[TowerTalk] Bearings for Axial Load

Grant Saviers grants2 at pacbell.net
Sat Jul 15 23:27:49 EDT 2017

For single row tapered roller bearings, they work as Roger describes.  
They will fall apart so need retained and preload applied to insure 
everything stays in contact when load is applied. A car produces push, 
pull, and radial loads on the wheel tapered roller bearings.  The parts 
are the cup and cone (goes on the shaft) and are purchased separately 
for larger bearings.

The spherical dual roller bearing described in the post that started the 
thread is designed to accommodate significant shaft angular 
misalignment.  That would occur when the tower leans in strong wind.  
They are not intended to come apart and the preload/clearance is 
established in the precise grinding of the parts.

More on bearings:  Needle bearings have no axial load capacity and 
thrust ball or roller bearings have essentially no radial capacity. In 
between are angular contact bearings, usually made in super tolerances  
(ABEC 7 or 9) for machine tool spindles.  These spindles need to handle 
loads in all directions.  They come in matched pairs, and a Bridgeport 
mill set (not Chinese) costs ~$700.  Some models of rotators (Yaesu, 
HyGain) have the aluminum races shaped as angular contact bearings so 
both axial and radial loads can be applied.

Deep groove ball bearings are primarily radial bearings but can handle 
axial loads of 25% or more of rated radial load per specs.

Grant KZ1W

   On 7/15/2017 19:32 PM, Roger (K8RI) on TT wrote:
> I'm not a mechanical engineer, but pretty sure. Those bearings receive 
> a substantial load, not only on both axes, (cornering) but off axis as 
> well. (momentary or short term impacts).  The race is not only tilted, 
> but tapered so those rollers support load along their entire lengths.  
> Note, the race taper is roughly 20 degrees off horizontal as the 
> primary, long term is horizontal, while short term (but substantial) 
> loads are mainly, or close to, in line with the axles although impacts 
> may be at almost any angle off the rims.
> 73, Roger (K8RI)
> On 7/15/2017 Saturday 12:20 PM, Jim Thomson wrote:
>> Date: Sat, 15 Jul 2017 01:56:37 -0400
>> From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk at tm.net>
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Bearings for Axial Load
>> <Roller and ball bearings work well for side loads. Ball bearings in a
>> <horizontal race can support substantial loads. Roller ans ball bearings
>> <typically work in one axis at a tine.  It takes a tapered bearing, like
>> <a wheel bearing to do well on both axes.
>> <73, Roger (K8RI)
>> ##  u sure about that ?  A tapered bearing, like a wheel bearing, is 
>> designed
>> to be mounted horizontal.   Mount it vertical, and all the load ends 
>> up on the bottoms
>> of those shafts that go through the  tapered bearings... on the now 
>> horz section, that all those
>> vert shafts are connected to. .  Im sure it was on your site that
>> depicted broken shafts..that go through the center of the tapered 
>> roller bearing.  IF the wheel bearing was
>> big enough to begin with, and 2 of them were used, it should not be 
>> an issue.  IF the rotor in question had
>> the entire weight  of the mast + ants  on it, then there would be no  
>> weight on the bearings either... only
>> an axial load, when the wind blows.... moot point.
>> ##  I dont know what type of bearing the speer brand is..... thats 
>> used in the UST crank-ups, but they are
>> built like a tank...and come with locking collars.   I used 2 of 
>> em... + a K7NV  small PP.
>> Jim  VE7RF.
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