Chevrolet 1533X2 30-cwt trucks

[Grant Bowker]

This doesn't apply directly to the 1533x2:
When fitted to a Chevrolet CMP, the pump is driven by PTO attached to the left side of the transmission, engaged by twisting a rod with slot in the end using a screwdriver or similar tool through a hole in the floor. On CMP, the air output line ran to a fitting mounted on the frame rail adjacent to the pump. Based on the photos of the trucks, the frame rail isn't readily accessible so either an extension to the airline, relocation of the line or an access door would be needed. One of the photos in post #19 above shows a couple of projections on the filler panel between running board and cab (at the forward edge) that might be an air fitting. I hope someone with more knowledge can give you a better answer.

[Charlie Down]

Thanks for the reply Grant. Based on the information you gave I had a good look at my 200 odd LRDG truck photo's. I looked at the area below and around the door frame, as you suggested. The running board on most LRDG trucks was loaded with stowage, quite often running its length, with extra boxes, spare wheel on the Breda gun trucks and cans stowed in front of the standard rack containing 3 x 2 gallon POW cans. This means that if the airline came out in this area on a vertical surface the stowage would block access, which doesn't make sense. This left the horizontal steps, which don't show up well in photos, due to the canvas door at the front, stowage at the rear, troopers in the way etc. However I did find this intriguing photo of a 20mm Breda gun truck having a tyre change. A trooper seems to be lifting a flap on the step, which ties in with your comments, would give the crew access when the running board was heavily stowed, is central to the vehicle and explains why its not visible in the other photos. Would this be a possible solution to the question? Does it make sense considering standard fitting on other vehicles? Also would there be one on the other side too? Are there any photos of this arrangement on other MCP Chevrolets?
Annoyingly I've looked at this photo a hundred times and never noticed that detail!

[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.

[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.

[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.