Different greases behave and age differently. It depends on whether the
proper grease was used as well. One telling point is the color of the
grease.
Most grease and in particular the older ones are a mix of oil, paraffin, and
soap, so yes they do get hard and waxy. Some gets quite hard in colder
temperatures and particularly after it's "well aged", or maybe aged not so
well. Some that are exposed to the elements can get very hard, but they
still tend to be waxy.
There are, and have been for many years some specialty greases for slow
moving, high pressure contacts. Silicone greases in particular are well
suited for this. Most Silicone greases are white. Never mix Silicone greases
with organic greases. Under pressure and friction the reaction will cause
the Silicone grease to break down into its basic constituents, the main one
being Silicon Dioxide, (powdered quartz better known as sand)
One of the best is High pressure greases is BR-2, (Beryllium Dioxide
Grease). It's messy, but works well up into the higher RPM range.
I don't remember the proper name of the grease but we affectionately called
it Bear S***. It was a thick, black, very gooey grease for very low RPM,
very high pressure grease. It was darn near like taffy and would not work at
anything other than very slow speeds. Get some on a finger and by days end
it'd be all over you and that stuff would NOT come off. It would also get
very stiff in cold weather. Cold for that was any where below the 40's and
it'd turn solid below freezing.
> Folks:
>
> We are stymied in our work to bring the Jamesburg 30 meter dish back into
I'm assuming Jamesburg is some where state side?
> 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
Are you sure there are no safety, or locking pins for the locking pin? It
would be normal to find at least one or two in this kind of assembly. Most
of this stuff is "stowed and locked".
> steel elevation motion system.
>
> See: http://www.longandflatsociety.com/Default.aspx?tabid=474
I'd need to see an image showing more of the mechanism so I could see how
it's supposed to operate.
My guess is the thing should have enough power to move even if the housing
were rusted remembering how some of that old stuff is built. As I said above
I'd expect to find some locking pins holding the large pin as well.
Does the piston/pin move in the lower housing shown? I'm assuming that is
the piece with the zerks.
If it does, I see the ends of two *rusted* steel bolts sticking out and I'd
guess they hold the pin in place. OTOH they may be the mounting pins that
hold the big one. I can't tell whether it's the threaded end sticking out or
the head end with the heads twisted off.
I'd not think many of the old greases would be hard enough to prevent the
thing from moving, but there are some that could. If parafin based grease is
known to be in there you can soften and eventually disolve it using Kerosean
which can be a messy job. I don't know if WD-40 would disolve it or not.
I'm assuming that the problem is not "petrified grease" as that is highly
improbable, but not impossible.
Probably the best penetrating oil to loosen something like this up would be
BP-Blaster. Dose it good, let set overnight and then give it a try. OTOH I'm
still betting on some locking pins some where in there.
If you, can please post a photo showing the over all mechanism and maybe
some with detail of the operating part.
>
> 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.
If you need it... and I can find it...I'd be glad to send you a new
cartridge of BR-2 Grease.
Good Luck,
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
> 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 aa6eg@hotmail.com;
> Skype: Sparky599
> Moon or Bust!--Jamesburg Gang Rides Again!
>
>
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