Designation Systems / Four-Point Contact Ball Bearings
Four-Point Contact Ball Bearing Designation System
A four-point contact ball bearing (QJ series) is a single-row ball bearing whose raceway is split — in the QJ design, in the outer ring — so that one bearing carries axial load in both directions. That makes it a locating bearing: it fixes a shaft axially and can replace a matched pair of single-row angular contact bearings. The designation is the basic designation (dimension series + bore code) behind the QJ type code, plus suffixes that describe the locating slots, the internal design and the cage. Four of the five catalogued manufacturers build the type; the tables below put them side by side.
Anatomy of a Designation
QJ 304 N2MA
Example shown in SKF style
QJType code — four-point contact ball bearing (split raceway, axial load in both directions)
3Dimension series 3 (ISO 03, medium)
04Bore code 04 = 20 mm bore
N2Internal design & locating slotsTwo locating slots (notches) in one outer ring side face, 180° apart
MACageMachined brass cage, outer ring centred
Bore code (last two digits of the basic designation)
00 = 10 mm bore01 = 12 mm bore02 = 15 mm bore03 = 17 mm bore04 and up = bore (mm) = code × 52 / 3 / 10 = dimension series written QJ2xx / QJ3xx / QJ10xx (ISO 02 / 03 / 10)
SKF
Internal design & locating slots
| QJ | Four-point contact ball bearing — the split raceway takes axial load in both directions |
| N2 | Two locating slots (notches) in one outer ring side face, 180° apart (SKF table p. 406) |
Cage
| MA | Machined brass cage, outer ring centred |
| PHAS | Glass fibre reinforced PEEK cage with lubrication grooves in the guiding surfaces, outer ring centred |
Series names
| QJ2xx | Light series (ISO dimension series 02) |
| QJ3xx | Medium series (ISO 03) |
NSK
Internal design & locating slots
| (none) | The QJ table prints the basic designation only — QJ + dimension series + bore code (e.g. QJ208, QJ1017) |
Series names
| QJ2xx | Light series (ISO 02) |
| QJ3xx | Medium series (ISO 03) |
| QJ10xx | Light series (ISO 10) |
Schaeffler (FAG)
Internal design & locating slots
| -XL | X-life (higher performance density) design |
| -N2 | Two locating slots in the outer ring |
Cage
| MPA / MP | Solid brass cage |
| TVP | Glass fibre reinforced PA66 cage, ball centred |
Series names
| QJ2xx | Light series (ISO 02) |
| QJ3xx | Medium series (ISO 03) |
| QJ10xx | Light series (ISO 10) |
NTN
Internal design & locating slots
| (none) | The QJ table prints the basic designation only — QJ + dimension series + bore code (e.g. QJ208, QJ1017) |
Series names
| QJ2xx | Light series (ISO 02) |
| QJ3xx | Medium series (ISO 03) |
| QJ10xx | Light series (ISO 10) |
Good to Know
- A four-point contact ball bearing carries axial load in both directions with a single bearing: the raceway is split — in the QJ design, in the outer ring — so each ball contacts it at four points. It is used as a locating bearing, for example in gearboxes, crane sheaves and automotive transmissions.
- The QJ prefix is the type code shared by SKF, Schaeffler (FAG), NSK and NTN: QJ + dimension series + bore code, e.g. QJ304 = ISO 03 (medium) series, 20 mm bore.
- The same size is written differently by each brand: SKF QJ 304 MA (without slots) / QJ 304 N2MA (with locating slots), Schaeffler (FAG) QJ304-XL-MPA, NSK QJ304, NTN QJ304.
- Schaeffler (FAG) prints two designation columns — with and without outer-ring locating slots — and SKF two as well; both writings of one size share the same boundary dimensions and load ratings.
- Timken does not catalogue four-point contact ball bearings in the catalogs in scope, so this page compares the four brands that do.
- The load rating of this type is an axial capacity (the basic dynamic / static load rating of a four-point contact bearing). The catalogues write C / C0 (SKF), Cr / C0r (Schaeffler FAG) and Ca / C0a (NSK, NTN) for the same quantity; the model pages list the figures per brand.
- Cages: SKF uses a machined brass (MA) or a glass fibre reinforced PEEK (PHAS) cage, Schaeffler (FAG) a solid brass (MPA) or glass fibre reinforced PA66 (TVP) cage. The NSK and NTN QJ tables do not print a cage code, so no cage is claimed for them.
- Speeds: SKF publishes a limiting speed only; Schaeffler (FAG) a reference (nr) and a limiting (nG) speed; NSK and NTN grease / oil limiting speeds. The model pages keep the brands' own speed system rather than normalising them.
- Availability of a suffix varies by size — always confirm the exact designation in the manufacturer catalog you are ordering from.
Disclaimer: Data on this page is compiled from publicly available online sources for reference only, and not every model appears in a manufacturer's published catalog. Values may differ between sources and editions — always verify against the manufacturer's current documentation before design or purchase.Full disclaimer →
