Castor Dolly For 30 CWT Truck - Checking the Mathematics

[Lionelgee]

Originally Posted by Hanno Spoelstra

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

Hello Hanno,

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

[David Herbert]

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

[Grant Bowker]

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).

[Lionelgee]

Originally Posted by Grant Bowker

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.


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).

Hello Grant,


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

[Grant Bowker]

Originally Posted by Lionelgee

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?

Almost guaranteed NASCO for National Automotive Service Co. which is clearly associated to General Motors Holden's Ltd.

[Grant Bowker]

The problem with tare weight is that it includes both cab and chassis (made by Chevrolet/GM/GMH and body (often made by a separate manufacturer) .
It is easy for the chassis builder to give the weight of their part of the truck, also easy for them to give the gross capacity but less easy for them to give tare which is only known after the body is fitted, often by someone else. That said, there was a period when Ford and Chevrolet did sell complete trucks (dump, stake, platform etc.) and I don't know if the weight tags for those vehicles would have shown tare or if the same blank tags were used for all trucks, complete or not...

[Lionelgee]

Hello All,


I measured the wheel base and it is 159 inches. The front spring hanger is broken so the axle is skewed. This means the measurement I took is only approximate.

I also just found Mike Kelly's posting from the 04-04-16, at 01:55 accessed from http://www.mapleleafup.net/forums/sh...21&postcount=5

Mike wrote:

I have the 1940 GMH NASCO parts book . The front cover of the book states "SPECIALLY COMPILED FOR THE AUSTRALIAN COMMONWEALTH MILITARY FORCES" . The book is for sedans and trucks

The 1940 Chevrolet truck was series 13, 14, 15. The model 15 was 158 1/2" wheelbase ( yours ? )

With my measurement of 159 inches; and Mike saying the model 15 had a wheel base of 158.5 inches, it matches my truck being a 15-40 E2

Mike wrote that the 15-40 E2 has a ... Chassis and cab with special 10ft. 6ins x 7ft GS Wagon with canopy top- Standard truck chassis Dual wheel with 7.20 X 6 pierced disc wheels rear axle ratio 6.166 to 1

One message identified the title of the book I am still trying to track down, and what model my truck is.

Next question... was the 15-40 E2 a 30 CWT or 1.5 ton truck?

Also, some of the Chevrolets had the model "WA". Is this the 1940 model a "WA" Is the use of "WA" an Australia designation or an American one?

My model was only produced from 1939 to 1940, in 1941 the head lights changed to being mounted to the mudguards and the front grille changed from just having horizontal bars to the 1941 having a mixture of horizontal bars on top and vertical bars in a sort of pear-shape.

There was a difference of one horizontal bar in the grille between the 1939 and the 1940 - I cannot remember which year had the most bars? My 1940 Chev has 16 horizontal bars on the grille below the Chevrolet emblem top piece.

Kind regards
Lionel

[Lionelgee]

Hello All,

Going off Mike's measurement for a tray - "Chassis and cab with special 10ft. 6ins x 7ft GS Wagon with canopy top" - it looks like my truck may have had its tray replaced in its civilian life as a farm vehicle.

The truck's current tray is approximately 12 Feet long by 7.5 Feet wide. The measurements are approximate because the sides and ends of the tray are timber and they have rotted or been broken off.

Kind regards
Lionel

[hrpearce]

Next question... was the 15-40 E2 a 30 CWT or 1.5 ton truck?

30 CWT is 1.5 ton.

[Hanno Spoelstra]

Originally Posted by Lionelgee

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?

Lionel,

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.

Originally Posted by Hanno Spoelstra

Sources (accessed 28-apr-2020):
https://www.gmheritagecenter.com/gm-...tion-kits.html