stated directly as an inch fraction. RHP writes this as LJ1.1/8; LJ-1-1/8 and LJ1-1/8 are the same bearing.
No closure suffix — open. This is the point most often got wrong on a re-order, because the sealed and shielded versions share the identical designation stem.

The neighbouring codes in the same family, so you can confirm you are on the right one:

-2RS or -2RSJ — rubber contact seals both sides, greased for life. Better exclusion, more friction, lower speed ceiling.
-ZZ or -2Z — steel shields both sides. A single Z is one shield only.
J as a trailing letter (LJ1.1/8J) — a cage code, not a closure code: pressed-steel, rolling-element-centred. It is the standard cage in this size, so LJ1-1/8 and LJ1.1/8J describe the same open bearing.
XLJ extra light, MJ medium, HJ heavy — different outside diameters and widths on the same bore. MJ1-1/8 is 2-13/16 in OD x 13/16 in wide and will not fit an LJ housing.
KLNJ — small radial ball journal built to BS292 Part 2 standard limits: a different tolerance and section scheme, not simply a smaller LJ.
C2 / CN / C3 / C4 — radial internal clearance. CN is normal and carries no marking, which is why an unsuffixed LJ number is a normal-clearance bearing.

What these specs mean in practice

Open means the bearing has no built-in grease charge and no barrier. That is an advantage, not a compromise, in the applications this series was designed for: an oil-splash or oil-mist gearbox, a circulating-oil headstock, a line-shaft hanger with a grease nipple. Lubricant flows through the bearing, carrying heat and debris out with it. Fit an open bearing into a dry, dirty, unlubricated position and it will fail quickly — if the housing cannot feed it, specify the -2RS sealed version instead.

Normal (CN) radial internal clearance suits a normal shaft and housing fit at moderate temperature. If your shaft fit is a heavy interference, or the inner ring will run appreciably hotter than the housing, the bearing loses clearance in service and you should be looking at C3 instead.

Published ratings and mounting data

Bore: 1.1250 in (1-1/8 in) / 28.575 mm
Outside diameter: 2.5000 in (2-1/2 in) / 63.500 mm
Width: 0.6250 in (5/8 in) / 15.875 mm
Basic dynamic load rating Cr: 20,200 N (20.2 kN)
Basic static load rating Cor: 11,300 N (11.3 kN)
Limiting speed: 11,700 rpm on grease, 15,500 rpm on oil
Radial internal clearance: CN (normal, unmarked)
Rows: 1. Rolling elements: balls. Cage: pressed steel, rolling-element centred
Mass: 0.219 kg (0.483 lb)
Tolerance class: ISO Normal / ABEC 1 for the standard inch-series product
Country of origin: United Kingdom

The load ratings, limiting speeds and mass above are the RHP/NSK catalogue figures for the LJ1.1/8 envelope. SKF’s dimensionally identical RLS 9 is published at Cr 20.3 kN and Cor 11.2 kN — the small differences are internal-geometry differences between the two makers, not a data error, and either bearing is a valid replacement for the other.

Quantity and configuration

Each unit is one bearing, open, loose — not a matched pair and not a set. There is no snap ring, no shields and no seals to remove.

We are holding 158 pieces from one batch. That is worth stating plainly, because depth of stock is a real buying criterion on a repair part: if you need twenty for a gearbox rebuild, forty for a plant-wide bearing change, or a shelf quantity so the next breakdown does not become a lead-time problem, they can all come from the same consistent batch rather than being scraped together from mixed lots of unknown vintage. Volume quantities are available and quoted on request — ask before you order if you need more than the listed quantity, or if you want them shipped as one consolidated lot.

Fitting notes

Verify your shaft and housing are genuinely inch dimensions before ordering. A 28.575 mm bore measures 1.125 in; a metric 30 mm shaft is a different part entirely and there is no LJ number for it.
Press on the ring that takes the interference fit, and never drive load through the balls. On an inner-ring interference fit, push on the inner ring face only; on an outer-ring fit, the outer ring only.
Induction or oil-bath heating of the inner ring to roughly 80°C to 110°C is the clean way to mount an interference fit. Do not exceed about 120°C — the rings are through-hardened bearing steel and will lose hardness above that.
Because it is open, charge the housing with the correct lubricant before running. Do not run it dry even briefly to “check for smoothness”.
Only one ring should be axially clamped if the shaft is long or will grow thermally; leave the other free to float, or the bearing will be preloaded by expansion.

Interchange guidance

RHP was absorbed into NSK and traded for years as NSK-RHP, so an RHP to NSK cross is not a substitution — it is the same product line under the surviving brand. The imperial LJ series is still catalogued.

The industry base number for this envelope is RLS9 (also written RLS 9), used by SKF and followed by most other makers, so RLS9 and LJ1-1/8 are the two names for the same bearing and are worth searching both ways. NKE also lists it as LJ1.1/8.

Things that look like a match and are not: MJ1-1/8 / RMS9 is the medium series on the same bore but a larger OD and width; LRJA1-1/8J is an RHP cylindrical roller bearing that happens to share the 1-1/8 x 2-1/2 x 5/8 in envelope but has completely different load, speed and axial behaviour; LJ1-1/8-2RS / RLS9-2RS1 and LJ1-1/8-ZZ / RLS9-2Z fit the same housing but are sealed and shielded respectively, so they are a functional change rather than a like-for-like swap.