Understanding wheel bearing and hub design?

[zimbo]

Mornining PMs,/

I would like to understand the relationship of tapered roller bearings and thier placement on the axle of a trailer and hub and distance from the flange. Haven't found much at all out there, unless been asking the wrong question to Mr Google. There has to be some science behind it.

I have been making a few hubs these past 12 months for boat and small trailers and various farm implements out of cast iron.

Comparing the samples that have been coming in with same bearing size, the placement of the bearing seats are slighty different from each other.
Eg. bearing number 18690/18620. The distance from the seal outside edge edge to the flange is 26mm and 32 mm respectivley. The seal is 10mm thick. The flanges are 18-22mm wide, not sure this has any impact other than holding the wheel studs. The bearing sits right upto the seal.
The distance between the outside and inside bearing are vary. I would have thought that the bearings would be equidistant from the flange to absorb the radial load evenly as in the harrow bearing housing. Doesnt seem to be any standards, even the lands on the harrow spools vary from 3/4-1" thick, even in the same bearing size and there are 2 common sizes.

Would appreciate an explaination or a source I can read up on this. Would make my life easier.

Cheers,

 

[Limy Sami]

I'm no trained engineer or designer, but back in the day, when I built ag tackle combined with what I'd picked up from practical experience, tech college and books, I always endavoured to place angular contact bearings as far apart as possible.

In short, the wider apart - the longer they lasted.

 

[DDoug]

I have an old handbook from IIRC MRC bearings that has a section on the design
of bearing wheel hubs.

 

[Billtodd]

I'm no trained engineer or designer, but back in the day, when I built ag tackle combined with what I'd picked up from practical experience, tech college and books, I always endavoured to place angular contact bearings as far apart as possible.

In short, the wider apart - the longer they lasted.

Yes, there's a far great force from the side load during cornering , magnified by the lever of the wheel radius, than the typical static vertical load.

The wider they are apart the small the leverage.

 

[zimbo]

Thanks Limy.
This is basically the set up I have been seeing. So on the harrow with the bearing 1” apart there is not much turning as the gangs are fixed in place and are running straight hence the closeness.

Doug will search for that book online. Maybe it has a formula.

What would be the reason having a larger bearing on the inside and smaller bearing on the outside of the axle? To do with side load during turning?

Cheers.

Sent from my iPhone using Tapatalk

 

[Limy Sami]

Hi Zimbo, the images won't enlarge, ..............I suspect the larger bearing is to do with side load.

Had a prob on a set of discs (an't remember the make) years ago - eating bearings, ...I solved that by making a shaft carry 2 discs so the bearings were further apart, .....ISTR it was a lot of work and sodding about, but was worth it because the rest of the discs were very good, ..........I'm sure it was the hard Kentish clay and flints that knocked the gonads out of the standard set up -----------as it did much else

 

[Conrad Hoffman]

Proof once again that not everything you'd want to know is on the internet or findable with Google! If you can find a copy, Antifriction Bearings by Giovanni Conti, volume II, 1959, published by Hoepli, has an overview of every sort of axle, spindle and bearing system you can imagine. Not much math in terms of design equations though. No idea if one can find a copy. It does suggest that antifriction bearings might be a good search term.

 

[Nmbmxer]

What would be the reason having a larger bearing on the inside and smaller bearing on the outside of the axle?

I always thought that was to make it so you can assemble it easily.

 

[Erich]

If the axle is cantilevered, it needs to be larger at the base to carry loads, can be smaller at the end.
Saves weight, somewhat important on mobile equipment.

 

[neilho]

Search results from Bookfinder.com. $38. Volume 1 available, too.

 

[john.k]

I learned the hard way not to make trailer hubs.....the Chinese import trailer component sellers will have hubs under material cost in any size you want.....trailer hubs would generally be cast SG iron too,not plain grey iron.

 

[Rickyb]

Zimbo, you may be surprised to learn that wheel bearings are selected after the spindle is designed. Stresses in the spindle are highest at the inner bearing shoulder. Stresses there considering normal loads, impact loads, cornering and braking along with their frequency are used to determine the strength and fatigue life if the spindle. Spindles are safety related so much care is taken in the design to avoid failure. The bearing is selected after and near always have much excess capacity due to the diameter. Cartridge style bearings are another chapter.