Having three crank-up towers here and just about ready to install one of the
original HDX-689 crank-up's (Waiting for the foundation to cure), what gear box
is recommended for this type of use?
I have an HDX-572 that has a hub city gearbox and a bit concerned now.
What alternatives are there?
From: TowerTalk [mailto:email@example.com] On Behalf Of Dino
Sent: Saturday, October 13, 2012 7:17 AM
Subject: [TowerTalk] Yet another worm gear box failure...
A couple of years ago I replaced K6CF's US Tower 72' tower with a new HDX
series for this very same reason Mike's failed below... The main shaft going
into the gearbox snapped allowing the pulley to release all tension on the
cables. It was a free fall after that! Both Chris' and Mike's failures happened
while in transit! CHECK OUT THE SOLID SHAFT NEXT TO WHERE THE PULLEY IS
MOUNTED! ESPECIALLY IF THE PULLEY IS NOT SUPPORTED ON THE FREE END! There is a
lot of torque pulling up by the cables!
I've mentioned before about an unrelated Hub City gearbox failure that happened
to me. This failure happened during transit. AA6PW's Fulton brake winch failed
during transit as well! We replaced that with a Fulton K2500 winch...
While I'm a BIG FAN of crank up towers, all these failures are in the front of
my mind whenever I operate them! During transit on an unknown tower I like to
throw a 4x4 in the rungs just in case something cuts loose. I throw the 4x4 in
a coule of feet below the second tower section and bring it down. Then I stop,
pull it out and move it down a couple of feet or rungs. Rinse and repeat until
the tower is down or UP! This way the drop is minimized and so is the damage! A
W-51 I've taken down recently is a good example of this! I had no idea of the
reliability of the brake winch so took precautions. This winch and cables will
be replaced before I sell it!
So people, check out your winch systems carefully! Take precautions during
transit! Keep arms clear! If you have a Hub City gearbox, Hub City recommends
Mobil SHC-630/SHC-634 50/50 mix. Change your oil! Make sure it is full!
As a note, the gearbox failure I witnessed has the worm gear ON TOP of the
case. I saw an older Triex tower where the gearbox was mounted upside down
(worm gear was on the bottom). With the gear on the bottom, it is ALWAYS in oil
and therefore should not rust. The failure I saw was caused by a rusty steel
worm gear taking out the softer bronze gear. Had this gear box been maintained
properly, this failure may not of happened!
Here is Mike's story...
"From Mike's Shack - (2012-10-12 at 3:30pm) SUNDAY, OCT 6, ABOUT 5 PM. AFTER A
LONG DAY’S WORK DOING MAINTENANCE, ON THE WAY BACK UP TO 70 FT, THE 1” SHAFT
FROM THE MAIN WORMDRIVE FRACTURED ALLOWING THE BIG PULLEY TO LET THE TOWER FALL
FROM ABOUT 15 FEET UP. NOT PRETTY. I HAVE LOTS MORE PHOTOS BUT THIS ONE PRETTY
WELL SAYS IT ALL!"
Dino - KX6D
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