Hey guys, working out of town and need a quick bearing cross reference: 75BC03. This is on a 700 hp IR Centac air compressor, motor drive end bearing. Would appreciate your help.

75BC03 = 6315

I bet you probably already knew that. I don't know the fault frequencies and could depend on bearing manufacturer which I also don't know. (I pick SFK if I don't know the manufacturer).

This is what I found for an SKF 6315.

6315.pdf (9 Kb, 86 downloads)

Patrick,

I believe that the informations in your pdf file are wrong for a SKF 6315.

Here are the numbers from the SKF site:

SKF 6315
Pitch diameter 4.6259 in.
Rolling element diameter 1.0625 in.
Number of rolling elements 8.

Shaft speed frequency 1.00 Hz
Inner race defect frequency (BPFI) 4.92 Hz
Outer race defect frequency (BPFO) 3.08 Hz
Cage defect frequency (FTF) 0.39 Hz
Ball spin frequency (BSF) 2.06 Hz
Rolling element defect frequency 4.12 Hz

Thanks guys. Is there an online reference that tells how to cross these numbers? I have the CSI database, but it uses the 6315-type numbers.

Here is a file someone posted once on the old board.

In the example above there are 3 pieces of info conveyed by each part number
1 - it is a standard ball bearing ("deep groove" - "Conrad")
2 - Bore is 75 mm
3 - Dimension series 03 (the other choice is 02)

For the AFBMA 75BC03, 75 stands for bore dimension in mm, BC stands for "Ball, Conrad" and 03 stands for dimension series 3

For the p/n 6315, 6 always means Conrad ball bearing, 3 means dimension series 03, and the last two digits 15 are the bore in mm divided by 5. ie 75/5-=15

AFBMAtoSKF_PN_ConversionIncludingSuffix.doc (28 Kb, 165 downloads)

This is a short cross-reference of bearings most commonly found in electric motors:

"AFBMA"- "Regular"
Designation Designation

Deep groove ball bearings:

15BC02- 6202
17BC02- 6203
20BC02- 6204
25BC02- 6205
30BC02- 6206
35BC02- 6207
40BC02- 6208
45BC02- 6209
50BC02- 6210
55BC02- 6211
60BC02- 6212

25BC03- 6305
30BC03- 6306
35BC03- 6307
40BC03- 6308
45BC03- 6309
50BC03- 6310
55BC03- 6311
60BC03- 6312
65BC03- 6313
70BC03- 6314
75BC03- 6315
80BC03- 6316
85BC03- 6317
90BC03- 6318
95BC03- 6319
100BC03- 6320

Cylindrical roller bearings:

100RN/RU02- N/NU220
105RN/RU02- N/NU221
110RN/RU02- N/NU222
80RN/RU03- N/NU316
85RN/RU03- N/NU317
90RN/RU03- N/NU318
95RN/RU03- N/NU319
100RN/RU03- N/NU320

Angular contact ball bearings :

25BT03- 7305
30BT03- 7306
35BT03- 7307
40BT03- 7308
45BT03- 7309
50BT03- 7310
55BT03- 7311
60BT03- 7312
65BT03- 7313
70BT03- 7314
75BT03- 7315
80BT03- 7316
85BT03- 7317
90BT03- 7318
95BT03- 7319
100BT03- 7320

This message has been edited. Last edited by: Alec,

I guess I should have mentionend - for bearings smaller than 20mm bore (~0.8"), the "bore-divided-by-5" rule doesn't work for finding last two digits (the XX in 63XX or 62XX).

For smaller bores (below 20 mm) use:

00: 10 mm
01: 12 mm
02: 15 mm
03: 17 mm

This message has been edited. Last edited by: Alec,

Not sure why mine was wrong, but I did notice my CSI bearing ID for an SKF 6315 is 188 and Rusty's is 190. Difference of versions? I'm using 4.81, 7/15/04.

Patrick,

The specs of your bearing are for a SKF 6003.

This message has been edited. Last edited by: Alec,

Alec,

Thank you! I have always been just calculating them out over the years, as needed. You have given us all a very useful "cheat sheet". Excellent contribution to this forum!

Thank You!

You're welcome Chris!

Try to bring my very small contribution to this great and interesting forum!

If you call SKF they will sned you and AFBMA conversion booklet.

Call 215-513-4400 ask for Marina. She will send you out the booklet. It is a huge help for me when building data bases from name plate info.

Kelly

You guys should all be referencing The Bearing Expert Interchange and Vibration database at http://www.sourceindex.com click DEMO for free reports. With one part number or dimension, you will get your frequency reports, interchange reports, harmonics, variable contact angle reports and more. AFBMA part numbers are included on all reports.

quote:

For the p/n 6315, 6 always means Conrad ball bearing, 3 means dimension series 03, and the last two digits 15 are the bore in mm divided by 5. ie 75/5-=15

Here's something from Pete's post as a quote from someone else - I see a flaw in the quote and hope it isn't confusing:

6 315 the 3 part is duty number as 4 is heavy duty and 2 light duty and 1 is ultra-light as I recall. and extension of 03 means extra clerance while 02 is less and then theres's a whole series of questions regarding the ABEC#.
so, 6 (conrad) 3 (medium duty) 15 (times 5 - bore dia in mm).

Just in case someone else took a double-take and maybe a little slow like me.

Hey Sam. I think the word document attached above explains it pretty well.

The 3 is 6313 is called a dimension series and it can have several values 0,2,3,4 as you mention but I'm pretty sure 2 or 3 is all you will ever see for ball bearings.

The extensions or suffixes you mention are clearly spelled out in the attached document. They do not affect fault frequencies so they may not be important for vib analysts. But I agree they are important - especially if you are going to order a bearing.

I'm not sure what you meant by flaw. As far as I know the part of my message you quoted was correct. But if I'm wrong let me know (it wouldn't be the first time).

Alec's bearing list above gave me an idea. For you CSI users, why not include this list in your 'note codes'... would make it much easier to note the bearing number when you find a suspect bearing.