 | Home > Technical > Winching: theory vs real life |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17606   
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My bad, I should have expressed myself more clearly!
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15th Jan 2015 6:46pm |
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| Supacat Member Since: 16 Oct 2012 Location: West Yorkshire Posts: 11018 
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Is that how they are supposed to be used 
https://www.youtube.com/watch?v=81VyT87aK5Y |
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15th Jan 2015 9:54pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17606
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It's certainly how they've been marketed for years, and yes, you can uproot trees up to a metre diameter or so with one.
I have heard that much of Africa's deforestation was done with Trewhella monkey winches! The Wallaby is a slightly smaller and much more sophisticated version of the monkey winch (and also very scarce second-hand and expensive). |
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15th Jan 2015 11:11pm |
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| Chris86 Member Since: 15 Jul 2014 Location: South Yorks Posts: 795 
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I have found it quite scary on occasion watching winching and also rope hauling through my work, seeing the ignorance about the potential to collapse a hauling system.
The question is, where is the weakest point in the system? Is it the winches attachment point to the vehicle? Is it the winch cable/rope (with a dyneema type rope then if its going over any sharp edge or abrading on itself then the answer is yes!)? Is it your attachment point to your anchor point (have you maintained a rigging angle of less than 90 deg?) Is the pulley up to the job or simply introducing more friction? When teaching swiftwater rescue courses we do quite a lot of rope hauling to release trapped boats, casualties, vehicles etc and the key things that are forgotten (in my experience) are; Direction of Pull and Friction! Conversely with winching how often do you see a vehicle being winched with a poor direction of pull, or simply being winched further into/onto the obstacle that has caused it to get stuck in the first place? I have rarely had cause you use the winch on my 110 but would sooner extend out using strops and do a pair of twin line pulls (2:1) than a single line pull over a longer distance. Chris |
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22nd Jan 2015 2:55pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8171  
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i catn quote, but your last para does bring in more items that could fail into the equation but i understand the thought process Cheers
James 110 2010 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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22nd Jan 2015 8:22pm |
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| Chris86 Member Since: 15 Jul 2014 Location: South Yorks Posts: 795
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Quite true!
Its all about making an educated decision based on an understanding of the parts of the system. I base my comment on reducing the amount of 'work' the winch has to do, knowing everything else is within its limits! Chris |
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22nd Jan 2015 9:37pm |
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| zone30 Member Since: 07 Sep 2012 Location: Gent Posts: 669  
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In that regard, what should be the weakest point for it to fail safely? Winch motor?
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23rd Jan 2015 2:48pm |
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| Chris86 Member Since: 15 Jul 2014 Location: South Yorks Posts: 795
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If the winch just 'stopped' then I suppose yes?
Elsewhere in the system it would depend on a number of things, the main one being cable or synthetic rope. Synthetic ropes tend to dissipate their energy in a fairly controlled fashion (they are essentially a semi-static rope- low stretch) and weigh relatively little, wire cables stretch build up energy before breaking and are heavy! A few years ago I was stood nearby when an attachment to a pontoon with a tirfor attached under tension snapped- scared the S%1t out of me! I have yet to see a shackle fail catastrophically, the ones I have seen fail have just been rendered unusable by being deformed (Ford county forestry tractor......)- however that isn't to say that they do not fail! Probably the 'best' answer is anywhere where there isn't the potential for flying metal objects! 
Chris |
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23rd Jan 2015 3:05pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17606
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Manage your failure mode by including a component which you know to be the weak link in a position where either failure doesn't matter, or the consequences can be contained.
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23rd Jan 2015 4:22pm |
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