The CMP was rated as a 3 tonner while the Jimmy only 2.5 (Deuce and a half). The Jimmy is a much larger vehicle with three axles and ten wheels vs 4 wheels on the CMP. Jimmy's GMC 270 engine was a slightly larger version of the CMP Chevy 216 and also a bit bigger that the CMP Ford V8. Could the CMP really carry a heavier load than the GMC? This shot of heavily laden Jimmys has always impressed me.
Isn't the Jimmy's 2.5 capacity rated as 'rough terrain'? Sure it was rated at twice that over better surfaces. (Not sure why I'm sure...) Not that that means the CMPs weren't rated in the same way. Jimmy's are quite 'skinny' when you see them in the flesh. The Bigger CMPs quite chunky.
Yes, GMC 2.5 ton was rated at 5 tons on roads. Some were built for road use only and lacked the driven front axle. Mike
There's a part of me that only initially thinks of 15CWT, FAT, Quad etc. when someone says 'CMP'. 3 Tonners are substantial lorries, lurking behind that familiar style cab. None of which answers the specific load ratings query for them & Jimmys... Might have a look in W&T. Unless someone who knows the area better potters along.
At this moment in time I have not found out why these trucks were rated/classed/called three tonners 2.5s ect. Unless the truck classes at the time were, 15 cwt, 3 ton, 5 ton, 7 ton, and so on. Then that would be the class they were in although some would carry less and some more than 3 tons, but not enough to fit in the other classes. However to determine what load a truck can carry safely and economically is down to a lot of factors. Size of engine, Space for cargo, number and spacing of axles, type of suspension, tyres etc. So manufactures will give a gross weight at which they consider the maximum weight that truck can work at safely and economically. They will also give the kerb or tare weight of the truck. Which is the weight of the truck empty, no weight of the driver, his packed lunch, fuel etc is considered in this. 2240 lbs = 1 ton. 3 tons = 6720 lbs. 5 tons = 11200 lbs. So looking at the GMC its weights are. Gross Wt. 16400. Tare wt. 8800. Cargo wt. = 7600 lbs https://en.wikipedia.org/wiki/GMC_CCKW_2%C2%BD-ton_6x6_truck CMP. C15. Gross wt. 11200. Tare wt. 4800. Cargo wt. = 6395 lbs. http://www.mapleleafup.net/vehicles/softskin/chevspec.html This shot of heavily laden Jimmy’s has always impressed me. Now with the above and below information will you be so impressed by the Jimmy’s? A rough estimation there are 400 cans on the truck 1 jerry can empty = 10.5 lbs. Full = 41 lbs 400 x 41 = 16400 lbs. more than double the weight the Jimmy was supposed to carry. Yet there is no indication that the suspension is low or the tyre’s are bulging. I would guess they are empty also by the way there are loaded on the other truck. 400 x 10.5 lbs = 4200 lbs well within the limit.
That makes sense. It hadn't occurred to me that the cans might be empty. Still like the picture though Here is a nice home movie of an American truck assembly line in France for GMCs. I saw a somewhat similar one from Australia a long time ago but I can't find it again. The Aussie one was more official and showed an Australian government facility that dissembled war weary jeeps and Dodge WCs down to the last nut and bolt and then rebuild all the components into new condition and then reassembled and repainted the vehicles. It was a really good movie. Anyone have a link to it?
I see that no one has remarked on the difference between the American (short) ton of 2000 lbs and the British/Canadian ton of 2240 lbs. The weight description of army vehicles normally refers to the load capacity cross country, but when there's a war on I suspect that such limitations are largely ignored. I would assume that, for instance, a three ton truck would be built as a manufacturer's reponse to a governmant specification requiring that the thing could carry a three ton load cross country without undue strain. Not that weight classifications are set in concrete. Not that long after WW2, three tonners in the British Army were reclassified as four tonners, and 15 cwts as one tonners! Chris
