[UK-CONTEST] Gin Pole Pulley system

[Cooper, Stewart]

Just to clarify what you see in the last picture (which is 20 years old) of the 4 yagi portable lifting arrangement (not the 80m vertical). The person is cranking the winch around which the up-haul is attached. The winch is bolted to the 'gin pole'. This arrangement is way too heavy to just haul up by hand - now that would be impossible! The 'guys' are steel wire and the guy pins are 3ft long.
Allan GM4ZUK uses an identical arrangement with a 50ft x 2.5" diam mast and 4 Cushcraft 2m yagis. I also use it for the C3S in Shetland.
It's portable and indestructable!
 
Stewart
 
Stewart Cooper
Maintenance Systems Engineer

ODL
Buchanan House  Summer Street  Aberdeen  UK  AB10 1SJ

Tel (Direct) +44 (0)1224 628039
Tel (S'board) +44 (0)1224 628000
Fax +44 (0)1224 643325


________________________________

From: uk-contest-bounces at contesting.com on behalf of Dave Lawley
Sent: Fri 16/11/2007 18:27
To: UK Contest Reflector
Subject: Re: [UK-CONTEST] Gin Pole Pulley system



Have to say the last of Stewart's pictures gives me the horrors! No
useful purpose is served by a person being at the base of the mast, but
if anything breaks then he stands a good chance of being killed or
seriously injured.

The great thing about the gin pole / block & tackle system is that one
person can put up a 70ft mast single handedly, and keep well out of the
danger area.

How you rig the block & tackle depends on how many sheaves there are on
each block, but with two double blocks you need the rope tied to the
upper block, i.e. the one attached to the top of the gin. It's important
to use the correct diameter rope for the sheaves you are using, to
minimise friction. You need as much of your effort as possible to go
into raising (or lowering) the mast. Braided rope is better than laid,
if you do use laid rope make sure you don't end up with the two blocks
twisting relative to one another, which will give you a big friction
problem.

When doing it single handedly it's rather important to have the back
guys tied off! If you're on flat level ground and can arrange the side
and back stakes to be on the same radius then you can measure the back
guys against the side ones and tie off at approximately the right
length. While on the subject, even on level ground the side guys on the
gin can sometimes get very tight so it's as well to start off with them
on the slack side.

When the mast is nearly vertical, you'll probably be a long way out,
having pulled on four times the length of rope compared with the
starting distance between the blocks, so you then need to walk forward
to the gin pole (the end would typically be a few feet above ground) and
then pull in the last few feet of rope and tie off.

Easier to do than explain!

Dave G4BUO



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