Pendulum rigging

[Pete Mctree]

Use the Gcrs as a winch to apply the tension to the line.

 

Where in the system whould you put the dynometer?

[rbtree]

I meant trig, not trip function calc's.....

[rbtree]

Use the Gcrs as a winch to apply the tension to the line.

 

Read my post....

[Angus]

Dad still talks about his 2002 ISA adventures with you rb!

In regards to the GRCS, you've summed it up quite concisely rb, but this isn't the first time we've been asked about using a lowering/winching device instead of two separate devices - So I'll have a crack at going through it...

 

I actually gave Graeme a shout about this GRCS thing... he's down at the holiday house, having a fair crack at the prawn population. Damn him.

 

Graeme acknowledged that the GRCS, had it been invented (not that capstan winches are a new thing...), could have been manipulated and adapted the the job. However it would be an inappropriate use of tools available, and the advantages trivial.

 

I've shortened down a few of the key points he had.

 

In Australia, the GRCS is a $4000 lowering device. For one.

The 3/4ton winches were $700. For both.

 

The GRCS is NOT an inline friction device, and is not designed to be loaded sideways.

At some point before you lower, you must remove the dyno from the system.

1. If you are using a GRCS correctly - your rope will be above you, rather than sideways to a pulley (see top-view diagram in the article).

2. If you are using the GRCS as a winch - you'll need to transfer to another mechanism in order to drop the tension enough to remove the dyno. Add more money for another "mechanism" + the fact that the dual purpose device has now become a single purpose device.

 

The steps required in this system to:

1. Attach Dyno

2. Tension

3. Lower

 

Are not decreased by the use of a GRCS, in fact they are increased. Worse still, the device that ideally tensions AND lowers can only do one function, at ten times the price!

 

FWIW, we used 'goldtails' as our friction device.

 

Perhaps if I've misunderstood the application of the GRCS that was being proposed?

 

well, the version of it that ran in a US arb publication anyhow

Do you remember which publication it was?

 

We've just got another job in the same place, but this time we have no practical highpoints that are within ~180o of each other. (a critical precondition to opposing pendulums.)

As part of the solution we've taken opposing pendulums to the next level. A few weeks ago I derived the formula for a triple point lowering system.

I've written and tested the formula AND program, and we're now eagerly waiting to test it out on the job.

The applications of the triple point lowering system are very exciting - far beyond this one job.

 

For example, any job where there are is at least ONE high point can use the program. (The other two can be on the ground, to a car, etc.)

This would give crane level accuracy for significantly less cost.

The highpoints can be at any angle from each other.

The formula can tell you how much tension is on each line, and each highpoint.

 

I've written the program as a graphical windows application, but I'll probably code it for a mobile phone fairly soon.

 

We'll hopefully have a video of the system in action some time in 2010.

[Stephen Blair]

you guys certainly know your stuff, are you needing to find new techniques for tall gums in delicate work sites? it is very hard to get scale from pics and videos but i take it you guys are tickiling the clouds a lot:thumbup1:

[Angus]

Yes is the short answer. We need new techniques and tools to work in some of our sites, and that is a motivator for developing them.

This motivation applies to our whole industry! The tools available to tree workers has been snow-balling for the last few years.

 

The effort required to develop a triple point lowering system hasn't been required by us until now. Since creating this system, I can see the day-to-day benefits it may give us.

The preconditions are a lot more flexible than opposing pendulums, and it will be interesting to see how the system fairs in the real world.

[Stephen Blair]

do you think it could get to the stage where these techniques ar just getting used because they can? or are they actually beneficial? I am just a hick tree climber from scotland who probably couldnt walk in graemes shadow, but when i look at diferent techniques and work out how much time it takes to set up and all the extra staff required, i usually just end up climbing up, takinhg a deep breath and cut n chuck. Are you finding that the success of your business and demand for your level of skill opens the doors to bigger budgets for jobs allowing the extra time spent. I can only imagine some of the stuff graeme has pulled off in his day before health and safety got its foot in the door lol:thumbup1:

 

I am not being cheeky or trying not to be critical, i am just really interested mate:001_smile:

 

and with a name like angus you must have some scottish roots:biggrin:

[Angus]

Who would I be to pass judgement - I'm still on my climbing learner plates!

I can only speak for my small pond, but there does seem to be a growing tendency amongst climbers coming from arboriculture courses to overcomplicate simple jobs with advanced rigging and access techniques. That could be a whole other thread...

 

Are you finding that the success of your business and demand for your level of skill opens the doors to bigger budgets for jobs allowing the extra time spent.

Practical and academic pursuits meet in an unusual mix in the tree industry. So far as I can tell, there has always been a need for professional tree workers which can safely adapt a variety of techniques to remove tree's in a safe manner.

The rigging we're talking about addresses a very specific set of job conditions, where absolute control is the highest priority.

 

I think we must have some sort of scottish roots with names like Angus, Keely, Allister and Lachlan! Irish too... (Don't judge me for it)

Edited December 30, 2009 by Angus

[Stephen Blair]

thanks for the reply mate, i feel really chuffed that i can talk to you. its a real treat for me sitting in my wee house talking to someone at the other side of the world, i love this place..how do you guys get on with snales and beasties, how do you clear a site of them or minimise the risk??

[Will Hinchliffe]

Can you eliminate the need for a dynometer in a system like this by taking the pieces off with a step cut at 90 degrees to one of lines then tensioning 1 line to lift the piece.

 

Im just throwing ideas about.