On 2/3/14 7:14 AM, Mike Reublin NF4L wrote:
Great Jim, thanks!
Lets say 1200 lbs., length of 32' including mast.
So 1200 x 32 / 10 = 3840.
Cos(0) = 1, sin(45) = .707
3840 x 1/.707 = 5430 lbs. initial pull, correct?
Halving that with a 2:1 pulley system = 2715 lbs., a bit over the winch rating.
A 3:1 pulley arrangement drops it to 1810. Do-able but close to the edge.
Mike NF4L
Sounds about right.
Bear in mind that every pass over a pulley adds some drag, not so much
from the pulley bearing (which is negligible with ball bearings) but
from the flexing of the cable.
What's the winch rating? And is that with empty or full cable drum?
These little details often don't show up in the descriptive copy... but
as cable piles up on the drum it increases the effective diameter of the
drum, reducing the maximum pull force. Manufacturers like to give
specs with the drum empty (all the cable pulled out). For a small winch
with a 2-3" diameter drum, that fills up to 4-6" when full, that's a 2:1
difference in pull force.
Does the winch have a ratchet or self braking scheme to prevent it from
freewheeling and paying out the cable if you lose power? (e.g. when the
circuit breaker trips)
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