Axial Load of a Standard Skate Ball Bearing

[Caito]

Hi!

I understand that standard 608 bearings as found in skates are "normal" radial bearings. However, there are also axial forces in a skate and they still work.

Does anyone have any data, datasheet, knowledge, etc., of how much axial force can one of this bearings take?


Thanks!!!

[ChrisDanger]

All ball bearings can handle some axial load. The ones below can only take load in one direction, but you can see how the cage can be made to fully enclose the balls and provide equal resistance in both directions.



Here's an SKF catalogue: www.skf.com/binary/77-121486/SKF-rollin ... alogue.pdf (22 MB)

A look at the bearing tables starting on page 322 gives static and dynamic radial load capacities, then page 316 shows how to calculate axial loads. Whatever bearing you want to buy, the manufacturer should provide similar details.

[tok-tokkie]

Boca Bearings used to have a technical article about skateboard bearings & other things but I don't see the link on their website now. Possibly contact them - they are helpful people. Here is their skateboard bearing listing https://www.bocabearings.com/parts/Skateboard-Bearings

[Greg Locock]

Ball bearings come in all sorts of configurations, as stated above, each with different axial load ratings. If you have vernier callipers you could work out whether it was deep groove, self aligning, etc etc from its dimensions. Or you could get an angle grinder and cut it in half. You'll learn more from that.

[Caito]

Thanks for the answers!

I'm talking about a standard 608 skate bearing. 22mm OD, 8mm ID. I think it's a "standard" deep groove bearing, i.e. not intended for axial force but still tolerates some.

Some images:




Cheers!

[Greg Locock]

A 608ZZ has a radial rating (Fr) of 1360 N, If you have an axial force (Fax) of half the radial force that then the effective static load is .56*Fr+1*.5*Fr, ie not much more than Fr - deep groove bearings actually like a bit of axial load.

So, if you can keep Fax to less than 800N then you are fine.

Bear in mind that defined Fr gives a fatigue life of about a bazillion revolutions, If you actually want to use a bearing for a particular purpose and life then bearing catalogs are immensely useful.

[ChrisDanger]

I think it's a "standard" deep groove bearing, i.e. not intended for axial force but still tolerates some.

From that catalogue I posted yesterday, the table shows that deep groove ball bearings can handle loads around 25-50% of the static radial load limit. The geometry of the groove very much determines this, and has been made "deep" especially to accommodate higher axial forces.