[TowerTalk] Re: Thrust bearing

[Jerry Keller]

Sorry, in my previous post I should have mentioned:

My top "thrust bearing" is actually what N4NM calls a "pointy-top"... a tube attached to the top tower section thru which the mast passes... which acts as a guide. Inside the tube, the mast is protected to some degree against chafing by a thin polyethylene sheet wrapped around the mast as a bearing, plus plenty of grease. I used rubber plumbing adaptors ("Furnco's") as grease retainers top & bottom... one end hose-clamped to the mast and the other end a loose fit on the guide tube.  But the important point is that nearly all the weight is supported by those double-saddled muffler clamps sitting on the REAL thrust bearing that's between the guide tube and the rotator. I don't even use the setscrews, so scoring, etc, is not an issue.  I would think that using two actual TB's would work as well.

Rotator removal is not a problem because my tower tilts over, but if it didn't the TB taking the weight would allow me to R&R the rotator without disturbing the mast or antennas.

73,  Jerry K3BZ
  ----- Original Message ----- 
  From: kb9cry at comcast.net 
  To: Noel ; towertalk at contesting.com 
  Sent: Thursday, July 22, 2004 2:46 PM
  Subject: RE: [TowerTalk] Re: Thrust bearing


  I have TB-3 on my towers and what I do is set the mast down into and resting on the rotator.  I center the mast in the thrust bearing and tighten the collar screws, really just to keep it centered.  I then install a small SS pipe clamp onto the mast and move it down the mast so it is up against the top of the bearing.  I then install the antenna.  My assumption is that some of the additional load from the antenna is being borne by the TB.  Seems to work for me.  If I need to remove the rotator, I've installed another pipe clamp up the mast above the top bearing plate and used a small scissors jack to jack the mast assembly up and out of the rotator.  On the new tower I might attach a come-along to a clamp attached on the mast just above the rotator and jack it up that way.  Phil  KB9CRY

  -------------- Original message -------------- 

  > Agreed with everthing except the statement. "...Then make sure the 
  > collar can rotate around the mast without binding".. Seems to defeat the 
  > point of having a thrust bearing? Why not have just a collar then? I 
  > think the bolts in the thrust bearing should be tightly holding the mast 
  > or at least very snug. Not bearing weight but enough to support any 
  > lateral movement. Your method would cause the bolts to eventually scar 
  > the mast even though you say the clearance is minimal, unless one used 
  > shims. 
  > 
  > I'm curious haw many people who utilize thrust bearings, allow the 
  > bearing to "rotate around the mast" or make sure the mast and bearing 
  > are tight and rotate together? 
  > 
  > 
  > Noel 
  > 
  > 
  > _______________________________________________ 
  > 
  > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather 
  > Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions 
  > and ask for Sherman, W2FLA. 
  > 
  > _______________________________________________ 
  > TowerTalk mailing list 
  > TowerTalk at contesting.com 
  > http://lists.contesting.com/mailman/listinfo/towertalk 
  _______________________________________________

  See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

  _______________________________________________
  TowerTalk mailing list
  TowerTalk at contesting.com
  http://lists.contesting.com/mailman/listinfo/towertalk