With SAFETY in mind, do not always assume that a worm drive can never be
driven by the load. Not all worm drives are created equally. A low ratio
(15:1 possibly) worm can be driven by the load. I have a couple of them
that I had used as a small winch (drum added) for antenna/tower work until I
discovered this trait first hand. The higher ratio, typically 60:1 worms
and certainly any of the double worms are likely to break something WAY
before they will turn backwards.
73 Don
VE6JY
----- Original Message -----
From: "W1GOR" <W1GOR@Maine.RR.Com>
To: <towertalk@contesting.com>
Sent: Friday, March 21, 2003 09:18
Subject: [TowerTalk] Re: TowerTalk Digest, Vol 3, Issue 36
> Greg,
>
> There seems to be TWO types of winches that are typically supplied with
> towers. One type is designed with SPUR GEARS and is probably the type
that
> caused your injury. The second type is designed with a WORM GEAR and can
> only be driven BY the worm gear. Spur-type winches can be driven TWO
ways,
> either by the winch handle, or, in your case, by the load. Worm-gear
> winches can NOT be driven by the load, since the 'spur gear', the one that
> is driven by the 'worm gear', cannot drive the 'worm'... In this design,
> ONLY the worm can drive the spur gear, but NOT the reverse. Also, the
> worm-gear type of winch CANNOT FREE-WHEEL... It MUST be driven by a crank
> handle, or, if the shaft is 1/2 inch diameter or less, by an electric
drill
> motor...
>
> I've been specifying ONLY worm-gear winches on ANY device that requires a
> winch... Towers, Engine Hoists, and other machines that need the
mechanical
> advantage of a winch. Telescoping towers that use WORM GEAR winches do
not
> require stopping blocks to hold their position. The winch can raise or
> lower the tower to ANY height and KEEP it there by virtue of the worm/spur
> winch.
>
> Never be afraid to try something new.
> Remember, amateurs built the ark,
> professionals built the Titanic...
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