Discovery Rust - Boot, Sills and Wings

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Here's a chart on percentages of pull vs bridle angle


Angle % ratio Angle % ratio Angle % ratio
0° 50.0 65° 59.3 130° 118.3
5° 50.1 70° 61.0 135° 130.6
10° 50.2 75° 63.0 140° 146.2
15° 50.4 80° 65.3 145° 166.8
20° 50.8 85° 67.8 150° 193.2
25° 51.2 90° 70.7 155° 231.0
30° 51.8 95° 74.0 160° 287.9
35° 52.4 100° 77.8 165° 383.1
40° 53.2 105° 82.1 170° 573.7
45° 54.1 110° 87.2 175° 1146.9
50° 55.2 115° 93.1 180° ∞
55° 56.4 120° 100.0
60° 57.7 125° 108.9
 
SNATCH BLOCKS AND THEIR USE

So ideally the line of pull on a winch should always be straight ahead as that ensures that the winch wire does not gather on one side of the drum and naturally spools up neat and tidy.

The image below shows snatch blocks and their relative ratios

2351790904ffd12399a5696e2fa8ceba.jpg


1:1 or direct/redirected pull.

Using a snatch block to redirect the pull direction is useful if you have another vehicle to anchor to but it is at 90 degrees to you. Despite the redirection of the winch line you are still getting a direct 1:1 pull.

2:1 Ratio

Here you are stuck deep in mud upto the axles and you need to make sure that you are not going to cook the winch.

By using this set up you make the winch work less hard to pull a given weight but you also half the speed in with which your winch retrieves its cable.

Effectively the force of the pull is halved between the two cable runs.

3:1 Ratio

Here the cable is fed through two snatch blocks so the force is shared between 3 lengths of cable effectively dividing the force by 3 hence 3:1.

This in turn also reduces the winch speed of cable retrieval to one third it's normal speed.


You can also use snatch blocks to winch yourself backwards with a forward winch, winch yourself sideways to clear obstructions plus all other manner of things.
 
had unexpected visitors, apologies for the absence!
was rather meaning the forces exerted when using 2:1's and inderect pulling, in relation to the anchors involved and extracting dead objects. ie the force exerted on an anchor or vehicle where a snatch block is placed mid rope, giving a degree similar to that of a tight bridle, in the region of 120 - 170 degrees.
however, i'm impressed with your diagrams and they convey more information than words could ever do. i would have to resort to drawing on paper and scanning, then posting as a piccy!
 
Ok I understand, I will try and get some time to answer that as it is interesting, but difficult to explain. It's been a while since I had to use any of my HND in civil engineering lol.
 
gummy bear said:
Right,come on then.christmas is done,back to it ; )
Click to expand...

Very funny......

Been messing with camera mounts for my action cam and a handycam. Unfortunately the codecs that the action cam use aren't compatible with windows 7 and the handycam quality is below par and much worse than my iphone4s.

I have got quotes on some metal work for some suspension and protection equipment but nothing moving on that at the moment.

I do need to mount the laptop now as that is carrying the maps but it can allow wait until the MOT which is due Wednesday.
 
Yeah the GreenHornet has passed the MOT once again!!!!!!!!!! Howev this summer will see a new windscreen as mine has a chip in it, and a bit of corrosion on the rear body mount before it gets bad.

Now what shall I do next...............
 
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