View Full Version : how do wheels work?
07-09-2003, 07:39 AM
Do they rotate around the axle or on the bearings or both? What do bearing spacers do? Why do the wheels bind if I tighten my axles too tight, and is it safe to leave the axles relatively loose? Rookie questions, I know; I only ask that you answer my questions while you mock me.
07-09-2003, 10:22 AM
Mike needs to give you the conceptualizations behind the wheel/bearing/axle energy transfer...
Bearing spacers, when engineered correctly, lock the chassis to the axle assembly, and the wheel then rotates around the bearings (I think). You should be able to tighten the chassis down to the point of stripping the axle bolt threads with no fear of locking the wheels...
If you have skates that lock the chassis to the bearings when tightened, then you maybe need different skates?
Even some otherwise reputable models of skates are weak in this area. You should be able to roll and step in your skates with no noise, or "clack" when your skates contact the floor. Maybe a "clump" sound if the polyeurethane wheels strike the floor with enough force, but no metallic or rattley clanking at all.
You should roll silent.
Hope that helps...
<font color=purple>DannyG</font color=purple>
Danny is basically correct and if the chassis frames are improperly machined (not parellel at the "bosses") they can cause bearings to bind when tightening
If it is not the chassis (which is actually less likely) the "locking wheel" problem has two causes if it happens as you progressively tighten the wheels.
There have been problems with wheel hubs (hard plastic part in the middle of the wheel) and the bearing spacers being improperly manufactured - which are the two most common problems. The way the system works is as follows:
On the inside of your chassis frames you will notice a "boss" or raised section where the axle bolt goes through the frame. The outer shoulder of the inner races (small metal sleeve in the very center of the bearing) should be pressed evenly against these two "bosses" when they have been assembled in the wheel and the axle bolt is tightened.
However when you put the bearings into the wheel you have noticed the small aluminim sleeve(there are basically two different kinds used) that go in between the bearings. One kind just fits between the two bearings, and the other actually slides through the inner races of the two bearings. The second kind will have a shoulder (which is simply a section of larger diameter in the middle of the spacer).
Both of these spacers do the same thing then - press against the inside inner races of the bearings when the axle "bolt" is tightened. So the inside shoulders on the chassis frames press against the outer surface of the inner races of the bearings which then squeeze agaisnt the "spacer". Effectively this "locks up" the inner races - allowing the balls of the bearing to rotate freely around and on the inner race.
On the outside diameter of the bearing you have a "sleeve" of metal as well - which is called the "outer race".
These "band" actually have a "groove" machined into it where the bearing balls ride. The tolerance(simply how tight they fit) of the balls to these grooves(there is one in the "inner race as well) basically determines your Abec rating. The smaller the tolerance (play) in the bearing - the higher the ABEC rating of the bearing.
You may also have noticed a small undercut or "shoulder" on the inside of the plastic wheel hub. This is what stops the bearing from going right through the wheel when you push them into your wheels. If this shoulder section is too wide or made crooked however, it may prevent the bearing from being pulled evenly together(where the grooves in both races and the balls are all alligned evenly) when you tighten the axle causing the bearing to "load up" or bind as you tighten. The width of that hub "shoulder" and the width of the bearing spacer, should at worst be uniform and identical, and or even better should have the "wheel hub shoulder" about 002" - 005" smaller than the width of the spacer.
So as you can see(I hope) if the spacer is too narrow in width or the "wheel hub shoulder" too wide, the bearing balls will begin to press against the sides of the "grooves" of the races, causing the bearing to bind up when you tighten the axle. Most of these problems are errors of only .005" - .010" and have occurred within the manufacturing of many suppliers of wheels and spacers. If the binding is extreme, then different wheels or spacers may be required. If you have already tried several different sets of wheels and spacers and the problem persists - it may in fact be the chassis frames which are improperley manufactured. It is more often not the frames and spacers, but the wheel hubs which cause the problem.
And the inner races are not meant to spin. The only part of the bearing which should move are the balls around the inner race, and the outer race around the balls.
07-12-2003, 02:31 PM
Uh, yeah...that's what I meant...
Seriously, thanks! Mike...good job as usual...
Folks, this is one reason why this internet group discussion site is so valuable to people like myself who depend on knowledge to do their job the best. All you people out there who contribute thoughts, ideas, information, and yeah, even the emotions sometimes make this electronic conversation the best,
Keep it up...
<font color=purple>DannyG</font color=purple>
LOL sorry it was stronger than I........
07-13-2003, 09:31 AM
thanks guys - wow! OK, for the layman - I see you could try all sorts of combinations, but it seems like it would be easiest if you knew what subcomponents were on the "approved product list", ie, maybe Mission says "any Labeda wheels siz x fits this chassis, these bearings, these spacers" etc. Or does trial and error rule the day? thanks
The wheels are all supposed to be the same fit and sizes, IE 72/80's for some hi/lo's, 68/72's for some others(Hyper made one), 72/76 for some others etc. But the predominant wheels set ups are 72/80 for "hi lo's". There are some others I didn't mention too: 80,80,72,76 and a few more that some manufacturers have tried.
But the wheel hubs are all the same to fit either standard 688 bearings or minis.
What's abnormal is just some of the mistakes made by some of the manufacturers in casting the plastic wheel hubs or machining the spacers. I haven't seen bad spacers for a few years, but I have seen several wheels with bad hubs. And unless you are aware of this stuff - it can drive you nuts.
An easy test if you don't happen to have any micrometers hanging around is to install the wheels and try to "pop" them back and forth a little bit in the chassis. If they "pop" (it's a tiny amount) then the bearing has a little bit of play in the wheel - which is how it should be (just a few thousands.) If you can do this but still have the problem with the wheel binding as you tighten the axle, then most likely you do have a badly machined chassis.
There's no real approved list because most manufacturers don't admit they have a problem (Rink Rat did admit this - to their credit - and offered to replace any wheels having the problem) Almost all the manufacturers have has this problem with their wheels from time to time. The plastic hubs are probably made by a subcontractor to the wheel maker, and one or two of these subcontractors may have bad drawings or poor quality control on their product.
Bottom line is you never really know until you go to put the wheels on if there is a problem. Some of the Labeda Milleniums had this problem but not all and not all the different colors (durometers and compounds) had the problem at the same time. Had it happen with some CCM wheels too, also had some bad bearings too - just to further confuse the issue - they would never "loosen" up - had nothing to do with wheels or spacers although it took me hours to figure that out lol.
07-14-2003, 01:31 AM
...so I guess Mike is saying that sometimes the most scientific reasoning is just to say to yourself, "These wheels suck..." and get your money back to go get some different ones...
As an aside, belated congratulations to Simon on his participation on the National Junior Sports Festival East tourney team!
<font color=purple>DannyG</font color=purple>
07-14-2003, 04:05 PM
Holy cow, I am a maroon. So basically all modern wheels need spacers? I am using 10 year old skates, because I am playing on asphalt and the plastic shell of the boot holds up well. I don't think the original wheels had spacers - my hunch is they had two "wheel hub shoulders" built into the hub, top and bottom, in lieu of a spacer. Anyway, when I swapped wheels I didn't see spacers, so didn't insert any, I didn't even know there was such a thing until I started reading here. So I have been riding without spacers for some time, cursing the chassis but liking the boot. It is good to be humbled by my own ignorance once in a while, this should do me for about 6 months! Anyway, I really thank both you gentlemen for taking the time to explain it. I even printed your responses for future reference. In fact - Richard - what do you think about saving MD3s classic treatise to the library (like you did with the maintenance document from the gentleman from Sonic)? One last question on this thread for MD3, DannyG or anybody - did I ruin my current bearings by riding without spacers? thanks again
07-14-2003, 05:02 PM
Good suggestion. If MDE3 gives the OK, I'll be happy to do it. /wtimages/icons/smile.gif
Inline Hockey Central
LOL on the first one - but some wheels really do bind up...and if you put in new wheels with the same bearings on the same chassis with the original spacers and are having a problem - then it probably is time to take the wheels back.
Will pass on your congrats to Simon when he gets back Dan thank you, He is away at Torhs Nationals getting some "experience"(read "hat handed to him") playing Torhs Pro lol.
No need to feel like a "maroon" for asking the question - there are lots of people who have played for years who have never even thought about this stuff. Just some of us have spent too much time on these earth shattering questions.
As to your question on the bearings - let me put it this way - they may no longer hold up to much of an Abec rating lol - obviously if they make lots of growling noise - they are be due for a change.
Years ago there were several wheels and skate systems that used to little plastic "top hats" that fit through the center of the bearing when you assembled the wheels with the wide part to the outside. The ends of the smaller diameter sections would butt up to each other. Then there was an axle bolt and screw which went through this and the chassis. Those old plastic spacers used to get pretty chewed up if you played out doors at all and when worn could definitely cause the binding problem.
After that they used an aluminum or brass spacer which fit through both bearings on the inside and had a larger shoulder in the middle for the bearing to press up against. Some of these were hollow and had an axle bolt pass through the middle(Missions, earlier Labeda chassis, CCM's, earlier Tour's, Hyper chassis, and many others - 305's , 405's etc.), and some were threaded and had screws which went through the frames and screwed into this "spacer"(Bauers).
The most recent set ups which use a single threaded axle bolt which screws into the frame on the opposite side, is an aluminum spacer with a narrow larger diameter "ring" around the middle. This type just fits in between the bearings and does not go through them.
One way or another all the chassis/wheel/bearing combinations used some form of spacers. Most pro shops have a lot of different spacers in a "kit" box which they keep under the shelf - if you bring your skates in to one they may be able to fix you up. If you had the old plastic kind - probably not.
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