Quote:
Originally Posted by Tony Wheeler
I'm pretty sure you're not supposed to hang off the end of the handle with your feet kicking wildly in the air trying to turn it!
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Upon reflection my own winch cannot be considered indicative, because the cable drags on the crossbar due to poor installation. This would greatly increase the handle force required, particularly with heavier loads.
For a proper installation we can calculate the handle force required from the gearing (24.5:1 reduction in low ratio) and the mechanical advantage provided by the crank handle radius (485mm for the Dawn handle) relative to the cable winding radius (approx 50 - 150mm depending on how much cable is wound on the drum). For a 2 ton lift this works out to between 19 and 57 lbs. A standard two gallon plastic bucket of water weighs 20 lbs, which means that for the first layer of cable on the drum you could lift 2 tons easily with only one hand, using only the force required to lift a bucket of water. Even with the drum fully wound you could comfortably exert 3 times that force using two hands. If you really put your back into it you could probably manage 100 lbs, which would lift 3.5 tons with the cable drum full, or 10 tons with the cable drum empty. For someone of my weight (approx 85 kg) you would only need to hang off the handle if you were lifting 7 tons with the cable drum full, or 20 tons if it were empty. Based on these calculations you could reasonably rate this winch at 3 tons, requiring 57 lbs handle force, ie. 3 buckets of water, with the cable drum half-full.
We can perform a similar calculation for the Dawn No. 2 winch on the jeep. While it appears to be identical to my Dawn No.5 winch, closer inspection reveals it to be considerably smaller, the only common part being the pinion gear. As a double reduction winch the relative size of the larger gears indicates a ratio of around 16:1 on this unit, which being approx 2/3rds of the No.5 ratio would lead to a rating of 2 tons instead of 3 tons.
Irrespective of any nominal rating it's the wrong choice for the jeep application in my view, being far too low geared.
