Uni work - Brake assembly done

[axsaxoman]

I take it you have gone 2 bearings rather than a single pre spaced unit for weight saving,

[adamskiTNR]

I could probably have made a lighter overall design by using a smaller, wider single bearing. But the main concept of the upright is that it can be used on both the right and left hand side without needing any design changes to save on manufacturing costs and time. This requires such a bearing design. The 2 bearing setup is also much nicer to assemble and take apart.

[axsaxoman]

no reason why it still couldn,t be suitable forall 4 corners --circlips in both sides and a good press fit (warm up housing to fit bearing) --it ain,t going anywhere if you use brg fit as well

[adamskiTNR]

I'm not a huge fan of press fits, especially into aluminium. I like to be able to assemble and disassemble race car parts without feeling like i'm fatiguing and wearing the parts in the process. And like this you can take it apart at the event if need be, without the need for a press. And adding a circlip on both sides will require the bearing to be set further into the upright and so increase the moment created by tyre side loads.

[adamskiTNR]

Better shot of the angular contact bearings.

[Tom5190]

looks good matey, is this for your diss?

[adamskiTNR]

No, just my second year project. did the upright in my first year. I'm thinking about doing something more ground breaking for my dissertation, maybe integration of electric drivetrains, not sure yet

[adamskiTNR]

Cut away picture of the (provisonally) completed design.
The blue element is a stand in component for the centre of the wheel.

[axsaxoman]

Originally Posted by adamskiTNR

I'm not a huge fan of press fits, especially into aluminium. I like to be able to assemble and disassemble race car parts without feeling like i'm fatiguing and wearing the parts in the process. And like this you can take it apart at the event if need be, without the need for a press. And adding a circlip on both sides will require the bearing to be set further into the upright and so increase the moment created by tyre side loads.

even with your 2 bearings you still need an interference fit for casings .
and if you make internal hub the size correctly warming uprgiht to 130c max will make the bearing a slide fit ,or just a light press fit which will not damge the upright . or even put bearing in freezer before fitting .
a 1or 2thou interfernece fit is all that is needed ,even looser if you use modern brg fit adhesive
it is a very common way of assembly for close fitting parts
tthe extra "moment" will be very small and the life of a correct preloaded bearing will be a long time in racing terms ,certaintly alot more than a single race season .
far more likely to have a corner knocked off the car than having to change a bearing and being able to use it on all corners must make spares holding +manufacture cheaper .I would have thought that thinking that way would win you "brownie" ponits as well for simplicity

[adamskiTNR]

The bearing and hub, as well as bearing to upright are both close interference fits. (I cant remember the engineering jargon code for the tolerance).
Yeah I've used 4 cans of aerosols in a 24hr race to cool a bearing down for fitting lol.

[adamskiTNR]

Really expensive bearings are nice to work around though. As these bearings are toleranced to microns. So the tolerance of the fitting component is all you need to worry about in the design.

[axsaxoman]

not sure how you go about working out the differential expansion rates of the alloy uprught to the 2 indivual brgs and the alloy inbetween them --,never mind the through bolt that keeps the load on them .
a single double row brg with intergral preload spacer must be be far more dimensional stable --maybe that why in your 24hr race bearings failed --preload changed .
you don,t need to know accuratly the preload to tighten the through bolt to with double row --as its not so critical to get the preload on the bolt correct --just up tight and spacer in brg wil give you correct preload

[adamskiTNR]

The 24hr bearing was a full ceramic porsche 911 rsr single wheel bearing.
And yes that's the idea. The preload spacer being exactly that. the width of it being the variable for bearing preload.
And the expansion is a tricky component of this design. As you can see in the images the material around the bearing carrier seems very thick. It is indeed thicker than it needs to be for structural reasons. The idea being that the exterior of the upright is cooler than the material around the bearing. This "should" force the thermal expansion to contract around the bearing than the entire upright "scaling" outwards, if that makes any sense. As you can imagine this is where race teams with lots of money and resources can shave weight off while keeping the thermal expansion under control. I just dont have the time to run that many simulations.

[axsaxoman]

I could be wrong --but my guess would be that most of the heat comes from the brakes etc ,into the flange then into the hub .and not from the brg outwards.

single seater has no mudgaurds or wheel archs like the porsche or the weight ,so heat build up should a lot less from brakes etc than a "tin top" with a rear engine turbo lump .
I would imagine that the alloy upright will expand alot more than the bearing and would expect the brg too become loose -er in its fit ,not tighter if anything as the steel brg will not expand as much as the upright ,which is why you make it an interference fit to start with
as i see it in your design doesnot have a factory made preload spacer.
So your single bolt +its torque setting is what will be very critical to the preload it gets when at running temp ,then add the expansion of the hub to complicate things
--where as with a preloaded single cased double row brg ,the preload variable is not there to the same extent as all the components are of basically same material in the brg .

very interesting anyway

and I am not attmpting to make derogaotry comments on your design --not in anyway --just different ways of looking at things

[adamskiTNR]

Yes the majority of heat goes through the brakes, into the brake flange and then from there the route to the upright is through the rest of the hub, then the bearings, then the upright. I believe that this route will conduct more heat to the upright than radiant heat going straight to the upright from the disc. And as long as the outside of the upright remains cooler than the centre, the centre should expand fairly uniformly and not tend outwards away from the bearing.
I hat the number of variables in this design process lol.
In regards to preload:
The preload of the pair of bearings will be applied until the inner races compress against the preload spacer. At this point any more pressure will preload the bolt and not the bearing set. This preload of the bolt will then be affected in expansion, eventually getting to a point where the bearings will leave the face of the preload spacer. Which i hope wont happen.

[adamskiTNR]

Better view of the conical spline hub face. And i've done the FEA on it today and it's done pretty well i must say. Nothing exploded so success.

[adamskiTNR]

Final rendering of the full assembly. Now just to finish the write up -_-

[Aaron]

Awesome.

How many hours did that take on Solidworks?

[adamskiTNR]

Several......lol. i didn't really keep track, as it was done alongside lots of other work and along the research needed for each element of the design. But i reckon (with the upright done last year) around 15 hours, maybe 20 with the FEA. Hard to say as its not like you are doing it non stop drawing a cad model of an engineering drawing fort example. You think you draw, you assess, you edit, you draw more, you assess, you research, you delete, you re draw, etc etc.

[Tom5190]

Looks really good matey, got all my dissertation stuff finished and handed in now cant wait to finish!