Machining Tol. RE: Multi Piece wheels.

[littleoneder]

Hi. my name is Laurence.

For the longest time I have wanted to to make a three piece wheel of my own design.

I know about TRA yearbooks. I don't think I would try to market these wheels outside of NA. But living in Canada, does Transport Canada have the same requirements as the U.S.?

Also, I am trying to understand what kind of tolerances are given to the spider portion? I.e., tolerances of hub bores, outside diam (where the spider sits inside the barrel). And what kind of tolerances are typically held when rolling the barrels? What holds the spider central to the barrels? If there is tolerance in the bolt hole circle, and the actual size of the bolt hole, and the fit of the spider to the barrel, then you must mount everything using a fixture, no?

With the thicknesses of the arms of the spider, and where it mounts to the barrels, and even where it mounts to the hub, I would need some sort of an FEA done on the model right? To determine how much material needs to be in certain places?

I am thinking about purchasing the TRA Yearbook. Are there other pieces of literature I should pick up before I start cutting metal?

 

[GregLocock]

Every country I know of has the equivalent of T&RA. They also have specific wheel strength tests that are not covered by T&RA. For instance in Australia we have an exciting test where we blow the tire out at 100 kph and the rim must not fall apart. We also have pothole strength requirements. I think T&RA gives you enough tolerances to establish a machining scheme, how you handle assembly tolerances is a separate issue.

The SAE publishes some standards on fatigue life tests etc.







Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[CapriRacer]

TRA is important in that it will give you the dimensions and the tolerances of everything that is important in fitting a tire to a rim.

But what it does NOT do is tell you the allowable dimensional tolerance for things that are not part of the tire / rim interface. Things like runout, center bore dimensions and tolerances, bolt circle dimensions and tolerances, etc.

 

[littleoneder]

Thanks GregLocock, and CapriRacer.

I don't suppose you know of any more reference material that pertains to wheels, do you?

 

[GregLocock]

http://www.sae.org

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Xwheelguy]

littleoneder,

In addition to all of the above, T&RA publishes the yearbook as well as a general Engineering Design Guide, which I believe contains some general information regarding wheel design in it.

You'll need to know your brake clearance (a profile of the brake is helpful but not easy to manually obtain) which could somewhat affect the spoke thickness you mentioned. If making a custom wheel for a factory vehicle, I would recommend using an offset that is close to the same as the original wheel on the vehicle (± 5mm of the factory wheel offset).

Before performing any FEA, you had better make sure you know how to set up the simulation to perform similarly to the fatigue tests such as rotary fatigue (AKA dynamic cornering fatigue) and radial fatigue (AKA drum endurance). FEA results can be garbage if you don't have it set up correctly....and that type of information is not going to be easy to find, which is very typical for wheel and tire engineering information.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

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