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Castor Dolly For 30 CWT Truck - Checking the Mathematics
Hello All,
I would like to make a set of cast iron castor-based dolly stands to be able to move my 1940 MCP Chevrolet 30 CWT truck around in my shed. The truck is missing its manufacturer's Specification Plate that says what the carrying capacity and other weights like Gross Vehicle Mass or TARE are. At the moment I can only work off the truck once being identified by another truck owner of the same size as a 30 CWT truck. Do the following calculations sound okay strength wise? The type of arrangement I am thinking of building appears in the attached photo. I would be using stronger materials to build the dolly. There are 100 mm cast iron castors that are rated at 225 Kilograms per wheel The truck is rated at 30 CWT or 1.5 Metric Tonnes or 1.68 US Ton (short) or 1.49 Imperial Ton (Long). Does this mean that each of the truck's wheels would bear the weight of 375 Kilograms - fully loaded? --------------------------------------------------------------------------------------------------------------------------------------- If a single castor is rated at 225 Kilograms and a dolly is made up of four castors - does this mean the carrying capacity of the dolly is 225 x 4 = 900 kilograms? ------------------------------------------------------------------------------------------------------------------------------------- I figure working off the truck's carrying capacity instead of its TARE would provide me with a large built-in safety margin to work within. Is this thinking that four castors 225 Kilogram rated castors on one dolly multiplies the capacity of the dolly at 900 Kilogram correct or false? Also, is the thought that dividing a truck's carrying capacity by four tyres is correct or false? ---------------------------------------------------------------------------------------------------------------------------------------- The reason I choose to use cast iron castors is that if they sit in the same position for a long time they should not develop flat spots. I built a timber engine dolly for a 216 Chevrolet motor where I used polymer based wheels. Over a period of time with the engine sitting in one place the wheels had developed flat-spots. What wall size square hollow section and rectangular hollow section would be the most suitable? Kind regards Lionel
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1940 Chevrolet MCP with Holden Built Cab (30 CWT). 1935 REO Speed Wagon. 1963 Series 2A Army Ambulance ARN 112-211 Series III ex-Military Land Rovers x 2 Last edited by Lionelgee; 13-08-20 at 07:34. |
#2
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Lionel, I have copied a page from Wheels & Tracks magazine no.8 with technical details of the 1940 Chevrolet WA, including weights.
See http://www.mapleleafup.net/forums/sh...530#post271530
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Regards, Hanno -------------------------- |
#3
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Quote:
Thank you for the reproduction of the page with the data about the 30 CWT 1940 Chevrolet. It is very greatly appreciated. Just wondering - the truck shown has a single wheel rear axle. Did these 30 CWT trucks come with an option of dual rear wheels? My truck still has the white paint on the differential cover and its body colour is described from the factory as "Khaki". The front mudguards were also bikini-ed slightly to provide more clearance. I have to measure the wheelbase again. I once wrote it down however that piece of paper has been mislaid. Kind regards Lionel
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1940 Chevrolet MCP with Holden Built Cab (30 CWT). 1935 REO Speed Wagon. 1963 Series 2A Army Ambulance ARN 112-211 Series III ex-Military Land Rovers x 2 |
#4
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Lionel,
I know that this is covered by Hanno's post but in WW2 a truck was specified by its carrying capacity not its unladen or gross weight. A 30cwt truck would carry 1.5 tons but probably have an unladen weight of about 2.5 tons or even more if 4x4. If empty there would be rather more than half the weight on the front axle so say 0.75 ton per wheel. If the front were supported by two dollies, each with four castors, each castor is supporting nearly 0.2 ton. However, if you are pushing the truck and a castor meets an obstruction, say a bit of rubbish or a ridge in the floor, the load on it could easily double. The bigger diameter the castor wheels are the better in terms of climbing obstructions and of course it will be much easier to push with bigger castor wheels but cost will be a big driver here. If you have dead smooth concrete I would tend to not worry too much and use the 225kg castors but if the concrete has ridges in it left from tamping it, bigger castors might be worth it. I agree about polymer tires getting flats. I would probably make the dolly frame out of 50 x 50 x 4 mm or 40 x 40 x 5 mm square tube. Both are very easy to get here but possibly not where you are. I prefer tube as it is much more rigid than angle for a given weight. I would just make a rectangular frame, say 500mm x 400mm and bolt the castors onto the corners. A truck wheel would sit directly inside the frame or you could put timber on top and sit an axle on that, possibly with a ratchet strap to stop it falling off. I think that you would be amazed at how much use the dollies get for all sorts of jobs. David |
#5
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With respect to capacity of caters, if you want to be very conservative, work from gross weight. Otherwise go with the empty weight of the truck. The carrying capacity of the truck (30 cwt) isn't very relevant to the casters as there won't be cargo in the truck while on casters.
If you have 4 dolly stands (one at each corner) and each one has 4 casters, and if you assume that all corners of the truck weigh the same (probably a bad assumption), each caster should carry 1/16th of the weight of the truck. Perhaps this will strike you as picky but 30 cwt is exactly 1.5 Imperial/long tons (since a long ton is 20 cwt, and each cwt = 112 pounds). 30 cwt in any other system will be the result of conversions to that system. 30 cwt = 1.524 tonne = 1.68 ton (short). The diagram on the right in Hanno's post shows both single and dual wheels (each setup on one side of the truck) which suggests there may have been a choice (unless they were using a generic diagram). |
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Quote:
Hmmm, I missed the bottom line of the diagram. I grabbed a copy of the image and took it over to "Paint" and magnified it... Yes it does clearly say "dual". I went through some of my old posts because I thought I had written down the wheelbase measurement beforehand. Due to my lack of success I will measure it again tomorrow once it is light enough. I just bought a copy of the 1942 Chevrolet 4 x 3 1.5 Ton Truck Maintenance Manual for Right Hand Drive on eBay. I realise that it is the model after my truck and a Lend Lease type. However, the manual will fill in some missing gaps of knowledge about my truck. At least it looks like my truck in the attached photograph. There is also an Australian Parts Manual by a company starting with "N" that Mike Kelly once mentioned being worthwhile to get. NAPCO or NASCO? Kind regards Lionel
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1940 Chevrolet MCP with Holden Built Cab (30 CWT). 1935 REO Speed Wagon. 1963 Series 2A Army Ambulance ARN 112-211 Series III ex-Military Land Rovers x 2 Last edited by Lionelgee; 13-08-20 at 15:37. |
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Almost guaranteed NASCO for National Automotive Service Co. which is clearly associated to General Motors Holden's Ltd.
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#8
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www.gmheritagecenter.com
Quote:
When determining the details of the Indian Pattern Chevrolet 1311X3, I found the GM resource linked below very useful to look up wheelbases, tyre options and other specifications. Quote:
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Regards, Hanno -------------------------- |
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Hello David,
Thank you for your insight and for the suggested dimensions. It gives me a better idea of what I will have to plan for. Kind regards Lionel
__________________
1940 Chevrolet MCP with Holden Built Cab (30 CWT). 1935 REO Speed Wagon. 1963 Series 2A Army Ambulance ARN 112-211 Series III ex-Military Land Rovers x 2 |
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Hello All,
I found a transcript of a Manufacturer's Plate that may have been off my truck. It was written down years ago along with the plates from other trucks I found in a truck parts yard 5 hours drive from home. So the following transcript might not be the right one. Anyway - do the following figures sound correct? Apologies for the following all caps... CHASSIS: 5200 MAXIMUM WEIGHT IN POUNDS: 3400 ?? GROSS WEIGHT: see note 11500 MAXIMUM ALLOWABLE GROSS WEIGHT INCLUDES CHASSIS BODY AND ALL LOADS AND IS SUBJECT TO THE UNIT BEING EQUIPPED WITH WHEEL AND TYRE EQUIPMENT OF ADEQUATE CARRYING CAPACITY I am not sure what the Chassis 5200 refers to? The writing after Maximum Weight in Pounds of 3400 was illegible - any idea what it may have been? According to an online conversion 3400 Pounds equals 1.5178571428571428 Long Tons or 1.5 Ton... so a 30 CWT carrying capacity. The Gross Weight of 11500 pounds according to the same converter is 5.133928571428571 Long Ton. I wonder if I wrote poundage down correctly at the time? It is a shame that the plate did not mention TARE or Curb Weight. Kind regards Lionel
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1940 Chevrolet MCP with Holden Built Cab (30 CWT). 1935 REO Speed Wagon. 1963 Series 2A Army Ambulance ARN 112-211 Series III ex-Military Land Rovers x 2 |
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