Combination bearing torque

[teachme]

Can you easily spin a 1" OD combination tapered bearing by hand, with 200 lbs of thrust force on the bearing? The thrust is rated for 900 lbs.
The bearing fixture will be compressed against a paper roll (50 lbs), and the paper has to roll off without ripping (with starting torque).
Just need a general idea. The thrust force can be lowered.

 

[john.k]

Yes,the setup is similar to a wheel bearing on a motorbike front wheel ...spins easily ,right?

 

[ViktorS]

It will probably work just fine, depending on a lot of different factors such as how you grab the paper to pull it from the roll etc.

But in generat a ball bearing will have less stiction and somewhat less running friction, so an angular contact bearing might be better if you are worried.
They are usually more expensive though.

 

[magneticanomaly]

IIRC rule of thumb coeficient for ball bearing friction s .0001, for roller bearings .0003 that may get you in the ballpark

 

[johansen]

Skfbearingselect is an online calculator that will calculate static and rolling friction for thier bearings.

I plugged in 1 KN thrust on a 25.4mm ID 62mm outer diameter bearing at 20 rpm and got 214Nmm static torque with .39 watts lost at 20rpm.

 

[mhajicek]

Doing a heavy duty toilet paper dispenser? Make it ratchet so it can't be run backwards!

 

[john.k]

The whole design is hopelessly over specced....taper rollers are quite expensive,one $2 deep groove ball would be quite OK either end.........must be a school asignment .

 

[ViktorS]

I'm not sure I really agree.
A tapered roller bearing is, strangely, quite cheap. Especially if one considers the force they can withstand. A 5-10$ 30203 or 30205 is set-and-forget, one "never" have to worry about overloading them.

For example, look up the closest deep groove that can handle the same static and dynamic load as a 30205. List price for us is about 7,50$ (for me).

A 6005 groove bearing can handle about 1/3rd of the dynamic and 1/5th of the static load of 30205. That bearing is 7.35$ in list price for me.

Disclaimer: I have not looked up axial/radial load cases, but the difference will be even more there. A deep groove have their applications but this is to me atleast a clear case when tapered roller reign supreme.