Bearing decoder

A 6205-2RS1 C3 is a deep groove ball bearing, 25 mm bore, 52 mm outside diameter and 15 mm wide, with a rubber contact seal on both sides and C3 clearance: 13 to 28 µm of radial play before it is fitted. Type a bearing number for its type, bore, sizes, seals or shields, clearance and precision class, or add the load rating, load and speed for its basic L10 life.

The bearing is drawn in section with the parts the number names. d, D and B are to size where the tables hold the series.

Bearing number

Load rating C

Load P

Speed n

Deep groove ball bearing6205 2RS1 C3

Deep groove ball bearing

Radial load, and some axial load either way. Dimension series (0)2: width 0 (left out of the number), diameter 2.

Bore d 25 mm

Bore code × 5: 05 × 5 = 25 mm.

D × B

52 × 15 mm

Outside diameter and width from the boundary dimension tables (ISO 15).

2RS1

Contact seal, NBR, both sides (SKF)

A rubber lip pressing on the inner ring.

Radial internal clearance greater than Normal

More play than Normal. For d 25 mm: 13 to 28 µm (ISO 5753-1).

How it’s calculated

$L_{10} = (\frac{C}{P})^{p} L_{10 h} = \frac{1 0 ^{6}}{60 n} L_{10}$ ISO 281 basic rating life, in millions of revolutions and in hours at n r/min: C is the maker’s basic dynamic load rating for that bearing, P the equivalent dynamic load, p = 3 for ball bearings and 10/3 for roller bearings. Nine in ten bearings reach it.

Bore code	d	Series 10 (60, 70): D × B	Series 02 (62, 72, N2): D × B	Series 03 (63, 73, N3): D × B
00	10	26 × 8	30 × 9	35 × 11
01	12	28 × 8	32 × 10	37 × 12
02	15	32 × 9	35 × 11	42 × 13
03	17	35 × 10	40 × 12	47 × 14
04	20	42 × 12	47 × 14	52 × 15
05	25	47 × 12	52 × 15	62 × 17
06	30	55 × 13	62 × 16	72 × 19
07	35	62 × 14	72 × 17	80 × 21
08	40	68 × 15	80 × 18	90 × 23
09	45	75 × 16	85 × 19	100 × 25
10	50	80 × 16	90 × 20	110 × 27
11	55	90 × 18	100 × 21	120 × 29
12	60	95 × 18	110 × 22	130 × 31
13	65	100 × 18	120 × 23	140 × 33
14	70	110 × 20	125 × 24	150 × 35
15	75	115 × 20	130 × 25	160 × 37
16	80	125 × 22	140 × 26	170 × 39
17	85	130 × 22	150 × 28	180 × 41
18	90	140 × 24	160 × 30	190 × 43
19	95	145 × 24	170 × 32	200 × 45
20	100	150 × 24	180 × 34	215 × 47

Small bearing	d	D × B
623	3	10 × 4
625	5	16 × 5
626	6	19 × 6
607	7	19 × 6
627	7	22 × 7
608	8	22 × 7
609	9	24 × 7
629	9	26 × 8

d over – incl.	C2, µm	CN, µm	C3, µm	C4, µm	C5, µm
6 – 10	0 – 7	2 – 13	8 – 23	14 – 29	20 – 37
10 – 18	0 – 9	3 – 18	11 – 25	18 – 33	25 – 45
18 – 24	0 – 10	5 – 20	13 – 28	20 – 36	28 – 48
24 – 30	1 – 11	5 – 20	13 – 28	23 – 41	30 – 53
30 – 40	1 – 11	6 – 20	15 – 33	28 – 46	40 – 64
40 – 50	1 – 11	6 – 23	18 – 36	30 – 51	45 – 73
50 – 65	1 – 15	8 – 28	23 – 43	38 – 61	55 – 90
65 – 80	1 – 15	10 – 30	25 – 51	46 – 71	65 – 105
80 – 100	1 – 18	12 – 36	30 – 58	53 – 84	75 – 120
100 – 120	2 – 20	15 – 41	36 – 66	61 – 97	90 – 140

Why does the same bore come in so many sizes?

The last two digits give the bore; the digits before them give the type and the dimension series, which sets the outside diameter and width for that bore. A 6005, a 6205 and a 6305 all fit a 25 mm shaft, but each is larger and carries more load than the one before (SKF rates them C = 11.9, 14.8 and 23.4 kN). The suffixes after the number are each maker’s own: 2RS1 is SKF’s contact seal, DDU is NSK’s and LLU is NTN’s. Read them in the catalogue of the maker named on the bearing.