Looks like I'm on my own here. Well I cant start untill I mix up this big glass of icy cold milk, a level teaspoon of coffee, two spoons of sugar and some ice. Let's see now, (mix-mix stir-stir), bearings come in dozens of forms and sizes and in vastly differing grades of quality. They are all designed to reduce the friction between rotating or sliding components, hense the more popular term, Anti-friction bearings. The most common and most well known are the Deep Groove series of Ball Bearings. (Sip-sip, ahh, yummy).
Most of the cheaper wheels like wheelbarrow wheels have very crude and sloppy and rough bearings. They do their job only because they dont revolve at high rpm's. If these low quality bearings are used for any high speed (800 rpm and greater) plus carry a reasonable load, the cheap bearings will die. They can either fall apart or sieze up. Failure of the bearing in either way can result in lots of excitement including lots of pain. (sip-sip).
A bearing that runs roughly, makes a low rumble sound. This sound can only be produced by energy that is being syphoned off from the energy driving the S/Y. You would be shocked to see how much energy (forward motion) is lost by rough, noisey bearings. For a family day of cruising the beaches and salt lakes, who cares about a few decibels of rumbling, noisey and dying bearings? If you want to win races, then things suddenly become very different and technical. (sip-sip).
Choosing the correct bearing type is critical for success. The Deep Groove bearing (also called a cartridge bearing - a very poor use of terminology) can be bought with seals or shields. The seals are supposed to keep out the dirt and foreign crud and protect the precious race-ways and balls. They certainly will do a fair job of this (sip-sip) but at a high cost. The cost takes the form of friction, the very thing we dont want. This friction comes from the use of the seals. The seals fit rather tightly on the side faces of the bearing. The shields are simply just that. A shield on the side of the bearing to deflect most of the dirt and rubish that comes along. They will NOT keep out sand. Seals and shields can be on one side or both sides of the bearing.
Because of the limited energy availabe to power the S/Y it is essential that the very best bearings and seals be used for competition or even to keep maintenance down to a minimum.
A better style of bearing is the Angular Contact Bearing. This bearing can handle axial loads that a deep groove bearing cant withstand, especialy if the D/G bearing is badly worn. (sip-sip, hmmmm, more ice is needed)
Such bearings require specialised equipment to instal, (a lathe and other tools). To farm the bearing housings out would be far too expensive for many people to instal. If you can DIY for the housings, then the gains would be, in my opinion, well worth the effort.
Perhaps this thread should have been about the use of seals. It is in the choice of seals that an important race can be won or lost. There are hundreds of seal types, far too many for me to discuss here tonight.(sip-sip).
The housing that I described in an earlier post uses Angular Contact bearings and only one special seal. The bearings will run in an oil bath as grease has too much drag. There is another style of bearing that is the absolute best one of all. This bearing is called a Needle Bearing.
Needle bearings have enormous advantages over any other bearing. The greatest is that they have almost no inertia. They allow a machine to accelerate to maximum velocity in the minimum of time. They can carry huge loads and run (revolve) at very high rpm's. They are tolerant of some misalignment and are easy to instal. (sip-sip). They are very economical to buy and easy to obtain. They perform best in an oil bath but will operate with success if lubed with a suitable grease. Did I mention the small downside of these bearings? The downside is that needle bearings are NOT designed to carry any axial loads. To use a needle bearing requires a thrust bearing fitted at each end of the hub. To fit thrust bearings requires careful design of the hub and a lathe to make the housings. So after all this preamble, we have come full circle and back to the common Deep Groove ball bearing. (sip-sip).
To install a rough running bearing and run it to wear it in or whatever you do to make it spin freely is simply building on a false hope. Yes, I have seen the photos of siezed bearings in plastic wheels and no comment is needed.
High quality deep groove bearings are hard to beat if installed for otimum performance. This means run them in oil, use a precision made hub if possible and choose the oil seal very carefully. The truly ultimate way to go, is to use Angular Contact bearings set up in a hub the same as my design or similar. Perhaps one day, I might design a hub with needle bearings and a thrust bearing at each end. It would be a great way to get a comparison of the two bearing types. Enjoy.
(sip-sip) Oh, I need a refil!

Kody

Hey Kody,
Good read. Your sip-sips I could hear from here. Go on admit it, you are SLURPING the stuff.

You haven't had iced coffee until you have had one of mine. It goes like this:- A suitable amount of crushed ice to which is added One part Kahlua (not Tia Maria), one part Creme de Cacao (brown), three or more parts thick cream to personal taste. Shake (not blend or stir) vigorously in suitable shaker. Pour,SIP, enjoy. Use caution when applying to members of the fairer sex, or not.[}:)]

If it is a cool evening or you wish to add more gaiety, to the initial ingredients add one part Mount Gay Genuine Eclipse Barbados Rum (or other quality Carribean Rum).

This is known as a "Sombrero" because "Eeef you have six of deese senorita, you will become an expert at doin' de Mexican Hat Dance on zee table with no clothes on!!"

What do you know about "ZZ" bearings Kody? Some blokarters are using those.

Adios Amigos!!

Hi Cisco,
I really need more info about what is meant by a "ZZ" bearing. The prefix is used with Steel bearings and also with Ceramic bearings. The Ceramic bearings can be quite expensive and I would guess that these are not what you are asking about (???).
A Steel Ball Bearing (BB) is also designated "ZZ" if the bearing has two "Shields" instead of two "Seals". There is a big advantage that the two Shields can offer but it comes at a cost (doesn't everything?).
Standard Seals on a BB create a lot of drag on the rotating part of the BB. This drag can be very costly in terms of aceleration and achievable velocity, (speed). The BIG advantage of seals is exactly that! The BB is fully sealed and the balls and raceways are very well protected when opperating in normal clean engineering environments. When used on a S/Y, the seals can't cope with the environment for as long a time. They will still do an excellent job for what is required of them but there is lots of friction. This friction could cost you the most important race of the year at its worst extent.
So lets find something that has NO friction inbuilt into the BB. Enter the ZZ BB's. These bearings as mentioned come at a high cost. The shields keep only some of the dirt, sand and crud out of the bearing. The shielded BB will spin faster but when (not "if") the sand enters the raceways it will destroy the BB. The bearing will jamb up and usually ('cos of the weight on the wheels) crunch up the sand and the BB will keep running --- for a short while. If the BB decides to do a complete croak, things can again get very exciting if the S/Y is moving at high speed. If a BlowCart is running on a "sealed" surface, eg. bitumen, then ZZ BB's can offer a big advantage if used with a "soft" Lithium Grease, ie, a very low viscosity. Run the ZZ BB's on a dirt surface and they will eventually fail same as when run on the beach. Contamination and corrosion are what destroys a bearing regardless of what it is made from. Keep the big CC's away from the bearings and they will last a long time.
Next time, I will chat about seals. No, not the seals that swim and eat fish, the other kind.
PS, If I had just one of your "iced coffee's", I would be trying to sail the L/Y over to great Keppel Island; but they sound good.

Kody