Angular contact bearings 7201-2RS

[Ketan SwaliParticipant @ketanswali79440]

Hi Michael,

Sorry for delay in reply. Just finished with visitors.

B = 40 Degree contact angle.

C = 15 Degree contact angle.

A = 30 Degree contact angle.

Above are usual specifications for A, B and C suffix on angular contact ball bearings. There are other contact angles once you start going into certain super precision match pairs depending on manufacturer, but generally, above is the norm.

See below the picture of what we have in stock. It looks like Pauls picture. It is 7206 B 2RS, so contact angle is 40 Degree. Easy to figure out which way is which:

If you want to open yours to check, you will need to use a very thin flat screw driver and wedge it in carefully in between the inner ring and the seal lip to 'pop it off', to ensure least damage.

Ketan at ARC.

Edited By Ketan Swali on 18/06/2015 11:34:12

[Neil WyattModerator @neilwyatt]

Of course there is another way…

If you press the inside into the outside, from the 'correct' diirection the bearing should get slightly 'thinner' than if you apply force the 'wrong' way.

Neil

[Ketan SwaliParticipant @ketanswali79440]

As a general guide for angular contact ball bearings, have a look at the link below.

As a general idea/guide to meanings of suffixes, read page 504 in the link.:

**LINK**

Although the bearings we sell are not made by SKF, most bearing manufacturers and traders use SKF referancing system for bearing designations, with small variances.

Ketan at ARC.

[John Stevenson 1Participant @johnstevenson1]

Personally I'd pop the seals off and have a look as these look nothing like any angular contacts I have fitted.

I wouldn't be surprised to find they are just deep groove bearings wrongly marked.

[Ketan SwaliParticipant @ketanswali79440]

Uhhhh probability of Michaels bearings being just deep groove bearings are low. Dont scare him

Poping off a seal may reveal a slight difference in the internal design to accomodate the seals they have used.

Ketan at ARC.

[Ketan SwaliParticipant @ketanswali79440]

Posted by Michael Horner on 17/06/2015 21:24:03:

If it works I might try it as a milling spindle for engraving type work. The bearings are rated to 20000 rpm.

Cheers Michael

If the bearings you have are 'B' = 40 Degree contact angle, with grease lubrication – which probably they are because of rubber seals (RS), the limiting speed rating with this specification is around 17,000 rpm as a single, or 15,000 rpm as a duplex (face to face or back to back). If you remove the seals, remove the grease and oil them, then the limiting speed 24000 rpm as a single, or 20,000 rpm as a duplex arrangement.

If you were using contact angles A or C, you would get higher speeds, but not easy to find them with rubber seals.

Ketan at ARC.

[IanTParticipant @iant]

Useful stuff to know – thank you Ketan

IanT

[Ketan SwaliParticipant @ketanswali79440]

Extract from NACHI catalogue for suffix A, B, C:

Limiiting speed from NACHI catalogue, for 7201 A, B, C 'open' type, to be used as 'general guidance' only. 2RS reduces limiting speeds due to the friction of the lip of the seals against the inner ring, but still, you get the general idea:

Ketan at ARC.

Edited By Ketan Swali on 18/06/2015 18:15:30

[Ketan SwaliParticipant @ketanswali79440]

Posted by Ketan Swali on 18/06/2015 11:32:30:

See below the picture of what we have in stock. It looks like Pauls picture. It is 7206 B 2RS, so contact angle is 40 Degree. Easy to figure out which way is which:

Small correction, the above picture is for 7201 B 2RS, and not 7206 B 2RS. …. Sorry.

Ketan at ARC.

[Michael HornerParticipant @michaelhorner54327]

Thanks for all the input.

Simply Bearings have not been in touch so I think I will send them an email perhaps refer them to this thread!

I don't fancy popping a seal off because if they are labled wrong I am stuck with them.

If they reply I will let you know what they say.

Cheers Michael.

[duncan webster 1Participant @duncanwebster1]

If you look at http://medias.schaeffler.com/medias/en!hp.ec.br.pr/72..-B-2RS*7201-B-2RS-TVP you will see the dimensions they should be. The outer ring look like more of a giveaway

[Bob Brown 1Participant @bobbrown1]

Why not just send them back an purchase something that is easier to identify?

Simply bearings offer

No Quibble 100% refund guarantee

We offer a 100% no quibble satisfaction guaranteed refund policy!

If you are not 100% happy with the quality or any other aspect of the goods we have supplied then please return them and we will be only too happy to refund you.

We are happy to accept returned goods within 90 days of purchase.

On a personal note, do not like cheap bearings as their quality can be a little suspect.

Bob

[Nitai LeviParticipant @nitailevi73768]

A bit late but FWIW…

Is there a letter after the 7201 number on the bearing? As others mentioned, that would indicate the angle. B is 40 degrees and that is usually very easy to see. I'm guessing yours is C which is 15 degrees so hard to tell.

If you measure the entire outside diameter of the inside race or the inside diameter of the outer race it might be easier to tell since you'd get double the difference than measuring the thickness of the race.

Every angular contact bearing I've seen had the thinner inner race on the ID side. Of course that doesn't mean it's always the same and I've never had Chinese angular contact bearings.

Although with a shallower angle it might be more tricky, but you can lightly press the inner race against the outer race to both sides and compare. On regular ball bearings the play is pretty even overall. On B angular contact bearings the difference is very obvious and you can't really pres the inner race much at all to one of the sides. With a shallower angle the difference might be smaller but tehre's a chance you could feel it. The side you press toward with less play would be the direction of the bearings facing each other to creat thrust (sorry about the clumsy explanation, it's not my first language).

I guess you probably solved the problem by now

[AjohnwParticipant @ajohnw51620]

Loosely related – Does anyone know what the effective contact angle of magneto bearings usually is?

John

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[Michael HornerParticipant @michaelhorner54327]

Hi

Below is the reply from simply bearings.

Hello Michael

Thank you for your enquiry. I have checked the remainder of the 7201 bearings as ordered and the direction of thrust is against the non printed side. The axial load is to be presented to the non printed side. I hope this makes sense, these small ones often bring up this question, as they are generally too small to feature any visible physical difference in the races which is commonly found.

If you require further assistance then please do not hesitate to contact me as I will be more than happy to help.

Best Regards

Your Simply Bearings Help Centre Team

[MuzzerParticipant @muzzer]

Couldn't be more ambiguous – depends where you are standing! Surely the printed face is to be loaded under compression. I'm sure he knew what he meant and I think we know the correct answer.

He assumes the load is what is presented to the inner race.

If you insist on asking you will get some form of answer….

Edited By Muzzer on 13/07/2015 20:23:18

[Nitai LeviParticipant @nitailevi73768]

Posted by Michael Horner on 13/07/2015 19:45:04:

…….and the direction of thrust is against the non printed side. The axial load is to be presented to the non printed side.

It's not completely clear but I think it means the same as what I found on angular contact bearings before i.e. the printed side is where the inner race is thinner and outer race is thicker.

[Colin LLoydParticipant @colinlloyd53450]

A related question on Angular bearings: While replacing the damaged nylon gear wheels within the headstock of my Amadeal CJ18A lathe (similar to C3), I decided to change the spindle bearings for Angular ones – 7206 B 2RS from Arceurotrade. The discussion above and the excellent Arceurotrade visual guide to installing these angular bearings helped a lot – except in my enthusiasm I forgot to put the plastic bearing cover at the Mandrel end before putting the Angular bearing on. If I had known what was to happen next – I might have cut the plastic cove in half and then glued it back together around the spindle. Using normal gear removal tools that fits to the outer ring of the bearing caused the inner ring to remain on the spindle shaft while the rest of it came away – easy to see why as that is how they are probably put together (and also how I pressed the bearing back together – although I won't use it and have bought another one). As the bearing is installed hard up against the mandrel shoulder – there is no easy way to get access to, and purchase on, the inner ring of the bearing.

So the question is – how would more experienced engineers than me go about removing these angular bearings, in this situation, without breaking them. – in case I need to do it again.

[Nick HughesParticipant @nickhughes97026]

Hi Colin,

Use this type of puller

Nick.

[Colin LLoydParticipant @colinlloyd53450]

Hi Nick,

Thanks for the reply – but the photo doesn't really show me how this would work. To explain further I've attached part of a diagram from the Arceurotrade guide to replacing angular bearings on their C3 lathe. It shows the Mandrel end of the headstock with the angular bearing in place on the spindle. Imagine the headstock casing removed and you have my problem. Using a normal gear puller on the outer race ring of the bearing causes the outer ring and ball race to become separated from the inner race tight on the spindle. This happens because of the way that angular bearing are made and the recommended facing of the bearing on the spindle. I suspect if the bearing was the other way round – pulling on the outer race would work. As you can see, with the bearing hard up against the Mandrel shoulder – there is no gap to get anything of significant leverage onto the inner race to effect removal.

[Nick HughesParticipant @nickhughes97026]

Hi Colin,

This video shows how they work.

 

If you needed to use the puller on an intact bearing, then it would probably require extra clearance machining in it, to clear the outer race.

 

Nick.

Edited By Nick Hughes on 07/09/2017 15:01:32

[Colin LLoydParticipant @colinlloyd53450]

Hi Nick,

Yes – the question was how to remove one of these angular bearings without breaking it. I have just bought one of those gear puller kits as shown in the Video – it was also what Neil Wyatt suggested (in a private email) – but it didn't arrive until after I'd used a Draper 2-legged puller to try to get it off. Once the outer ring and ball race is removed – it's quite easy to get the inner race off. I do note that the 2 clamps supplied with the kit have a chamfered front edge which fits around the bearing. It might be possible, by reversing the clamps so that the indented side faces the mandrel shoulder rather than facing the bearing, to tighten the clamps so that the horizontal tightening produces sufficient upward movement of the bearing to then reverse the clamps to their normal operation and use in the normal way – the clamp shoulder will then sit on the inner ring rather than the outer ring. I don't particularly want to try this as I don't want to break another bearing – although Arceurotrade would appreciate another bearing sale – but it might be worth a try if I really need to get the bearing off in the future.

[Clive FosterParticipant @clivefoster55965]

Realistically, for anything other than the most non critical applications, you are best off considering any bearing needing to be removed by significant force as scrap. Firm push within hand force levels, even if a tool is needed to get at things, is about my safe limit. If its in an alloy casing, minor heating to boiling water temperature or so to help release it is fine. When I was playing around with old British motorcycles I used to set the casing up open end down and warm things up until the bearing dropped out of its own accord.

Sometimes no option but to re-use for now whilst a new one is sourced. But bearings are inevitably rather deep inside so, unless its something as simple as an electric motor, temporary re-use wastes a lot of time buttoning up and unbuttoning again.

Its rare to find anything using angular contact bearings with provision for safe extraction. I have run into something with taper roller bearings that had holes drilled in the back of the outer race mount so it could be extracted. Big bearing, 4 or 5 inches diameter as I recall and very not cheap. The race was lunched so I got very careful with a pin punch. Probably proper puller for professionals with push pins aligning with the holes and something in the middle to ensure a straight pull.

Clive.

[Colin LLoydParticipant @colinlloyd53450]

Thanks Clive,

Probably what I needed to know. With little experience of bearings and how to remove them, I just needed to know if there was a method out there that I was unaware of. Your post more or less tells me there isn't and also importantly to regard any removed bearing as possibly scrap unless the removal force is located close to the binding junction – in my case between the spindle and the inner ring of the bearing.

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