wheel bearing play

[idontcare]

Hello everyone,

I have some doubts regarding double row bearings. i have found that to use double row bearings you need to provide a nut on the hub to give pre axial load otherwise there will be play in the bearing. So, next year I'm planning to go for single row deep groove ball bearings.
so please correct me if I'm wrong:
1 You don't need pre axial loading in the case single row bearings.
2 if you dont provide pre axial loading in the double row bearing there will be play
3 i can hold the single row bearing in place with press fit and a circlip


idontcare,
Formula Student India.

[Jay Lawrence]

Yes. Or no. It's one of those two, but idontcare

[Kevin Hayward]

First up doubts are dispelled by design (calculations and testing).

Play in your wheel bearings is bad (I will leave you to figure out why).

A pair of single row deep groove ball bearings is not an ideal solution for wheel bearings as they are more expensive and require careful thought and design to get the desired preload and installation stiffness. I would only go that way if you are doing so to gain a distinct advantage elsewhere.

Axial preload using a nut for your current solution is easier, cheaper and better for most hub/upright configurations. Don't change from that without good reason to do so.

The arrangement we developed early on at UWA used transition fits and custom made belville springs for preload. Preload amount was determined by puporse ground shims. Outer bearing rings rode up against the upright, ineers against the hub and retainer. No circlips required. However careful measurement and a sruface grinder was required. Belville washers aren't too hard to machine, but you will need to do all of the calculations. Compared to a nut on the hub it is a lot of work (not to mention that the bearings cost a lot more). We only did so to change our main hub and wheel centre design.

Also note that decent axial preload on these sorts of thin single row bearings can drastically reduce the life of the bearings, which you need to account for. Make sure to space them out quite a lot to reduce the resultant vertical load to resist the moment from cornering.

...

A bit of history about when this bearing arrangement started to become common in FSAE:

We were one of the first FSAE teams to go that direction with bearings. Although I should note that we originally were following the Saxon hillclimb design of Martin Ogilvie. At the time the vehicle was lighter than most of the front runners in FSAE with a bigger engine (and small wings). Apart from needing a taller rollhoop and obvious powertrain changes it would have been close to legal for FSAE. Since then the template rules and a number of other changes have pushed the Saxon and FSAE further apart. Although it is still well worth looking at for inspiration. I have put a link to an online write-up below. At the time of developing the 2003 UWA car we contacted the magazine that published the article and got a copy of a lot of unused photos that were taken during the shoot. Some that highlighted some of the technical details very well. From there we reversed engineered the main areas and proceeded to modify to suit, including cheap simple molds and developing a much cheaper way to cure pre-preg carbon fibre.

http://www.sbdev.co.uk/History_files...idinglight.htm

The UWA version is below:

http://www.motorsport.uwa.edu.au:8090/display/UWAM/2003

Out of interest the car didn't finish that well with a dnf (actually finished, but the large driver change-over time in endurance meant the time was outside the maximum allowed) in Australia and a wet autocross/endurance run in the US (freak storm that split the comp into wet/dry). However it won design in both comps and set the ground-work for quite a few successful years following it. It was also a pain in the butt to work on and was quite quite cramped around the arms and shoulders making it difficult to drive. Definitely a love-hate relationship with that car. The bearing arrangement worked fine and was carried on for quite a while, but like everything on that car I wouldn't have called it easy to implement.

Kev

[idontcare]

kev,
thanks for your reply

I wasn't planning to go for a pair of single row DGBB. I was talking about only one DGBB per wheel. Our university's BAJA team had used such arrangement last year and were successful.

[Kevin Hayward]

idontcare,

I'm sorry but one single deep groove ball bearing per wheel makes absolutely no sense at all. I am assuming you realise the bearing arrangement needs to resist moments ...

Kev