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  #21  
Old 06-22-2012, 04:42 PM
lancef53 lancef53 is offline
 
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Neat setup--

It is amazing how many people struggle to understand the difference in a ball bearing and a cone and cup type bearing, and the preload issue.

How much for just the bearing mod? No tire trueing or balancing.
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  #22  
Old 06-22-2012, 05:54 PM
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CharlieWaffles CharlieWaffles is offline
 
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Quote:
Originally Posted by flion View Post
Are you going to do this for the RV-10 mains as well?
Did this ever get answered?
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  #23  
Old 06-22-2012, 07:40 PM
szicree szicree is offline
 
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Originally Posted by lancef53 View Post
Neat setup--

It is amazing how many people struggle to understand the difference in a ball bearing and a cone and cup type bearing, and the preload issue.
There is no difficulty understanding the difference here. The fact is that if you tighten these sealed bearings only hand tight, they will, with a very small amount of wear, begin to turn on the axle shaft. To prevent this, you would need to preload them axially which will in time only accelerate the wear, and so on. Similar bearings are the standard in cars, motorcycles, bicycles, skateboards, etc. and always have a center spacer. I believe Bob K. voiced legitimate concerns and was rewarded with what came across as sarcasm.
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  #24  
Old 06-22-2012, 09:36 PM
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PerfTech PerfTech is offline
 
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Originally Posted by szicree View Post
Based on your company videos I am led to believe that the nose wheel does get a spacer. Why is it desirable on the front but not needed on the mains? In fact, the video says that the front gets tightened down to prevent things from rotating on the shaft, which is exactly one of the concerns expressed in this thread.
...Actually the front wheel is a completely different type of application. The front fits inside of the fork and the 3/8" bolt is in essence the axle. It is not very substantial when used in this manor. You can not tighten it up as this will lock the wheel if you are using tapered bearings. Thus when it is stressed even a small amount it deflects and a misalignment of the bearings occurs. This in turn makes the entire wheel, tire and spacers lock and spin in the fork exerting considerable force on the gear leg and galling the fork and spacers. The center spacer on the nose wheel is necessary so you can tighten the bolt without locking up the assembly. These tapered roller bearings were actually designed to be on a spindle mount like the mains and other than being messy and requiring service they do a pretty good job. They are several times overkill for the job being done on these airplanes. The same part number bearings are used on many older GM products, Camaro, Firebird, some 3/4 ton trucks Etc. where they last a couple of hundred thousand miles under very severe conditions or the equivalent of perhaps a half a million landings.
...Now the stock mains are these same roller bearings being used as intended on a spindle. You do not tighten them up tight with the spindle nut or they will burn up. You only turn the spindle nut to remove side play and then install the cotter key. Nether the old roller or new ball bearings will turn on the spindle as nothing has changed. If a piece of dirt or foreign material gets in the rollers the bearing will lock and spin on the spindle and is designed to do so. The new bearings we use are fitted the exact same way and only require removing the play just like the originals. When I submitted to Timken a detailed drawing of the aluminum wheels we use on our RVs they told me that the wheels under all axial and radial load conditions will fail long before the bearings. I am not saying these new bearings are stronger than the original bearings, but the original ones are far and away overkill and do require regular attention. I prefer the new maintenance free set-up that we are offering and have complete faith in the engineering department of Timken Bearing. They make every type of bearing available including the originals we are removing and I have no reason to think they would mislead us on this application. I will say this, a center stack-up spacer will have no negative effects and will distribute the load over the two bearings evenly. We will provide one if you desire it, but it isn't necessary if you are not comfortable with this then for sure, please do not purchase this service. I will be happy to discuss this and answer any questions I can so feel free to call us. Regards all, Allan...
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  #25  
Old 06-22-2012, 09:55 PM
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PerfTech PerfTech is offline
 
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Quote:
Originally Posted by szicree View Post
There is no difficulty understanding the difference here. The fact is that if you tighten these sealed bearings only hand tight, they will, with a very small amount of wear, begin to turn on the axle shaft. To prevent this, you would need to preload them axially which will in time only accelerate the wear, and so on. Similar bearings are the standard in cars, motorcycles, bicycles, skateboards, etc. and always have a center spacer. I believe Bob K. voiced legitimate concerns and was rewarded with what came across as sarcasm.
... The new bearings will have no more tenancy to rotate on the spindle than the tapered rollers as they are far less drag than the roller bearings.
...Perhaps I do need to apologize to Bob K. I was only trying to tease him a little and went about it obviously in the wrong way. Sorry for that Bob, guess I owe you one, or visa-verse. In a previous post I said we will provide a center stack-up spacer to anyone who desires one. Thanks, Allan...
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  #26  
Old 06-22-2012, 10:42 PM
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PerfTech PerfTech is offline
 
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Did this ever get answered?
Sorry, I didn't see your question until now. Yes we will be offering this for the 10 as well, with or without the spacer. Thanks, Allan...
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  #27  
Old 06-23-2012, 09:29 AM
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Toobuilder Toobuilder is offline
 
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Default Agree with the need for a spacer...

If you have a single sealed ball bearing the inner race is locked to the axle by the torque of the retaining nut, right? You could apply as much torque to the nut and still not affect the bearing preload one bit. Unless you are using bearings in a very low stress environment like a lawnmower, childs wagon, etc (using a simple cotter pin on the axle), you lock the inner race to the axle with the retaining nut torque. In an instance where you have more than one bearing, there must be a method to lock all the inner races to the axle through one nut - and that simply requires a solid spacer. This spacer needs to be exactly sized to be slightly larger than the wheel so that no matter how tight you get the nut, there will be no induced sideload on the bearing. This also should take into account the rate of thermal expansion of the aluminum and the axle.

In any case, simply using the nut as a "cap" to keep the wheel from falling off is a mistake, IMHO. Since you can't even touch the inner race with the nut without inducing sideload (without a spacer), you are counting on only the residual friction of the inner race on the axle to keep it fron turning, and that will eventually bite you. Once that inner race spins, you are buying a new gear leg.
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  #28  
Old 06-23-2012, 11:38 AM
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PerfTech PerfTech is offline
 
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Quote:
Originally Posted by Toobuilder View Post
If you have a single sealed ball bearing the inner race is locked to the axle by the torque of the retaining nut, right? You could apply as much torque to the nut and still not affect the bearing preload one bit. Unless you are using bearings in a very low stress environment like a lawnmower, childs wagon, etc (using a simple cotter pin on the axle), you lock the inner race to the axle with the retaining nut torque. In an instance where you have more than one bearing, there must be a method to lock all the inner races to the axle through one nut - and that simply requires a solid spacer. This spacer needs to be exactly sized to be slightly larger than the wheel so that no matter how tight you get the nut, there will be no induced sideload on the bearing. This also should take into account the rate of thermal expansion of the aluminum and the axle.

In any case, simply using the nut as a "cap" to keep the wheel from falling off is a mistake, IMHO. Since you can't even touch the inner race with the nut without inducing sideload (without a spacer), you are counting on only the residual friction of the inner race on the axle to keep it fron turning, and that will eventually bite you. Once that inner race spins, you are buying a new gear leg.
... This is the way ALL RVs are made!!!!!!!!!!
Also several billion automobiles front wheels!!!!!!!!!
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  #29  
Old 06-23-2012, 01:12 PM
gasman gasman is offline
 
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Allan, maybe if you show a cutaway view of the bearing and show how it is designed to take side loads, it would help resolve this issue.
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  #30  
Old 06-23-2012, 02:05 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by PerfTech View Post
... This is the way ALL RVs are made!!!!!!!!!!
Also several billion automobiles front wheels!!!!!!!!!
There is a difference between tapered roller and ball type bearings.
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