Thrust Bearing Xross section view

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Thrust Bearing Xross section view

Post by KJ6CYD » Sat Dec 26, 2009 11:18 pm

I need to make two thrust bearings for an antenna mast. I have two thrust bearings with a 2” id. What I am looking for is an idea or cross section view of how these bearings are retained and bolted to the plate of the tower. Any ideas or links appreciated. I do have a machine shop in my garage so machining these is no problem. Thanks and 73!

KJ6CYD, Larry

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Post by mechanicalmagic » Sat Dec 26, 2009 11:29 pm

For a low speed application, you cannot easily overload a 2" ID bearing with a mast. Typical axial loads are in the thousands of pounds, with a life of millions of revolutions.

If you have a bearing number, and an idea of the mast weight maybe we can help.

Dave J.

PS: What's a 73!
Every day I ask myself, "What's the most fun thing to do today."
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Post by Peter. » Sun Dec 27, 2009 9:28 am

I would simply use a pair of normal bearings. We have a drilling machine at work that uses two standard bearings and can carry a good ton and a half of load through them axially.

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Post by KJ6CYD » Sun Dec 27, 2009 12:16 pm

Hi Guys,

First, thank you for your interest in my request.

The bearings are INA/ANDREWS 2280 (NOS) purchased from eBay. One race ID. is slightly larger than the other, which I assume is to be able to accommodate an inside shield if so desired. The mast material is sch. 80 pipe with a nominal OD. of 1.9” . The expected height of the mast above the tower plate is around 5’ or so, with an overall length of 8’ to the rotator. At 3.631 pounds per foot for black pipe it equals 29 lbs. The weight of the antenna is yet to be determined, but should be no more than 100lbs.

The rpm of the rotator will be between, 1-3 revolutions per minute, able to turn 360 deg. with electronic preset stops to not exceed limits, clockwise and counter-clockwise operation on a horizontal plane relative to ground.

The overall idea is to relieve the weight carried by the rotator, to extend its service life and allow for easy removal of rotator from tower, if maintenance is needed.

What I am trying to accomplish is a bearing that is encapsulated inside a housing that can be bolted onto the plates of the antenna tower. Here is a link to a commercial thrust bearing. ... _r-tb3.html

Thanks again, KJ6CYD, Larry

P.S. The traditional expression "73" goes right back to the beginning of the landline telegraph days. It is found in some of the earliest editions of the numerical codes , each with a different definition, but each with the same idea in mind--it indicated that the end, or signature, was coining up. But there are no data to prove that any of these were used.

The first authentic use of 73 is in the publication The National Telegraph Review and Operators' Guide, first published in April 1857. At that time, 73 meant "My love to you!" Succeeding issues of this publication continued to use this definition of the term. Curiously enough, some of the other numerals then used have the same definition now that they had then, but within a short time, the use of 73 began to change.

In the National Telegraph Convention, the numeral was changed from the Valentine-type sentiment to a vague sign of fraternalism. Here, 73 was a greeting, a friendly "word" between operators and it was so used on all wires.

In 1859, the Western Union Company set up the standard "92 Code". A list of numerals from one to 92 was compiled to indicate a series of prepared phrases for use by the operators on the wires. Here, in the 92 Code, 73 changes from a fraternal sign to a very flowery "accept my compliments," which was in keeping with the florid language of that era.

Over the years from 1859 to 1900, the many manuals of telegraphy show variations of this meaning. Dodge's The Telegraph Instructor shows it merely as "compliments." The Twentieth Century Manual of Railway and Commercial Telegraphy defines it two ways, one listing as "my compliments to you;" but in the glossary of abbreviations it is merely "compliments." Theodore A. Edison's Telegraphy Self-Taught shows a return to "accept my compliments." By 1908, however, a later edition of the Dodge Manual gives us today's definition of "best regards" with a backward look at the older meaning in another part of the work where it also lists it as "compliments."

"Best regards" has remained ever since as the "put-it-down-in-black-and-white" meaning of 73 but it has acquired overtones of much warmer meaning. Today, amateurs use it more in the manner that James Reid had intended that it be used --a "friendly word between operators."

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Bear to find

Post by mechanicalmagic » Sun Dec 27, 2009 3:44 pm

Boy, that's a tough bearing to find.
But it seems you have a:
INA Axial deep groove ball bearings 2280
single direction, separable, inch sizes
d 2 inch
D 3,25 inch
T 0,813 inch
0,9 lbs Mass
9200 lbf Basic dynamic load rating, axial
22500 lbf Basic static load rating, axial
2800 1/min Limiting speed
as found on:! ... zb?clrsb=1

As you already know, it falls apart. These bearings are not made for a radial load, so either your housing must provide for a side load, or another bearing. OR, a clever design, which I will try to sketch.

OK, the way to use two thrust bearings:
The top bearing takes the downward weight.
The lower bearing is set upside down, so the mast cannot rise.
Since it cannot go up, or down, it cannot move out of the races.

Dave J.

Click the drawing for a bigger view.
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Post by whateg0 » Sun Dec 27, 2009 4:56 pm

To add to Dave's idea, which appears to use the body of the bearing assembly to limit side to side movement...

Not sure if it's possible, but the load doesn't seem too great, so I wouldn't think that it would be an issue. If the bearing races were made to capture the bearings, it could provide both axial and radial support. Think bicycle axle, but bigger.


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Post by KJ6CYD » Sat Jan 02, 2010 1:10 am

Made a simple drawing, not to scale. The epiphany is the special washer retainer that will keep the housing together and allow for maintenance if needed. What do you guys think? Thanks.

thrust bearing2.jpg
thrust bearing 2

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Post by Qst42know » Sat Jan 02, 2010 8:58 am

Is there a reason tapered roller bearings wouldn't work for this application?

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Post by GlennW » Sat Jan 02, 2010 9:15 am

Why not just a simple XLS-2 bearing? 2" ID, 3.3125 OD, X .625 W.

Not that it really needs it, but it is a 15° angular contact bearing.

Install it in a simple housing incorporating a seal to make it more weather tight.

What you have now is not weather proof at all if to be used out doors.

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Post by Bob C » Sun Jan 03, 2010 10:54 am


If you used Dave's drawing above but replaced the bearing and piece in blue with Ultra High Molecular Weight - PE it would be much simpler and cheaper. Like a hockey puck with a hole in the middle.

UHMW is very slippery and impervious to the weather. It is a very good low speed bearing material.
I think it would be worth looking into. Just my $.02 worth.

Bob C

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Followup on Bearings

Post by KJ6CYD » Sun Jan 17, 2010 2:49 pm

Here are a few pics of the bearing housings I made ala Dave suggestion. My design was not good (bad really :D ) and Dave was spot on. Only problem I had, like any home machinist is budget and material. Time I have lots of right now, rain, rain and more rain in California. Once again thanks guys and hope you approve. Paul now KT6G Extra Class Amateur Radio Operator.
thrust bearing4.JPG
thrust bearing3.JPG
thrust bearing2.JPG
Thrust Bearing.JPG

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Post by Russ Hanscom » Sun Jan 17, 2010 2:51 pm

Looks good and should be water resistant.

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