F1 in schools bearings

[dan217]

Hello guys so I am new to F1 technical so if I make a mistake please forgive me.

I am taking part in the F1 in schools project and I took part last year as a rookie team this time we really want to win it and are starting to work early and will use the summer vacation to be better equipped.

We used fully ceramic ball bearings but unfortunately they were broken when we raced them the balls fell out in a few of them and in one of them the outer ring was broken. Does that happen often as the bearings were working fine when we sent them to be inspected. So we are looking into other types of bearings like roller bearings as they're more stable.

So which bearings will have lower coefficient fully ceramic radial ball bearings or roller bearings or sapphire jewel bearings?Or perhaps if you have any other suggestion. Other aerodynamic aspects of the car are going very well we are just having trouble over which bearings to use. All responses are greatly appreciated.

[tok-tokkie]

I don't know where you got your bearings. Boca in the US have been used by several successful past competitors.

Mounting the bearing in the wheel with the axle fixed in the body makes the balls run much faster compared to bearing in the body with rotating axle. 1 rev of the wheel makes the balls travel much further if the outer race turns as against the inner race. In your application you are looking for minute reductions in resistance.

[dan217]

I don't know where you got your bearings. Boca in the US have been used by several successful past competitors.

Mounting the bearing in the wheel with the axle fixed in the body makes the balls run much faster compared to bearing in the body with rotating axle. 1 rev of the wheel makes the balls travel much further if the outer race turns as against the inner race. In your application you are looking for minute reductions in resistance.

your response is much appreciated but we did buy those bearings from boca and fitted them in our wheels after experimenting with fitting them inside the body. So does anyone know where we can get ceramic roller bearings? Also what is the difference between needle bearings and roller bearings as the pictures look the same. So roller bearings or ball bearings we know theyre both quite good but which would be beter for our application as we dont have the money to buy ceramic variants in both the roller type and the ball type.

[rjsa]

I don't know where you got your bearings. Boca in the US have been used by several successful past competitors.

Mounting the bearing in the wheel with the axle fixed in the body makes the balls run much faster compared to bearing in the body with rotating axle. 1 rev of the wheel makes the balls travel much further if the outer race turns as against the inner race. In your application you are looking for minute reductions in resistance.

I'm sorry but I'll have to disagree. Mounting bearings in the wheel will subject the bearings to bigger torsional loads, but will have absolute no effect on rotation speed, only direction.

EDIT: BTW, that torison most likelly killed those bearings. I guess (don't take my word on it) needle bearings would do a better job if mounten on wheels, their geometry should be less sensitive to torsion. You also should position the bearing centered to the wheel's contact patch.

[rjsa]

OK, seems I was wrong about the needle berings and the torsion loads. Angular contact path ball bearings or double rowed ones would be the choice.

See SKF's selection matrix:

[dan217]

I don't know where you got your bearings. Boca in the US have been used by several successful past competitors.

Mounting the bearing in the wheel with the axle fixed in the body makes the balls run much faster compared to bearing in the body with rotating axle. 1 rev of the wheel makes the balls travel much further if the outer race turns as against the inner race. In your application you are looking for minute reductions in resistance.

I'm sorry but I'll have to disagree. Mounting bearings in the wheel will subject the bearings to bigger torsional loads, but will have absolute no effect on rotation speed, only direction.

EDIT: BTW, that torison most likelly killed those bearings. I guess (don't take my word on it) needle bearings would do a better job if mounten on wheels, their geometry should be less sensitive to torsion. You also should position the bearing centered to the wheel's contact patch.

Well they did have an effect on rotation speed, when placed in the body because when thye're placed in the body the axles spin rather than the wheel this means the inner ring spins raher than the outer ring and it's not meant to spin as fast as the outer ring thats why the bearings had to be placed in the wheels as we have realised after experimenting.

[dan217]

OK, seems I was wrong about the needle berings and the torsion loads. Angular contact path ball bearings or double rowed ones would be the choice.

See SKF's selection matrix:

First of all thanks for taking the time to respond and help us out. So are you suggesting that double rowed ball bearings are the best for us? I cant see the text in the picture due to the low resolution. Thanks

[xpensive]

O-mounted angular contact ball bearings would probably be the way to go friction-wise;
http://www.skf.com/portal/skf/home/prod ... link=1_3_1

You can make your own calculations here;
http://www.skf.com/portal/skf/home/prod ... nk=1_0_37a

I prefer FAG myself, much better service, but SKFs catalogue is easier to read.

[tok-tokkie]

I don't know where you got your bearings. Boca in the US have been used by several successful past competitors.

Mounting the bearing in the wheel with the axle fixed in the body makes the balls run much faster compared to bearing in the body with rotating axle. 1 rev of the wheel makes the balls travel much further if the outer race turns as against the inner race. In your application you are looking for minute reductions in resistance.

I'm sorry but I'll have to disagree. Mounting bearings in the wheel will subject the bearings to bigger torsional loads, but will have absolute no effect on rotation speed, only direction.

EDIT: BTW, that torison most likelly killed those bearings. I guess (don't take my word on it) needle bearings would do a better job if mounten on wheels, their geometry should be less sensitive to torsion. You also should position the bearing centered to the wheel's contact patch.

I said the balls would travel much further (& therefore faster). The circumferece of the outer race is much greater than the circumference of the inner race so when the wheel does 1 rev the balls roll much further if it is the outer race rotating compared to if it is the inner race.

These minature bearings are only available as regular deep groove bearings - no angular contact bearings available as far as I know.

Needle roller bearings have higher frictional resistance than ball bearings plus they require additional bearings to locate the shaft in the sideways direction.

[xpensive]

...
I said the balls would travel much further (& therefore faster). The circumferece of the outer race is much greater than the circumference of the inner race so when the wheel does 1 rev the balls roll much further if it is the outer race rotating compared to if it is the inner race.
...

Eeh...don't you think it's the relative rpm between inner and outer race that decides the balls' travelling speed?

...
These minature bearings are only available as regular deep groove bearings - no angular contact bearings available as far as I know.
...

Try this; http://www.grw.de/uploads/media/GRW_pro ... alogue.pdf

[dan217]

Guys I appreciate the responses so much and right now im doing my research on these angular contact bearings. you guys really are the nicest people ever.

[tok-tokkie]

...
I said the balls would travel much further (& therefore faster). The circumferece of the outer race is much greater than the circumference of the inner race so when the wheel does 1 rev the balls roll much further if it is the outer race rotating compared to if it is the inner race.
...

Eeh...don't you think it's the relative rpm between inner and outer race that decides the balls' travelling speed?

...
These minature bearings are only available as regular deep groove bearings - no angular contact bearings available as far as I know.
...

Try this; http://www.grw.de/uploads/media/GRW_pro ... alogue.pdf

1 rev of the outer race sends the balls much further than 1 rev of the inner race. The relative speed of the races is also proportional to that (when the wheel is doing a certain rpm then the relative speed is much greater if the outer race is rotating). The balls travelling speed is, of course, determined by the relative speed between the two races. In most cases 1 race is stationary, if it is the inner race then, for the same relative rpm the balls are travrelling much faster than when the outer race is rotating.

The GRW bearings I did not know about. The deep groove bearings start at 1mm bore but the angular contact bearings start at 3mm bore. Steel races with steel of ceramic balls available. I expect they are using 2mm bore bearings.

[rjsa]

...
I said the balls would travel much further (& therefore faster). The circumferece of the outer race is much greater than the circumference of the inner race so when the wheel does 1 rev the balls roll much further if it is the outer race rotating compared to if it is the inner race.
...

Eeh...don't you think it's the relative rpm between inner and outer race that decides the balls' travelling speed?

...
These minature bearings are only available as regular deep groove bearings - no angular contact bearings available as far as I know.
...

Try this; http://www.grw.de/uploads/media/GRW_pro ... alogue.pdf

1 rev of the outer race sends the balls much further than 1 rev of the inner race. The relative speed of the races is also proportional to that (when the wheel is doing the same rpm). The balls travelling speed is, of course, determined by the relative speed between the two races. In most cases 1 race is stationary, if it is the inner race then, for the same relative rpm the balls are travrelling much faster than when the outer race is stationary.

The GRW bearings I did not know about. The deep groove bearings start at 1mm bore but the angular contact bearings start at 3mm bore. Steel races with steel of ceramic balls available. I expect they are using 2mm bore bearings.

No matter where you hook the bearing the distance travelled by the car is the same. Since the wheel has a fixed diameter, the number of turns will be also the same. So will be the number of turns of the inner bearing ring relative to the outer, no matter which is parked and which is running. Please take a minute and think this thru. You will regret haven't done it earlier.

[xpensive]

...
The GRW bearings I did not know about. The deep groove bearings start at 1mm bore but the angular contact bearings start at 3mm bore. Steel races with steel of ceramic balls available. I expect they are using 2mm bore bearings.

GRW is kinda xpensive top of the line miniatures, but if it's 2 mm bore I would probably go for regular ball bearings mounted back-to-back in an O-configuration. There are applications and how to calculate in the catalogue conveyed, page 63.

[tok-tokkie]

No matter where you hook the bearing the distance travelled by the car is the same. Since the wheel has a fixed diameter, the number of turns will be also the same. So will be the number of turns of the inner bearing ring relative to the outer, no matter which is parked and which is running. Please take a minute and think this thru. You will regret haven't done it earlier.

Hopefully you will regret what you posted:
On a F1 in Schools track of 20m with 30mm diam wheels the wheels turn 212 as the car traverses the track.

Typically they have 2mm axles with a 6x2 bearing:


d1 = 2mm d2=6mm ball = 0.8mm ID of outer race = 4.8mm OD of inner race = 3.2mm

Let us approximate what happens by assuming that the balls roll without slipping on both the inner and outer races.

If the bearing is mounted in the wheel and the axle is rigid in the body the then each rev of the bearing outer shell will drive the balls π*4.8 = 15mm

If the wheel is rigidly mounted on the axle which turns the inner race of the bearing which is mounted in the body the balls will be driven π*3.2 = 10mm

The balls run 50% further when the outer race rotates.

If the balls don’t slip then in the first case each ball will have run 15 mm along the inner race taking it 1.5 revs. In the second case the balls run 10mm along the inside of the outer race taking them just 240 degrees.