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Combination bearing torque

teachme

Aluminum
Joined
Apr 13, 2020
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.
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ViktorS

Aluminum
Joined
Apr 26, 2021
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.
 

johansen

Stainless
Joined
Aug 16, 2014
Location
bainbridge island
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.
 

john.k

Diamond
Joined
Dec 21, 2012
Location
Brisbane Qld Australia
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

Aluminum
Joined
Apr 26, 2021
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.
 








 
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