[TowerTalk] Hub city gear box failure on crank up tower?
nv8a at charter.net
Sat Jun 23 10:51:41 PDT 2012
My US Tower HDX-555 -- about six years old -- has this same Hub City
gear box. What is US Tower using now?
The Hub City docs. included with my documentation package from UST
specify SAE 90 or SAE 150 oil depending on the ambient temperature.
As for the intended purpose of this device: wouldn't a conveyor belt run
continuously? For a tower use would be extremely intermittent: my tower
has been raised and lowered only a few times a year.
On 06/23/12 12:09 pm, Dino Darling wrote:
> I do! First hand! Its not fun!
> In my case, I was hired to fix the electric motor, which was sent out to
> a motor mfg authorized repair facility. The motor worked GREAT!.
> The gear box was a 50:1 and HAD a breather on top when new. This
> breather had been missing for many years and covered up with a plastic
> bottle cap in an attempt to keep water out. I told the owner that I was
> not comfortable with the current state of the gear box. We agreed to
> drain the oil out and try to flush the system. This required drilling a
> small hold in the bottom of the bracket to access the allen drain plug.
> The oil that came out was NASTY! I saved it and still have it in a
> bottle to this day! I refilled it with fresh oil and with the drive belt
> disconnected, operated the gear box by hand. I made a few revolutions
> and then drained the new oil out. Rinse and repeat 4 more times. Each
> time I drained the oil out I noticed small bronze flakes. The gear box
> had not been used in over 5-years according to the owner.
> I stated I was still leery about the box but we agreed to give it a go.
> I connected the rebuilt motor and the drive belt and let 'er rip. We
> went up a few feet, stopped, and then down a few feet. All of a sudden
> there was a drop of a few inches. I took this as the cables slipping in
> the tensioner and gave the spring a couple of turns. After a few
> revolutions it slipped again. I said, "lets get this thing on the
> ground!" It was a 72' tower that was probably half way up for the last
> 5+ years.
> As it was coming down it would jump, then come down normally. Again, we
> attributed this to the cables slipping on the tensioner and not a gear
> box failure. Finally the tower spooled down with disastrous results.
> Upon investigation it was discovered that the gearbox input shaft and
> output shaft were no longer connected.
> I removed the motor drive, took it to work and disassembled the gear
> box. All the teeth on the larger BRONZE gear were ripped off and laying
> in the bottom of the case. The smaller STEEL worm gear was rusted from
> being exposed to water for the past 5+ years due to the missing breather
> cap. Unfortunately, you could not inspect this without taking the gear
> box apart. The orientation of this particular gear box had the input
> shaft (steel worm gear) on the top of the case. I've seen other set-ups
> where the orientation has the input shaft on the side. Because the input
> gear was on top, it was exposed first to the elements. The rest of the
> box was flooded with oil, albeit contaminated oil.
> I contacted US Tower and they said they no longer use or support the Hub
> City gear box. So I called Hub City.
> After multiple e-mails back and forth it was realized that the gear box
> is actually a "50:1 W300 Speed Reducer" intended for use on conveyor
> belts, and according to the manufacturer, was NEVER intended to lift
> loads...only slow down output speeds. When I asked for a replacement,
> Hub City was RELUCTANT to even sell me one as they did not want to be
> responsible "when it fails again" when re-installed. Here is the gear
> box... http://www.hubcity-ps.com/index.php?action=model&code=W300
> The oil for these gear boxes, per the manufacturer, is Mobil SHC-630
> (Grainger #6Y778) and SHC-634 (Grainger #4ZF30). The reason for the two
> different oils is their viscosity ratings, which are SAE 90 and SAE 140
> respectfully. Hub City recommended mixing the two to get a viscosity
> around 110. I talked to Mobil directly and they said the oils are
> IDENTICAL except for the viscosity and mixing is not a problem.
> I have detailed pictures of the damaged gear box that I will post on my
> website if requested. Everything was returned to the owner and the tower
> was never repaired due to the enormous cost of doing so. Its my hope
> that someday a used tower can be swapped out to replace the broken one.
> For the good of the community, here are the lessons learned. When the
> tower "jumped" the first time, I should have inserted 2"x4" or 4"x4"
> blocks to limit the fall of the tower should something give way. This
> could have been done safely using a ladder on the outside of the tower
> and inserting the wood between the two lower sections. The gear box
> still would have failed, but it would have prevented the tower from
> collapsing into itself. It should also be noted that this failure was
> inevitable due to the preexisting internal damage of the gear box. If it
> didn't happen while I was there, it would have happened soon afterwards.
> This was my Apollo 13! I am leery of any Hub City control box because of
> this failure and I warn EVERYONE who has one. This is due to the
> Manufacturer of the gear box stating that it was not designed for this
> This is my story...its sad but true...
> Dino - KX6D
> -------- Original Message --------
> Subject: [TowerTalk] Hub city gear box failure on crank up tower?
> From: "Richard (Rick) Karlquist"<richard at karlquist.com>
> Date: Wed, June 20, 2012 2:28 pm
> To: Karyn Kornreich<karynkornreich at yahoo.com>
> Cc: "towertalk at contesting.com"<towertalk at contesting.com>
> Does anyone have any specific knowledge of a Hub-City
> gear box failing? What is the failure mechanism?
> What can be done to prevent it? Is there a better
> gear box to use? Is this something I really need to
> worry about?
> Rick N6RK
> On 5/29/2012 4:11 PM, Karyn Kornreich wrote:
> upon failure of the crank up cable or failure of the lifting
> Hub-City gear box. Upon locking the unit from the ground, a
>> Thank you, Paul Landau
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