Chevrolet 1533X2 30-cwt trucks

[Charlie Down]

You mean this one Hanno? And thank you Hanno for your help and advice.

Here's what could be the only photo of the PTO air compressor being used on a LRDG truck. Unfortunately you can't see where the airline goes, but it could be under the truck to the connector on the LHS of the cab. I like to think so....

Does anyone have photo's of the relevant area LHS lower door frame and running board ) to show confirmation and details of the flap covering the airline connector. Could finally solve 78 year old mystery!

[Charlie Down]

As an after thought. If there was a flap below the LHS door in the bodywork, was it a standard fitting and therefore wouldn't there be a replacement piece of bodywork with a flap in it to fit the compressor kit? If so, it would be in a catalogue, vehicle manual, or something similar. Does anyone have that information, and could you post the picture or details to finally put this to bed please. TIA

[Charlie Down]

In this photo there seems to be an outline of a flap, maybe a knockout plate on a MCP Chevrolet Truck. Its quite faint. I hope that the PTO compressor kit came with a modified panel as shown to allow a flap to be fitted discreetly to a truck.

[Keith Webb]

Here's a factory photo of the tyre pump on a 1533X2 Chevrolet. It's the same as used on the CMPs.

[Charlie Down]

Hi Keith,
Nice quality photo, however the controls for the pump on the 1533X2 were different. The 1533X2 controls came out the side of the cab on the passenger side door sill next to the airline connector, as opposed to the screw driver being used through a hole in the cab floor. See photo on reply no 209, page 7 of this post.

Do you have any other factory photos you can share?
We have nearly covered every detail of the 1533X2 on this post and always looking for more information/photos to complete the picture or confirm theories.

[Keith Webb]

I realised when I checked it was the GMEXL7, not sure which of the MCP configurations that was.
These are the other photos I have, they have been enlarged by a factor of 4X from quite small images.

Originally Posted by Charlie Down

Hi Keith,
Nice quality photo, however the controls for the pump on the 1533X2 were different. The 1533X2 controls came out the side of the cab on the passenger side door sill next to the airline connector, as opposed to the screw driver being used through a hole in the cab floor. See photo on reply no 209, page 7 of this post.

Do you have any other factory photos you can share?
We have nearly covered every detail of the 1533X2 on this post and always looking for more information/photos to complete the picture or confirm theories.

[Charlie Down]

I've been looking at tracking down details of the charging panel on the Wireless trucks, and found some photos of Chevrolet WAs with a panel on the outside of the rear body. On the basis that the LRDG re-used items throughout their Desert campaign on different trucks, Aero screens and Wireless set ups for example, then the charging switch panel would most likely be re-used too. I was sent some documents by Bob Amos-Jones that were very useful too.
To summarise what I found out I'll cover the whole wireless setup. The LRDG used a WS11 High Power unit with Windom centre feed or sometimes end feed aerials on 16' duraluminium poles stowed on the trucks, and the 4' rod aerials for local (100 mile range) communication between Patrols. The power supply was fed through a 'Special' series/parallel switch for trickle charging/wireless use, from 2 standard 6 Volt batteries, one the truck battery, the other a 'booster' battery to provide the necessary 12 volts with the truck battery for the wireless. The 'booster' was mounted on the side step in front of the driver. During long periods of stationary Patrol, Road Watch, the Patrol would either take a chore horse to recharge the batteries or swap batteries with the other trucks in the Patrol. Very high levels of training were given to the signallers, this being the primary reason for the successful long range communication, not the limitations of the wireless. Very high levels of maintenance were given to the wireless and accessories throughout the Patrol too. No information is given on what periods of the campaign chore horses are used, but it seems they were more common later on. I suspect that all the Chevrolet 1533X2 trucks, and most likely the CMP Ford F30s were fitted with wireless suppression fittings as standard, but on the WA's not so sure. Most likely the ones from the Egyptian Army would be suppressed, which would therefore be primary choice for wireless trucks, but not the ones sourced from the civilian dealership in Alexandria.

I've put a drawing together of the series/parallel switch based on the photos attached (not dimensionally accurate and most likely wrong with some details, but its something to work on!), and on the assumption its the same switch, but on the Chevrolet WA's it had a protective edge due to its external mounting on the outside of the rear body, but on the Chevrolet 1533X2 no protection was needed because it was mounted in the cab behind the Drivers seat. No photos found yet of its location on the Ford F30's, but its not externally mounted on the rear body, or in the cab, based on the limited number of photos showing those area of wireless trucks. It may be mounted in the plywood wireless compartment, or possibly in one of the tool boxes below the wireless compartment. Hopefully something will turn up.

[Andrew H.]

Originally Posted by Charlie Down

You mean this one Hanno? And thank you Hanno for your help and advice.

Here's what could be the only photo of the PTO air compressor being used on a LRDG truck. Unfortunately you can't see where the airline goes, but it could be under the truck to the connector on the LHS of the cab. I like to think so....

Does anyone have photo's of the relevant area LHS lower door frame and running board ) to show confirmation and details of the flap covering the airline connector. Could finally solve 78 year old mystery!

Am I imagining things, or is that an air-line going up the front of the seat riser? Looks like it might fit down into the space below the seat (I am referring to the photo in post #114 above).

[Grant Bowker]

Based on my belief that only one air outlet was provided on Chevrolet CMPs equipped with the air pump, it would surprise me if there were more than one provided on a MCP. Not saying it is impossible, just seems unlikely. I would have expected them to run the hose around the truck, under the truck, or through the cab - whichever seemed easiest to the crew at the time.

[Tony Smith]

On CMP's, the the installation of the the PTO pump involved nothing more than drilling a hole in the floor to insert a screwdriver to engage the pump, and fitting the pump to the transmission. A copper pipe ran from the pump to the air fitting, which was screwed through an existing hole in the frame. An experienced Driver/Mechanic could probably fit it in 15 minutes.

On the MCP, I can't believe there was anything as fancy or elaborate as modified body panels, knockouts or flaps. Too much work. The simplicity of Canadian vehicles was their forte.

I think we've been staring at the fitting all along and not wanted to see it, expecting something sexier than just an exposed fitting, but there it is.

[Hanno Spoelstra]

Originally Posted by Tony Smith

On CMP's, the the installation of the the PTO pump involved nothing more than drilling a hole in the floor to insert a screwdriver to engage the pump, and fitting the pump to the transmission. A copper pipe ran from the pump to the air fitting, which was screwed through an existing hole in the frame. An experienced Driver/Mechanic could probably fit it in 15 minutes.

On the MCP, I can't believe there was anything as fancy or elaborate as modified body panels, knockouts or flaps. Too much work. The simplicity of Canadian vehicles was their forte.

I think we've been staring at the fitting all along and not wanted to see it, expecting something sexier than just an exposed fitting, but there it is.

Tony, you're the man! Once one knows where to look, it becomes obvious.

[Charlie Down]

Hi Tony, your are correct about the connector not being obstructed on the trucks early in their use, spring /summer 1942, but by September, as the crews became more familiar with the trucks and they modified and adapted stowage arrangements, the connector was obstructed. The attached pictures are all dated September 1942 or later from S,T and Y patrol vehicles, and all have boxes/stowage blocking connector.
Its interesting that the trucks that retained the POW can racks all had similar boxes, and those that had the larger Vickers K drum chests mounted the rack on the drivers side in front of the other rack.

[Charlie Down]

Hi Andrew and Grant,
That could be an airline on Post 114, but a bit vague to be confirmed. Adds to the mystery. Attached photo shows what could be an airline behind the driver's seat near the rifle mount, not sure if that helps or not, although it focuses the area of the cab for its location. 6" of pipe not much to work on though.
The parts sheet only shows one airline connector from the pump, so only one connector makes sense.
Looking at the problem from another angle. If it was my truck, where would I want the connector located for easy access and connection, centrally on the truck? In the cab, obviously, not on the floor where it could be stepped on and kicked/pick up dirt and be a trip hazard. Not under a flap that could be damaged, knocked off or jammed. Not too low down so that I have to move stowage to get to it. Most likely I would mount it on the inside of the side panel of the cab on the LHS. I most likely wouldn't mount it under a flap on the side of the cab below the door.
MCP and CMP trucks were simple practical designs. the flap is out of character. It was a standard kit to fit MCP trucks, most of which had doors fitted, so access would require the door open and you would need to hold the door open to stop it slamming onto the hose and connector and damaging them.
But in that case what was the flap for? Have I mis-interpreted the original photo of the flap? Are there photos of CMP airline connectors fitted to trucks?
Are there specific panels to fit under the door with a flap on them? Sounds a complicated way to fit the kit if you have to remove a panel and weld/bolt a new one in to fit the connector.
More questions than answers! If pushed I would go for the flap arrangement purely because there is evidence for it, but I'm not convinced yet.

[Tony Smith]

Originally Posted by Charlie Down

MCP and CMP trucks were simple practical designs. the flap is out of character.

But in that case what was the flap for? Have I mis-interpreted the original photo of the flap?

Are there photos of CMP airline connectors fitted to trucks?
Are there specific panels to fit under the door with a flap on them? Sounds a complicated way to fit the kit if you have to remove a panel and weld/bolt a new one in to fit the connector.

More questions than answers! If pushed I would go for the flap arrangement purely because there is evidence for it, but I'm not convinced yet.

There is no evidence for any flap, either in a manual or a photo.

The airline fitting on CMP trucks just bolts through the chassis rail with no additional panels or fixtures. The MCP just passes through a hole drilled in the running board.

[Tony Smith]

Originally Posted by Charlie Down

Are there photos of CMP airline connectors fitted to trucks?

This is the Left side chassis rail of a 12 Cab Chev.

You can see the PTO port on the side of the transmission (Dark grey, no pump fitted), and the pre-drilled holes in the frame. A short copper pipe runs from the pump to the inside of the frame rail. The airline fitting bolts through the lowest of the 3 holes, connecting directly to the copper pipe.

[Tony Smith]

Originally Posted by Charlie Down

Are there photos of CMP airline connectors fitted to trucks?

Originally Posted by Tony Smith

This is the Left side chassis rail of a 12 Cab Chev.

You can see the PTO port on the side of the transmission (Dark grey, no pump fitted), and the pre-drilled holes in the frame.

Jaap De Wit has posted some good pics of his 12 Cab Chev which clearly illustrates the relationship between the position of the Transmission gear lever, the Air Compressor engagement shaft, and the Air Fitting hole on the Chassis in THIS THREAD

[Hanno Spoelstra]

Next topic on Chevrolet 1533X2 configuration: the rear axle. The requirements document of the LRDG posted by John J. Valenti specfies a 6.17:1 differential ratio.

From the “Desert Chevrolets” article in Wheels & Tracks magazine no.8 I copied the technical details of the 1940 Chevrolet WA. This had a differential ratio of 5.43:1, or 6.17:1 as an option.

I’ve read the 1533X2 was fitted with a 2-speed Eaton axle. Can anyone show the technical documentation to underpin this?

2B188792-D663-4F75-A854-7F96B31ADE73.jpeg

[Charlie Down]

Hi Tony,
I was wondering about that piece. It wasn't painted, meaning it was fitted after the paint job or it was masked to stop paint clogging up machining on the fitting. It makes sense. Simple, effective and quick to mount/repair/use. Very MCP/CMP in character.
However, initially I looked at period photo's of the trucks, and later stowage setups which often involve large wooden or metal ammo chests bolted to the step. It didn't make sense that they would have to unbolt these boxes to get to the airline, then remount the boxes when they were finished.
I then put myself in their position and thought about the problem. What if they drilled a hole in the stowage/ammo box, fed the airline through the hole and attached to the connector and then bolted the box in place. They would then only have to open the box, take the airline out and engage the PTO to use it. It would be quicker and simpler, they would have the airline stowed where they need it (freeing up space else where), the airline would only take up a small area of the box allowing it to be filled with ammunition or other stowage.
The first photo show S1 Patrol in September 1942 ready to go. They all have a chest for 10 x 100round Vickers K gun drum magazines fitted on the step. So a fairly standard fit for this Patrol. If you did the above, drilled and fitted the airline in the box you would still have plenty of room for 9 drums of ammunition.
I really like that idea and have absolutely no evidence for it, apart from that it's easy to do and makes sense! Its exactly what I would do.
The other photo's show (when magnified) the fitting on trucks in the field and at the factory. The rhs is shown to show it wasn't fitted on both sides.

So I have a new theory/idea.

And what the hell is that flap all about!

[Tony Smith]

None of the stowage pics show the airline fitting blocked or covered, the boxes are at the rear of the step, the airline is at the front of the left side step.

You are in a flap about this so-called flap! What on earth are you talking about, what flap?

[Charlie Down]

This photo shows what looks like a flap, which is what I'm trying to sort out. It has generated lots of conversations on here and the LRDG preservation society facebook page. Initially I thought it was the airline connection and started looking for evidence to prove this, which has by a convoluted path led me here where I am sure its not, but don't know what its is. So yes I'm 'flapping' about a flap, but what I really want to work out is how the airline was set up from the pump because it's never really been discussed in LRDG circles, but apparently MCP/CMP forums are much better informed!

[Hanno Spoelstra]

Some original documents referring to the Chevrolet 133" wheelbase trucks. The "W.B." in these documents caused some confusion, but these are in fact Chevrolet WA trucks.

132748462_1920195304795016_3756009213865161287_n.jpg 132188790_10157782435993148_5042062919135481054_o.jpg
(via Brendan O'Carroll and John Valenti)


From the “Desert Chevrolets” article in Wheels & Tracks magazine no.8 I copied the technical details of the 1940 Chevrolet WA.
117798106_1207321656271707_7590470014854090807_o.jpg


Edited to add: the above information refers to the Chevrolet WA 30-cwt truck used by the LRDG before the 1533X2 was taken into service

88EF1CF5-79B2-4F11-B833-2C37E3F02D96.jpeg

[Bob Carriere]

Hi Hanno

The "W.B." refers to wheelbase and not to "series WB.....by coincidence the 1940 WA series is the 133 inches and the WB series the 158 1/2 inches wheel base.....

On the first memo they refer to 113 wheelbase which applies to cars or at 113 1/2 for the 1/2 ton trucks.

Precious documents ........ and the magazine documents makes mention of either 900x13 ot 10.50x16 .........

Any idea which Heavy duty front axle they were requesting from General Motors....? GM did list a std front axle for the 3/4 ton Commercial KD with 11 inch brakes and the Heavy duty axle for the 3/4 ton Commercial KE with 14 inch brakes .......BUT with 123 3/4 wheel base........

Frame wise all 113 and 1/2 ton trucks had a curved frame above the rear axle......
.....all larger trucks 123 and larger the rear frame was flat from the rear of the cab to the end of the frame.

.....and GM also had the HD Maple Leaf front axle same as the HD Cab Over Front axle.

TONY........ I have a 1543X2 parts list, issued November 1940 ( no 167) and it does list the Eaton 2 speed axle....... but blank luck on the 1533!!!!!!

Two front axles are listed for the 1941 model....... one with ball bearings and one with cones and bearings for the "X" HD front axle using 10.50x16 tires. To me cone race /bearings denotes a model similar to the Maple Leaf HD or the COE......... The front wheel hub on HD is unique in having a small domed bolted cover instead of the recessed screw on cap ......

So much to learn........ so little time.

Cheers

[Hanno Spoelstra]

From Clive Law’s “Drive to Victory”:

56CCFF60-D1A7-49A6-95A6-2FACB1BD6067.jpeg

[Charlie Down]

Hi Bob,
I'm trying to get details of the bumper brackets. It looks like the 1533 and 1543 had solid brackets that raised the bumper to allow the starting handle to pass through the bumper, not the lower spring style civilian brackets. Is there any information in your 1543 parts list about these brackets or is the 1940 edition too early for this detail.
It also appears that there were supporting bumper rods outboard of the brackets that attached to the bracket on the chassis end and went through separate holes in the panel below the grill, before attaching to the bumper.
Trying to clear up this detail.

Many thanks

[Tony Smith]

Originally Posted by Bob Carriere

TONY........ I have a 1543X2 parts list, issued November 1940 ( no 167) and it does list the Eaton 2 speed axle....... but blank luck on the 1533!!!!!!

Cheers

The Major Assemblies manual shows that it it the same rear axle assembly (and subsequent superceding numbers) used on both trucks. Very heavy duty for the 1533! This might help someone seeking to scrounge parts from a donor truck to make a 1533 replica.

I see that the model code for both 1533 and 1543 are the only trucks with the two speed specified. I wonder if the xxx3 indicates "two speed" axle?