Koehring Dumptor "Iron Mule" Rocker Dump Hauler

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This odd haul truck was at one time rather common. It avoids power dumping and hydraulics via a carefully balanced rocker body. You dump it by releasing a latch and stomping on the brakes. After it empties, the balance changes, and the body can return to the latched travel position, with a little help from the brakes. It is basically a large power wheelbarrow. Note that dump uses curved rockers instead of trunnions, with tie rods to keep the bed aligned.
For production hauling, it was hard to beat, if you consider a couple seconds dumping time in the cycle. The very simple design would have been easy to maintain, but hard on your back. Note that the owner added a seat belt, and isn't doing an 8-12 hour shift 6 days a week.
There are movies from the big depression era dam projects of earlier versions dumping over a cliff by slamming into a timber. The front wheels would come off the ground. I wonder how many went over the edge if the latch didn't release.
It is designed to be driven "backward", giving the driver limited forward visibility. Pre-OHSA.
Detroit Diesel, not sure of the size.
Limited references I found indicate that it's 6 yard capacity, and probably pre-1950.
The CAT dozer is a D4.
Detail photos at 9:33.
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2019 Old Construction & Mining Equipment Show,
New Athens Ohio.
September 2019
Panasonic FZ-1000
190907p Dumptor