C30 LAA 12 cab

[Pete Ashby]

Can any one shed any light on this question?
C30 12 cab LAA tractors are not listed as a type in the DND body parts list issued October 1941 revised January 1942.
I know the body type is 7D1 and was used on both 12 and 13 cabs, only being modified to take a spare wheel when R/F tyres were discontinued, but I mystified as to why it is not listed as a body type.

Anyone know why?

Pete

[Dirk Leegwater (RIP)]

Originally posted by Pete Ashby

I know the body type is 7D1 and was used on both 12 and 13 cabs, only being modified to take a spare wheel when R/F tyres were discontinued, but I mystified as to why it is not listed as a body type.

Anyone know why?

Pete, some information from the "Design Records" volume V.

Dirk

http://lwdparts.dominodeveloper.net/.../PeteAshby.jpg

[Pete Ashby]

Dirk

Thank you for the info,

I find the reason stated for up rating the wheel size interesting.

I would have thought that pulling a Bofors gun would have favoured lower ratios i.e. 30/60cwt diffs and smaller wheels. Improved road speed with lower transmission/engine stress would not I would have thought been an issue here, can anyone shed some more light on this?

As you know the Oxford crew run two 30cwts on 1050.16's, the C30 11 of Steve Stone and the C30 13 LAA of Keith Orpin.

The C30 11 seemed to over rev at normal road speeds around 35 mph and this was cured by fitting 15cwt diffs. On the other hand the C30 13 LAA does not seem to have the same problem, it may well have been fitted with higher ratio diffs some time in it's past.

I'll come clean my interest has been brought on by acquiring a C30 12 cab LAA from Steve recently. It's in need of full restoration and currently has gone to the back of the barn while other projects are completed.

Calling David Hayward,

David do you have any info on when the first Chev LAA's were produced?

Pete

[Pete Ashby]

David

anything to add to this thread?

Pete

[David_Hayward (RIP)]

H 4999629 to 4999724 SM 2573 TRACTOR 4 X 4 LT. AA ARTICIZED. Known C.30- 444-M LAAT 2 Serial # 2844122313 Built 20/8/42

E.G. H 4999629 IWM PHOTO KID 1416

On checking my 1942 DND War Contracts file I see that 48 trucks were delivered by October 1942 to S/M 2573. So, these were built summer '42 onwards.

Then we have another batch:

H 5582513 to 5582612 SM 6065 TRACTOR 4 X 4 LIGHT AA
POSSIBLY IWM PHOTO KID 2923 Erroneously captioned 'S/M 6106' which was an articized Tipping C60S.

On F30 chassis we have an earlier contract:
H 5589105 to 5589404 SM 2487 Tractor 4x4 Light AA e.g. IWM PHOTO KID 1968 then

H 6100201 to 6100448 & H 6243634 to 6244553 SM 6111 Tractor 4x4 Light AA e.g. H6100380 assembled by Pearson’s, Liverpool
1944: photo Diamond T book P.27 ..I believe[d] that this was a F60S chassis
and also

H 6100505 to 6101404 SM 6143 Tractor 4x4 Light AA



E.g. FORD F 60-LAAT-1 CHASSIS F 60 CAF/3
CHASSIS SERIAL 197541 ENGINE SERIAL 4G-47804
SM6143 BUILT JULY 27 -44 [F60S Model C29QF]

So it would appear on the face of it that the switch from 30-cwt to 3-ton swb was using Ford chassis, whereas they stuck with the C30S. Interesting!

[David_Hayward (RIP)]

Yet another query! I am working on some photos of mysterious 2-wheel trailers, one of which is X 5819132. These were used with the F60B Bofors CMPs, and were apparently built by Clarke & Co. I cannot find any Census Number listing for these trailers, and neither can I find a listing in the book either! Anyone help please?

I noticed that the F60B CMPs had 'H' prefixes initially as they were 'tractors' but by late '44 they had 'S' prefixes for 'self propelled mountings'.

[Richard Farrant]

Originally posted by David_Hayward
Yet another query! I am working on some photos of mysterious 2-wheel trailers, one of which is X 5819132. These were used with the F60B Bofors CMPs, and were apparently built by Clarke & Co. I cannot find any Census Number listing for these trailers, and neither can I find a listing in the book either!

David,
According to the Chilwell Census list that number falls in a contract of 1 ton 2 wheel GS trailers by Willys, no's X5819091 to X5819290, Contract no. SM6288.

Richard

[David_Hayward (RIP)]

..Richard. Shows you need the Chilwell list in full!

I wonder if a Mack NM 6 x 6 G/S is listed..L 5559024to S/M 6242? It's not in my list.

Originally posted by Pete Ashby
I find the reason stated for up rating the wheel size interesting.

I would have thought that pulling a Bofors gun would have favoured lower ratios i.e. 30/60cwt diffs and smaller wheels. Improved road speed with lower transmission/engine stress would not I would have thought been an issue here, can anyone shed some more light on this?

As you know I am no expert on CMPs, but there are 240 needles in a FV 623 hub reduction planet gear assembly. . . . . . . . . . .

Thinking from just an engineering/application standpoint, it seems sensible, given the tyre load ratings of the day and to afford better off-road mobility when towing even a relatively light Bofors gun, to use a much larger tyre/wheel combination which affords enhanced load capacity and a better footprint grip with increased rolling radius.

Personally, if I were designing the vehicle with what they had then, this would be the choice together with an increased diff ratio to regain the original speed capability or even lower it further to account for the trailed load.

In the case of artillery or LAA tractors wouldn't the application be largely static? Even such pieces as a Bofors gun would likely be set up for days in one location before moving forwards a few miles now and again. Even in one day, ± brew-up stops, you could do a fair distance at 10mph. Of course perhaps we should see the vehicle-mounted Bofors guns as a "rapid-reaction" arrangement.

It seems to me that 20mph was largely adequate for all WWII applications and convoy speeds were probably much less than this, perhaps even half. I don't think today's army would convoy much faster even now, and for convoy I don't mean just a couple of MKs, a DAF and one Landy going down the motorway.

We hear little of the Italian WWII MVs, these are often epitomised by smallish vehicles with grossly "oversized" wheels/tyres, they look awkward but may well have excellent mobility.

We don't know what typical previous civvy applications may have done with mix 'n match parts encouraged by the very availability of compatible spares like diffs. I know Brian K has towed his Bofors hundreds of miles behind his LAA CMP and reports the going very slow relative to modern traffic but generally 20mph is quite possible if you give the old flathead V8 some stick - wouldn't do for Ballard however. . . . . . . . . .

The Ford diesel conversion was little better except for reduced gear changing but brought a crippling penalty in noise; as you know it now has a French "big-bore" V8 which is a noticeable improvement but all largely superseded now with a suitable artic carrying rig. He could likely tell you more and the exact diff that is currently fitted.

I note from Ballard's B&W tape of the British haulage industry of the 50s and 60s that the vehicles even then were rigidly classified as 20 and 30 mph trucks; the 30mph types being used for local distribution/collection and the larger 20mph types for movement between national depots. Crikey, even as a kid I can remember larger trucks all having 20mph rear plates.

Interesting stuff indeed.

R.

[Richard Farrant]

Originally posted by David_Hayward
..Richard. Shows you need the Chilwell list in full!

I wonder if a Mack NM 6 x 6 G/S is listed..L 5559024to S/M 6242? It's not in my list.

David,
This is weird.....that number falls in the group 5558376 to 5559875 and is shown as Willys and Ford car 5cwt 4x4, the prefix being H. This prefix may be a mistake on Rob's part (Groucho Publishing) as the previous group was H, being a jeep it would be M.

Where did you come up with the Mack number? There are no Macks listed anywhere near this jeep entry.

Richard

[Richard Farrant]

Originally posted by David_Hayward
..Richard. Shows you need the Chilwell list in full!

I wonder if a Mack NM 6 x 6 G/S is listed..L 5559024to S/M 6242? It's not in my list.

David,

Cancel last message !!!!!!!!!!

The Mack number should be H5589024 to S/M 6242 Cat Ref 2, from the group H5589005 to H5589104 for Tractor 6x6 (Super) Heavy.

Richard

[David_Hayward (RIP)]

Richard, you are of course right about the number fitting into the Willys batch. However the photo before me has 'L' [we think..could be 'H' ..5559024...that '9' is clear. The photo is captioned '7 1/2 ton Mack S/M 6242'. A crate that one of these NMs came in states that it is a '6 ton Prime Mover'. These were ex-USA of course. I query whether someone has mispainted the '5' as a '9'?

[Richard Farrant]

Originally posted by David_Hayward
I query whether someone has mispainted the '8' as a '9'?

David,

Should that not be mispainted an 8 as a 5 ?

Richard

Originally posted by Pete Ashby
David

anything to add to this thread?

Pete

Spring washers, as well you know. . . . . . . . . . . .

R.

[Pete Ashby]

Richard

Cryptic in the extreme dear boy explain yourself Sir!!,

Me thinks you may have been talking to that dastardly man Ward?
Or are you referring to the wing support of my beloved C15A

Pete :

Originally posted by Pete Ashby
Richard, Me thinks you may have been talking to that dastardly man Ward?

Quite so, quite so.

Did you not think my connection of the spring washers to your "thread" was quite exquisite perhaps?



R.

[Pete Ashby]

Calling Glow worm

Your eloquent subtlety did not elude my perception dear boy

The context was most fitting

Pete (part time toff)

[Hanno Spoelstra]

Originally posted by FV623
It seems to me that 20mph was largely adequate for all WWII applications and convoy speeds were probably much less than this, perhaps even half.

Seems you are right - as always - as far as the speed indication on this Chevrolet Gun Tractor's windshield is authentic....

H.

http://tanxheaven.com/fedcol/museo_italia/53.jpg
Source: http://tanxheaven.com/fedcol/museo_i...seo_italia.htm

[David_Hayward (RIP)]

It seems that I have uncovered another mystery! Pearsons of Liverpool assembled F60B Bofors trucks with the Willys-built G/S trailers in say 1943. However by early 1944 they had apparently 'rebuilt' or 'converted' at least some of these to self-propelled units. The trailers went, and the prefixes on the Cemsus Numbers were changed from 'H' as 'tractors' to 'S' for 'Self-propelled units'.

The IWM official Kidbrooke series photo I have seen has an 'H' prefixed truck, whereas the early 1944 shot clearly shows no trailers and 'S' prefixed numbers. The IWM has an official shot of the rebuilt C60L 6-pdr Portees..GM of Canada published shots of the original but the IWM has the only one I have seen so far of the rebuild to G/S trucks. Note the Number 43S and 43 cabs in both cases respectively. In both cases there seems to have been a short period between assembly in the UK and conversion.

Originally posted by Hanno Spoelstra
Seems you are right - as always - as far as the speed indication on this Chevrolet Gun Tractor's windshield is authentic....

Well, nothing very clever, I'm sure you can find a ton of WWII pictures with British trucks displaying a 20MPH plate on the back, and of course it spilled over into civvy life after that as I can personally recall.

R.