Tuesday, 11 March 2014

Mini mechanical advantage system

Can you guess what it is yet?

I've mentioned in previous posts how I've been playing around with a few ideas for tensioning the rigging line. I was looking for several things: something simple that could be taught in a few minutes that was also fairly idiot proof, something that was easily installed and not too gear intensive, I wanted at least a 3:1 mechanical advantage (MA) and I wanted to avoid having to use knots to attach it to the rigging line.

This has yet to be used in anger and only played about with in my workshop so you'll have to excuse the pictures.

So if you assume the rigging line has been set as normal and the end your looking at here is coming down from the tree to the protawrap/bollard.

The rope grab is attached to the line with the MA system already in place
The other end of the MA systems clips into the top of the porty/bollard

Then by pulling on the working end of the MA system tension is applied to the rigging line, with progress being captured on the porty/bollard

Once the MA system is out of room the rigging line can be tied off
A few wraps and a couple of half hitches usually does the trick

And if needed the MA system can be advanced up the line again to add more tension/pull the line further.

When not needed or once the line has been tensioned sufficiently the rope grab is removed from the rigging line and clips into a stein mounting strap installed well above the bollard, the other end of the MA system can be left in place for the duration and everything is ready for when MA is needed again.
So this is by no means the best explanation but I hope you get the general idea. everything is pre tied and set and gets put away as in the top picture. So when your setting up first thing all you need to do is install the stein mounting strap, clip the rope grab end to it, and the other end clips into the bollard and then its all ready to be used as and when needed.
I'm going to try and get a video of it in use as I feel this will help a lot with the explanation!
Any thoughts or queries?


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