Timber said:
For every 15* of angle upwards add 25% to the loaded weight of the object (and this is IF there's no additional resistance). By the time you get to 90*, you're looking at 150% of the object's weight (I believe due to gravity, but don't quote me here).
Great information here:
http://www.pirate4x4.com/tech/billavista/Recovery/index.html
Wow!
So I weigh more when standing on a slope then I do hanging from a rope.
Hey I'm a poet and I didn't even know it.
There's something horribly, horribly wrong with this math.
As in it's completely wrong.
For pulling a load up a slope you use Sin(slope angle in degrees)*Dead Weight Load + rolling resistance.
Sin(slope) will ALWAYS < 1.0, so it can never be equal to an amount greater than the dead weight load itself. The sin(90) {ie; a vertical 'slope'} is equal to 1.0.
Rolling resistance is also a function of the dead weight load, slope and some impossible to determine coefficient of friction.
Normally friction factors are less than 1.0, but the impossible to determine coefficient of friction for being hopelessly stuck in mud could 'effectively' exceed 1.0 resulting in the "friction" component of the equation actually exceeding the vehicle weight.
Of course all of this is foolishly academic and pointlessly worthless.
Bottom line is a 9000 lb winch can pull, drag, lift, hoist, yank, suck or tug 9000lbs. How you achieve that 9000lbs is up to you, but it weighs the same no matter what.
A winch rating implies it's maximum load rating just prior to stall on the last full wrap of cable on the spool. For each additional layer of cable wrap on the spool, the max load to stall decreases.