I think a Sleeve bearing would have been better still. <:-))
>
> ## so far, on the new HDX-689 tower, the PEER brand thrust bearings, with
> their locking collars works good.
> The set screw for the locking collar has to be slopped with never seize
> goop though....and also more goop to be
> applied to the female thread.
>
> ## Thrust bearings are not easy to replace..after the fact.
That's what makes the wood and other split blocks so nice.
> The Rohn bearing's are not only expensive, they are poor value
> for the money, and poorly designed. If u do use the TB3/4's... add a zerk
> fitting, so at least u can pump it with grease
> once or twice per year.
I'm not sure if that will make them last any longer, but it will make
them run smoother.
73
Roger (K8RI)
>
## Roger, if you want things to go smoothly, start with the mast. Use either
a quality 87 ksi DOM mast... or
a heat treated 4130 chromolly mast [ 107-120 ksi]. Either way, make sure
they are hot dipped galvanized.
Ok, no rusting masts. On my HDX-689... they not only use a PEER brand thrust
bearing at the very top, I also have
a 2nd identical thrust bearing down aprx 4'. On the UST 689 tower, they also
use a.. 'sleeve bearing', just below the
top plate/bearing. This 2nd plate is aprx 6" below the top of the tower. A
section of pipe with an ID that's a tiny bit bigger
than 2" is welded into place..and runs between thrust bearing plate at top of
tower..and down 6" to 2nd plate . Both the top thrust
bearing plate and the 2nd plate are welded to the tower legs. [ the lower
thrust bearing + prop pitch plates are bolted into
place, so 4 x plates in all]. That short 6" sleeve pipe has nuts welded
to it, and 3/8" bolts. Their purpose is to pin the mast,
when working on the rotor. IE: mast is temp elevated 12"-18"...and 3/8"
set bolt through the sleeve bearing stops the mast
from free wheeling about.
## although both PEER brand bearings spun smooth, I replaced em both on
spec with new ones, since the tower is old, and the
bearings were not too expensive. I had no problem getting the locking
collars off either thrust bearing either. They provide an
indented hole on the locking collar to tighten the collar...with a few smacks
CW with a drift punch. The 2nd hole on the locking collar
is for the big set screw. As long as the set screw and mating female thread
on the collar are glopped with plenty of never seize
[ marine grade is the best version], you will never have a problem with em.
## I did have to replace the bad bearing on the end of the big rotor drum
though. the bearing was just fine, but the base had 2 x cracks
in it, right where the 5/8" bolt pass's through one end. [ both drum
bearings and thrust bearing are 2 x hole mount]. The bad bearing
had to be cut off, since it seized on the 2" solid shaft. After it was cut
off.... I could see the insides of those things are built like a tank !
## both drum bearings are the self aligning type, they will swivel a bit, and
factor in any mis-alignment. Now you think the thrust bearings
have some kinda big side load on em in a high wind, wait till you see the
side load on a 2" drum bearing ! Yikes, the entire weight of the
tower + mast/rotor/ants is on that lift cable [ with a 4:1 mech advantage]...
and the drum bearings are taking all the load.
Note, the very bottom tower section is sitting on concrete, so is not part of
the drum bearing load. Note, the ID of the drum bearings is a hair
less than 2"..while both thrust bearings have an ID that is a hair bigger
than 2". The drum bearings have a thicker base and are self aligning.
I checked peer's website..and no reason why u can't use their standard 2"
self aligning bearing for a thrust bearing, at top of the tower, or
their normal bearing [ no self aligning]..but with a thicker base.
## in the case of the UST towers, it's sorta a moot point, since that huge
6" sleeve that's welded between two plates is the ultimate ticket.
[ Plus both those plates are welded to tower legs. ] Between the sleeve and
the top thrust bearing, it will handle a massive side load.
## On the bottom thrust bearing [just above the prop pitch] I don't use
the locking collar per se. I slide the locking collar up the mast 2", then
lock it.
This allows the mast to free float in the lower thrust bearing. I feel more
confident [ and safer] when working on the PP, that the mast is supported
by the top thrust bearing/sleeve/then the lower thrust bearing. [ + the mast is
pinned via the bolt through the sleeve, only used when mast is elevated
a bit, and PP is worked on. I ended up buying the UST mast raising fixture,
which bolts to the 2nd plate [ 6" down from top]. That 2nd plate has
the big hole in it so the cable for the mast raising fixture just passes
through it. A special 2 x piece clamp, clamps to the mast, and terminates
on the
mast lift cable.
## Everything is galvanized, nothing rusts, bearings are built really good,
everything has zerk grease fittings, and the small K7NV PP runs like a
swiss watch, globs of TQ. BTW, you can also get grease fittings that have 90
deg bends in em..and also 45 deg and also 65 deg..and also straight.
I capped off the very top of the 2" x .375" wall chromolly mast. Then no
water coming down the inside of the mast. The mast is also climbable.
I gave up years ago with painting masts. On the galvanized chromolly mast....
I gave it a couple of coats of cold galvanize spray. That stuff is
cheap, and works good. I have enough zinc on everything so nothing should
rust. The cold galvanize spray sticks to the hot dipped galvanized
parts very well.
later....... Jim VE7RF
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|