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Re: [TowerTalk] Very Old Grease Characteristics

To: Pat Barthelow <>
Subject: Re: [TowerTalk] Very Old Grease Characteristics
From: "John." <>
Date: Wed, 20 Dec 2006 21:46:57 -0600
List-post: <>
We in the past with similar type of assembly used a "Port a power" 
hydraulic pump.
We removed the pushing piston from the hose end and used the hydraulic pump
end screwed  the hose into the threads of the removed grease Zerk.

The idea is to use hydraulic   pressure from the port a power to loosen 
the old grease .

You may also fill the hose with solvent, Then the "Port a power" will 
push the solvent around the pin.

Be very carefull !~

de John KØCQW

Pat Barthelow wrote:

>We are stymied in our work to bring the Jamesburg 30 meter dish back into 
>operation.  The dish is currently in the "stowed" position, pointing 
>straight up.  It is locked in that position by a 3" diameter stainless steel 
>"pin" that is electrically driven up a cylinder, into a hole in the heavy 
>steel elevation motion  system.
>The pin's  close fitting cylinder-housing has zerk fittings for heavy grease 
>liube that probably had not been attended to in years, possibly decades.  
>The dish probably had not been the stow position for  decades, if ever, as, 
>it sat pointed at an Intelsat geosynchronous satellte, low to the horizon, 
>over the Pacific since 1968.   Two years ago, someone moved the dish to stow 
>position.  We, wanting to do moonbounce with the dish, have tried the two 
>ways to retract the pin to unlock the vertical motion, using the locking pin 
>motor drive, and the manual  crank, with no luck. We have hand cranked the 
>vertical motion support so as to remove any shear forces on the pin;  That 
>is, the pin is precisely centered in the close fitting  hole.   The pin is 
>so solidly stuck, it may as well have been epoxied into place.  Moderately 
>powerful forces have been used to try to push the pin down out of the locked 
>postion. to no avail.
>Some of us think there may be wear ridges inside the cylinder preventing pin 
>movement downward.   The pin is in some ways similar to a piston,  has a 
>connecting rod and wrist pin-like connection in its bottom for motorized 
>retractor/inserter drive.
>We are going to investigate that for possible cylinder interference,  in 
>detail our next visit.
>Others think that the 30 year old grease has fossilized to something akin to 
>epoxy, or coax seal,  and is keeping the pin from moving.
>My question is what does thick bearing grease evolve to in, say 30 years, if 
>untouched?   Stone?  Epoxy?   Grit?
>A parallel to normal towers might be a tower in decades long storage, that 
>had heavy greased cable pulleys.  Has anyone found 30 year old pulleys to be 
>jammed up hard with what used to be lube grease?
>73, DX, de Pat AA6EG;
>Skype: Sparky599
>Moon or Bust!--Jamesburg Gang Rides Again!
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