I’ve been looking for a winch to pull a full sized truck on to a trailer and came across this excellent formula for figuring out what size is needed. Thanks to Pacific Marine and Industrial for posting these up. I am re-posting here to make sure they aren’t lost.
The 2012 4×4 Ram weighed in at 5700lbs so using the following formula;
5700(.372+.05) = 2405
That is assuming the trailer ramps are about 40 degrees and using the high end of load on wheels value.
Required Line Pull = W(Gr+Cf)
W= Weight
Gr = Grade Resistance
Cf = Coefficient of Friction
They even provided some tables with friction and grade values already populated.
Coefficient of Friction
.40-.60 Steel on Steel
.40-.60 Wood on Concrete
.30-.70 Steel on Concrete
.02-.05 Load on Wheels
.05-.10 Load on RollersGrade Resistance
% Grade GR
5 0.05
10 0.1
20 0.196
30 0.288
40 0.372
50 0.448
60 0.513
70 0.573
80 0.624
90 0.669
100 0.701
200 0.896
400 0.97
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