Photos needed. Shed full of S**t Auction

[Tony Wheeler]

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!

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.

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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.

dawn-1 - Copy.jpg

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[Tony Wheeler]

Originally Posted by Tony Wheeler

Irrespective of any nominal rating it's the wrong choice for the jeep application in my view, being far too low geared.

Having just seen this pic of the Dawn No.2 winch drum bare of cable I may need to reconsider, as the inner diameter appears to be considerably larger than the No.5 drum on which my calculations are based. This would improve the situation although I suspect it was still geared overly low for the required purpose.

jeep0041.jpg

[David Dunlop]

Not to detract from this thread, Tony, but what is the purpose of the metal boxes covering the front bumper mounting points? Never seen that setup before. Part of the winch kit perhaps?


David

[Lynn Eades]

David, I would suggest a bumper extention as the winch mount sticks out forward of the bumper.
Interestingly this is a slat grill (first 10,000 and all of course were on Willys Chassis)
That the guard is already damaged and that there is a sheet of mesh in front of the radiator.
There is a hook on the front bumper, that I would guess is for a 2:1 pull.
(rope eye back onto the Jeep?)
I see also that the park light has been moved and that the bonnet is unbolted and sitting forward.

[Mike Cecil]

This is an image of the early trials/test mounting. It was not how the design ended up. The extensions were indeed part of the early winch kit development, and because the test mounting protruded forward of the bumper.

The final mounting sat further back, and had a slat cut from the grill to accommodate this, as is visible in the early image posted on the thread, showing a jeep of the 24 Infantry Brigade HQ, 9th Infantry Division, with what looks like a Japanese officer in the back: possibly taking the surrender in British Borneo? Nice image.

Mike C