# Bearing failure rating? Simple rev counter?

1. Nov 5, 2005

### agusta

Firstly I would like to point out I have absolutely no idea what im doing and will most likely be blind or dead by tomorrow. But anyway.

I've finally finished me first turbo jet engine (from scratch I would like to add and designed myself and dodgy as I am pretty convinced that it wont explode (mainly because its about a hundred times stronger than it needs to be) but I do expect it to either disintegrate or have bearings fail. I have used roller bearings, which was a stupid idea I know but it saved me a lot of time. What I would like to know is how I can determine roughly what speed a roller bearing will fail at excluding sideways force and heat etc. I have a formula for the failure rating when a certain sized bearing is under a sideways force but I cant find one for the maximum revs they can handle.

There must be a formula where you can use the ball size, number of balls, outside diameter, inside diameter width etc.

Also I would like to have a simple way of working out the number of revs its doing. Maybe using a strobe light and adjusting the frequency until the impeller stops moving? Then you could use that frequency someway. Just a thought. (probably stupid but hay im at high school where making a fire poker in engineering is classed as complicated)

The thing is I don’t what it disintegrating and blinding a few fellow class mate. I suppose I would get on the news if it exploded and kill a few people (I shouldn’t say that, sorry)

I know im only at high school and you guys are all probably either 4th year mechanical engineering students or actual engineers but I hope to be a 4th year mechanical engineering student one day so give use a break)

So if you have any ideas that’d be great. Anything really.

I posted this in general engineering but i though it would be more appropriate here.

Cheers

Last edited: Nov 5, 2005
2. Nov 5, 2005

### faust9

Bearings have data sheets. The max RPM, load limits and expected failure life are quoted in said data sheets.

3. Nov 5, 2005

### FredGarvin

See my response in the General Engineeering Topic. Please don't double post.