Chevrolet 1533X2 30-cwt trucks

[Hanno Spoelstra]

I think you have cracked the nut, Charlie!

Please post that other photo of the tyre inflation too.

[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.

[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

[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?

[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