CMP Roof Hatches

[chippyrail]

Hi,
Can anyone tell me what year were the hatches fitted to the cab 13 roof. I am making a model using the Italeri kit but most of my referance photo from the Western Desert c 1942 do not show a hatch of anykind.
Thank in advance,
regards Howard,

[cletrac (RIP)]

They started putting roof hatches in the 1941 Cab 12s. Most of the 1942 to 1944 cab 13s had roof hatches but some didn't. In late 1944 they started doing away with them.

[chippyrail]

Thanks David, I have built a couple of cab 13 kits upto now but have more conversions to make but all desert ones. thank again for the info,
Howard

[Phil Waterman]

Hi All

I'm not sure that clear starting date can be drawn, I suggest this because in reviewing the many original photos posted over the years on MLU you see large numbers of Pattern 12 cabs with the square hatch. I think that some of the lack of a definitive statement also comes from differences in introduction date between FORD and CHEVROLET then add in Canadian vs Australian production. Also there is the possibility that the early square hatches were retrofitted to earlier Pattern 12 and 13 trucks which had originally been manufactured without them but shipped as knocked units for assembly.

The HUP family of CMPs seem to have hatches from beginning to end.

Neither my `41 Pattern 12 C60L or `42 Pattern 13 C60S have hatches while my `45 HUP of course has the round hatch.

Ok, who has got the production notes/logs to sort this question out?

Now back to Howards question concerning North Africa and the introduction, of observer openings in the roofs of CMPs. I'd suggest doing a search on the http://www.awm.gov.au/ if you have not already done so. Lots of interesting photos. I do remember being told or reading that the origin of the observer opening was in response to the issue of not being able to hear aircraft approaching when ridding in a CMP. I have noted that in a lot of photos of CMPs on the move in the Desert there is somebody standing in the back of the truck behind the Cab who I suspect would indicate the approach of aircraft to the driver by pounding on the roof of the cab.

Cheers Phil

[cletrac (RIP)]

Phil, I looked through all my pictures and the pilot model of the Chev artillery tractor (Cab 11) had a roof hatch as did all the other FATs I have pics of. The only non FAT Cab 11 with a roof hatch is one with a canvas hatch in the western desert. Most of the Cab 12s have the regular square hatch but on the early ones quite a few don't have one. Most of the Cab 12s on the Factory Photos also have them. An August 1942 Cab 13 has the hatch.
My Cab 11s don't have hatches but all my Cab 13s except a 45 C60 have square hatches. My HUP has the square hatch too.

[David Dunlop]

Did Ford ever install the round roof hatch on their Cab 13 CMP's? In this part of Canada, I think I have only ever seen the round hatch installed on the Chev Cab 13's. Perhaps it is just a distribution of product thing.

David

[Grant Bowker]

I have understood that the rectangular hatch was early production, round came later and once they felt air superiority was achieved (or for domestic use where the wasn't much air threat) no hatch. Of course, no hatch had another benefit besides saving materials - no rain on the co-driver's head.

[Phil Waterman]

Hi David

You've asked an interesting question, which is as Grant suggest probably has a varied answer. Which will take some digging through period photos to find information.

To add to the question was Australian and Canadian hatch introduction and practice the same?

Cheers Phil

[Grant Bowker]

As follow-up to Phil's comment about Australian/Canadian differences, some of the parts books also make mention of differences for British army contracts as opposed to Canadian but I don't remember if this is Ford or Chevrolet (or what component it applied to).

[Ian McColl]

Hi David,

The answer to your question is yes. Ford CMPs did come equipped with round roof hatches like their Chevrolet counterparts. I have a late 1944 F60L with a round hatch and have seen many other late model Fords with them as well (both in person and in photos). Like the Chevrolet's they came into production in the 1944 time frame; however, which hatch (or lack therof) a truck was supplied with often depended on the specific contract. I have never personally seen a 1944 or newer truck with no hatch (round or square - aside from those removed once in civilian hands).

Ian

[Keith Webb]

I've only ever seen evidence of one round roof hatch on a Ford here; that was the first CMP owned by Tony Wheeler and it had been sheeted over.

Normal practice here was both Ford and GM-H fitted local design hatches. The GMH one being similar to the Canadian rectangular design but local Fords had a double skin hatch with radiused corners, very susceptible to rust due to condensation inside. I believe these were made by an outside supplier - smaller versions were also fitted to cab 12 Fords and Dodge T110s.

[Hanno Spoelstra]

Originally Posted by Ian McColl

The answer to your question is yes. Ford CMPs did come equipped with round roof hatches like their Chevrolet counterparts. I have a late 1944 F60L with a round hatch and have seen many other late model Fords with them as well (both in person and in photos). Like the Chevrolet's they came into production in the 1944 time frame; however, which hatch (or lack therof) a truck was supplied with often depended on the specific contract. I have never personally seen a 1944 or newer truck with no hatch (round or square - aside from those removed once in civilian hands).

Ian,

I concur with that. Canadian production configurations were indeed the same for Ford (see first pic) and Chevrolet. Actually, the square roof hatch was optional on all models, See second picture; but I recon in practice it was fitted to many if not most mid-war production CMPs, and it was superseded by the round one in 1944/1945 production. It was not so much of a hatch, more a round hole with canvas cover.

Keith is referring to the Australian assembled CMPs, which differ from the Canadian ones in this respect.

Hanno

[Alex van de Wetering]

I agree with Ian on the round roof hatches; I have seen several period liberation pictures of F60L GS trucks with round hatch....and also Ford 3 Ton LAAT.

Like Ian and Grant I believe square vs round hatch is an early vs late thing. I am not sure if it has anything to do with air superiority, though. I believe it was more an ease of production thing.....the round hatch is largely made from wood with a canvas cover....much simpler than the square steel hatch with hinges etc.

The roofs without hatch.....you see them a lot when you start checking pictures closely. First I thought the closed roofs might have been fitted to non frontline-vehicles, like the C60X Machinery trucks, Wireless vehicles and medical vehicles........but, they also appear on 3 Ton GS trucks in 1944/45 liberation pictures.....both on Chevs and Fords.
Ian could be right here.....contracts were leading (?)

Alex

Here is a picture taken in Utrecht 6 June 1945, memorial D-day parade. To the left a C60L without hatch....to the right a Ford F60L with round hatch. source: http://www.hetutrechtsarchief.nl

[Ian McColl]

Aside from timing, an example of differing hatch types (and Hanno is right in that the round version is not so much a hatch but rather a "hole" with a canvas cover) and particular contracts pertain to two 1944 Chevrolets of which I own examples of both. Trucks from contract PE-197-11 came supplied with square hatches while those from contract PE-197-12 came supplied with round hatches. Both contracts have been discussed on this forum before (PE-197-11 C60L's were supplied with winches and PE-197-12 C60L's were supplied with 16" wheels. Both contracts had "REL" (Research Enterprises Limited) tags on the rear inner of the cab roof.) As a result it would appear that trucks could be "ordered" with a limited number of "options" based on what was deemed necessary for that particular contract.

[David Dunlop]

Glad to learn both Chev and Ford both took part in the evolution of the CMP roof hatch.

Purely speculation on my part, but these hatches seem to be primarily a means of getting a better view of ones surroundings. In some theatres that was probably a useful feature. In others, perhaps not so much. Maybe that is why the presence of the hatch varies by Contract.

I just had a further thought. I wonder if these hatches are discussed/covered in the Design Branch books? Maybe they actually had a formal name there, as well as an explained purpose.

David

[Keith Webb]

Many Australian CMPs were fitted with a counterbalanced mount for a Bren gun for anti aircraft defence.

[David Dunlop]

OK, maybe it's late and my brain is getting a bit dotty, but it seems to be wanting to convince me that the early, square metal hatches had a small tubular rail, like a towel rack, mounted on the roof of the cab, at the front of the opening. Looking somewhat like a grab rail. Is this correct? Was it a grab rail, or was it rail to take a sliding gun mount of some sort? Or am I just experiencing another brain fart?

David

[rob love]

I had a look in the design branch records and it confirms Grant's synopsis. It refers to the rectangular as "old style" , and the round ones simply as "hip ring". There is one page of photos (volume V, page 27D)

The front handle was a grab bar as far as I know. The manual calls it a "grip handle - roof.

[Keith Webb]

Yes it is a rail which acts as a grab handle. The Australian Fords had two small grab handles rather than a rail.

Originally Posted by David Dunlop

OK, maybe it's late and my brain is getting a bit dotty, but it seems to be wanting to convince me that the early, square metal hatches had a small tubular rail, like a towel rack, mounted on the roof of the cab, at the front of the opening. Looking somewhat like a grab rail. Is this correct? Was it a grab rail, or was it rail to take a sliding gun mount of some sort? Or am I just experiencing another brain fart?

David

[Hanno Spoelstra]

Originally Posted by David Dunlop

OK, maybe it's late and my brain is getting a bit dotty, but it seems to be wanting to convince me that the early, square metal hatches had a small tubular rail, like a towel rack, mounted on the roof of the cab, at the front of the opening. Looking somewhat like a grab rail. Is this correct? Was it a grab rail, or was it rail to take a sliding gun mount of some sort? Or am I just experiencing another brain fart?

David, as you said: these roof hatches are primarily a means of getting a better view of ones surroundings. Often people speculate about gun mountings fitted on the hatch/roof, as if the sheet metal CMP roof could withstand the recoil of sustained MG fire recoil. Maybe it is just that some collectors or modelers want to pack their CMP with a some punch, akin to the poor overloaded LRDG / SAS jeeps.

Apart from the Australian efforts - see below - I have not seen any documented proof these hatches were to be used for anything else than observation.

Originally Posted by Keith Webb

Many Australian CMPs were fitted with a counterbalanced mount for a Bren gun for anti aircraft defence.

The photo below shows the gallows in the proximity to the cab roof hatch from where the gun would be fired suspended. My question is: how often was this used in practice?!?


Source

[Grant Bowker]

Without being told that the gallows were for a gun mount, I would wonder if they were intended to aid in hoisting spare wheel assemblies into the boxes behind the cab. Possibly making a 2 man job into something one man could hope to do.

[rob love]

On the milsurps forum, Peter Laidler talks about the lunacy of taking on an aircraft with it's 20 or 25mm guns, and you with a .303 having to run around a tripod mount. Trying to take one on from the large target of a truck cab is even crazier. From the vantage point the aircraft is using, the Bren would not even be in range to fight back.

[Hanno Spoelstra]

Some hatch pictures courtesy of Keith Webb:

Close up of a Canadian hatch on a Ford F15A:


Australian roof hatch as fitted to Ford cab 13 CMPs, although this double hatches next to each other was unique to the FGT No9:


For comparison here is the Australian Chevrolet hatch as made by Holden, similar to the Canadian one but again a bit different. It has a harder rubber surround which was formed in one piece. This one is on a Wireless Signals van:

[Mike Cecil]

The Aust Chev hatch was also only suitable for an Aust GMH Chev roof - there was a flat pressed into the roof to take the hatch, which was bolted in position.

The Cdn hatches had a curved wood filler piece between the hatch and the curved cab roof, with no pressed flat, and was the same for both Fd and Chev.

The Aust Ford hatch attached to a pressed metal coaming that was welded into the roof.

Mike

[Keith Webb]

The Australian Holden made hatch had a formed rubber seal which fitted over the roof opening, while the Australian Ford used four strips of slightly spongy rubber glued to the inside of the hatch.

[Mike Cecil]

Keith,

I've always found it interesting that the two companies achieved the same end (well, sort of!) using very different methods.

I suspect the GMH Chev seal was the more durable (just like their hatch design - as you pointed out before, the Ford hatch was prone to rusting out from the inside of the two-piece 'sandwich'.)

I also liked the Chev single-piece grab handle, rather than the Ford top-hat section fitted with two standard 'hardware' handles. In all, the Aust Chev hatch, hatch aperture and locking system seemed to be a much better design than the Aust Ford. What do you think?

Mike

[Keith Webb]

Originally Posted by Mike Cecil

I also liked the Chev single-piece grab handle, rather than the Ford top-hat section fitted with two standard 'hardware' handles. In all, the Aust Chev hatch, hatch aperture and locking system seemed to be a much better design than the Aust Ford. What do you think?

Mike

Couldn't agree more... the Holden design is superior in almost every respect - even the less fussy catch to stop them bouncing when open, to the proper door style lock rather than a flimsy spring loaded hardware store type catch on the Ford.
The GM-H hatch is also a simpler roof fitting compared with the Canadian type.
It's interesting the Kiwis decided to go a different way and designed a sliding hatch as can be seen in post #17 by Hanno in this thread.

[Hanno Spoelstra]

Recently someone was looking for an inside view of the late Cab 13 with round roof hatch:

[m606paz]

This is a pic to see how the spring work

[Hanno Spoelstra]

Originally Posted by m606paz

This is a pic to see how the spring work

Better