Hub nut concern(s)

kenmyfam

kenmyfam

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Re: Hub nut concern(s)

Was not going to get into this either and did not want to start anything other than healthy discussion.
However if you take expansion into consideration in a taper fit situation both pieces will expand towards each other thus increasing any force against each other.
I promise to comment no further and am not being critical of how anyone sets their bearings. Personal choice.
 
bigdee

bigdee

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Re: Hub nut concern(s)

kenmyfam said:
Was not going to get into this either and did not want to start anything other than healthy discussion.
However if you take expansion into consideration in a taper fit situation both pieces will expand towards each other thus increasing any force against each other.
I promise to comment no further and am not being critical of how anyone sets their bearings. Personal choice.
Click to expand...

Excellent point. As a general rule tapered bearing pairs are set by end play and radial ball bearings are set with a preload.
 
Frank Acampora

Frank Acampora

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Re: Hub nut concern(s)

Didn't you guys ever take high school physics?

The bearing inner race and rollers will expand outward under heat BUT---the outer race will also expand outward equally. (When you heat a circle it expands so the inner diameter INCREASES That's why we heat bolt holes to free stuck bolts.) THUS: clearance will remain the same. Additionally, the spindle will lengthen longitudinally, increasing clearance. But the hub will also lengthen longitudinally, decreasing clearance equally. Thus, clearance will remain the same under influence of self generated heat. And heating WILL be equal because heat is generated by hysteresis of the grease and work done by the wheel turning the bearings. Thus the whole hub, bearing, and spindle assembly is for all intents and purposes heated equally.

Sheesh!
 
smokeonthewater

smokeonthewater

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Re: Hub nut concern(s)

sheesh urself... it will NOT be equal unless all parts measured are identical the shape of the part also has a hand in determining expansion rate
 
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Fed

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Re: Hub nut concern(s)

What I find interesting is Timken call for free play yet Ford say to pre load.
Perhaps it doesn't matter so long as they're not over tightened or flopping all over the place.
 
T

tinkerguy70

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Re: Hub nut concern(s)

Fed said:
What I find interesting is Timken call for free play yet Ford say to pre load.
Perhaps it doesn't matter so long as they're not over tightened or flopping all over the place.
Click to expand...

I would think that would be the most logical assumption made yet.

Then again, if you poke around on the Timken site, you really can't get a definite answer one way or the other. Or at least I couldn't find one. Maybe more details are out there somewhere, I dunno, I didn't spend a great deal of time on it, but I did look. YMMV.
 
bigdee

bigdee

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Re: Hub nut concern(s)

Fed said:
What I find interesting is Timken call for free play yet Ford say to pre load.
Perhaps it doesn't matter so long as they're not over tightened or flopping all over the place.
Click to expand...

We are referring to simple BOAT TRAILER bearings which demand zero preload. The Ford application is different and allows for preload. Just to keep it simple, trailer bearings should NEVER be preloaded. I never question sound engineering data.
 
smokeonthewater

smokeonthewater

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Re: Hub nut concern(s)

but airplane tires get inflated to 200 psi, how could a trailer be right at 50????? LOL

I think the BEST advice would be to consult the manufacturer of the trailer bearings in question... as stated above timken says .004-.007... really kind of makes the rest of this chit silly.
 
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UncleWillie

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Re: Hub nut concern(s)

Frank has it Correct!

The shape if the part has no effect in the expansion rate; The coefficient of expansion controls everything.

The classic example is to consider a large block of metal with a relatively small hole in the middle of it.
The question is posed; As the block of metal is heated, does the hole get larger or smaller?

The intuitive answer is that the metal expands towards the hole and the hole gets smaller. Incorrect!

In actuality the entire blocks expands proportionally in all 3 dimensions and the hole gets larger proportionately.
The effect is the equivalent to taking a picture of the object and then enlarging the picture, everything gets larger but the proportions remain the same!

This is why it is easy to press in a bearing if you heat the bearing mount and cool the bearing.
The hole gets bigger and the bearing gets smaller.
Press quickly, as the effect vanishes very soon after the parts come in contact and the temperatures equalize.
 
smokeonthewater

smokeonthewater

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Re: Hub nut concern(s)

well yes IF everything is heated evenly BUT shaped parts dissipate heat and absorb it irregularly...

In the same scenario as above, if you were to focus heat on the 1/4" of metal surrounding the hole in the center of the large block would the hole not have the potential to shrink ? serious question....

also, a spindle being cooled by contact with the axle tube hanging in the wind and a hub being heated by it's connection to hot brakes will most definitely not heat evenly.

I CAN say first hand that I've had trailer wheel bearings that ran hotter than others on the ame trailer and after backing off the spindle nut slightly they ran cooler. Maybe not super relevant but.....
 
bigdee

bigdee

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Re: Hub nut concern(s)

UncleWillie said:
Frank has it Correct!

The shape if the part has no effect in the expansion rate; The coefficient of expansion controls everything.
Click to expand...

This is only true for a single mass. Multiple components expand at different rates until thermal equilibrium is reached. I hate to keep beating a dead horse but is it more prudent to listen to laymen (some) on a boat forum or to the application Engineers at Timken.
 
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tinkerguy70

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Re: Hub nut concern(s)

smokeonthewater said:
but airplane tires get inflated to 200 psi, how could a trailer be right at 50????? LOL

I think the BEST advice would be to consult the manufacturer of the trailer bearings in question... as stated above timken says .004-.007... really kind of makes the rest of this chit silly.
Click to expand...

Not starting a fight here, but can you provide a source for that information?
As stated, I have looked and haven't found anything that is even close to an answer on the Timken site.
 
kenmyfam

kenmyfam

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Re: Hub nut concern(s)

Said my piece and staying quiet as promised :lol::D
 
smokeonthewater

smokeonthewater

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Re: Hub nut concern(s)

tinkerguy70 said:
Not starting a fight here, but can you provide a source for that information?
As stated, I have looked and haven't found anything that is even close to an answer on the Timken site.
Click to expand...
I was quoting bigdee.... He is the one that stated it as coming from timkin
 
bigdee

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smokeonthewater

smokeonthewater

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Re: Hub nut concern(s)

well that is stated to be for an automotive application but I just can't see how a boat spindle would need to be tighter than a non driven automotive wheel which just happens to be set up the same as the driven wheel...
 
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