Chev HUW door switch question

[Bruce Parker (RIP)]

The Chev HUW wireless van has 'kill switches' on the rear body doors so that when open the interior lights switch off so the enemy won't see them.

I've been puzzling over how these work, but have enough evidence (pic 1) that they are similar to a closet switch available today (pic 2). These operate with a plunger (which would have to be altered as these switches turn the lights on when the door is open and I need them to turn off). But the real question I have is this: on the HUW these switches are located on the latch side of the door and not the hinge side meaning the back of the door would hit the side of the plunger instead of pushing it so it won't work.

But then I notice two small holes (pic 3) that take threaded screws and are dead centre for the switch plunger (so unlikely used for mounting the switch). The Petawawa HUW (pic 4) even shows a thin metal tab the screws hold in place. So what's going on? Could the tab be a flat spring that bends into the door jamb such the when the door closes the spring tab depresses the switch plunger? Seems strange and prone to breaking. Or am I completely off base and the switches are more like a spring loaded toggles instead of a plunger...but then what's the tab and two screws for? I'd really like to confirm the arrangement with someone who knows or has a photo of an open door with the switch in place.

[Jordan Baker]

Could that tab simply be a plate attached to cover the switch and keeping the lights on all the time? It makes the switch think the door is always closed.

Or the plate acts as a depressing cover so the door closing doesn’t hit the side of the plunger and break it off. Basically like a strike plate on a door.

[Bruce Parker (RIP)]

Originally Posted by Jordan Baker

Could that tab simply be a plate attached to cover the switch and keeping the lights on all the time? It makes the switch think the door is always closed.

Or the plate acts as a depressing cover so the door closing doesn’t hit the side of the plunger and break it off. Basically like a strike plate on a door.

Thanks Jordan. I'm tending towards your second option. If it was a method to keep the lights on all the time (and remove the plates to operate in blackout mode) why the trouble of two screws per door.

The plates are a feature and even appear in the wartime factory photo.

[David Dunlop]

A few questions, Bruce.

With the rear door closed, and properly aligned, how much free space (gap) do you have to work with between the edge of the door and the latch side frame?

With the door closed, does the large switch plunger hole disappear completely behind the edge of the door?

Do you know if the switch mounts directly against the inner face of the frame, or is the switch set back a bit from the frame by some form of spacer?

David

[Bruce Parker (RIP)]

Originally Posted by David Dunlop

A few questions, Bruce.

With the rear door closed, and properly aligned, how much free space (gap) do you have to work with between the edge of the door and the latch side frame?

With the door closed, does the large switch plunger hole disappear completely behind the edge of the door?

Do you know if the switch mounts directly against the inner face of the frame, or is the switch set back a bit from the frame by some form of spacer?

David

The gap between the body frame (with the switch) and the side of the door is about 1/2". The plunger hole (the big one) meets the middle of the vertical side of the door. The square flange of the switch mounts behind the door frame with only the plunger and two mounting screws projecting on the door opening side. I see no evidence of a spacer.

[David Dunlop]

Hi Bruce.

Sorry for the lack of colour in this quick sketch. the scanner is sulking tonight for some reason.

Back in the 1950's in these parts of the country, a very popular weather seal for exterior door was a slightly corrugated strip of spring brass, fitted to the door frame with brass nails. a quarter inch flat strip of the brass went at the outer edge of the frame and the brass strip angled in towards the door.

I think a similar concept in spring steel might have been used on the HUW to activate the door blackout switch. Very rough drawing attached.

A spring steel strip of the required width would mount to the two exterior holes close to the door frame. the strip would wrap around the door frame at 90 degrees and fit flush to the inner frame surface maybe one quarter to three eighths of an inch. This would prevent the door from binding against the metal strip. as the door moves further inward, it starts to flatten the spring steel against the door frame. at the open end of the strip, a small metal cup is rivited. this cup fits over the switch plunger and inside the plunger hole in the frame. The cup would need to be long enough to stay inside the door frame with the door open to avoid snagging on the frame.

I think the travel distance of the plunger will be critical for the right switch, and also as you mentioned, you need to find a spring loaded safety switch that shuts off when released, not turns on.

In the photo you posted of the two original switches, the one on the left looks like it has a circular collar fitted part way down the plunger. That might be a means for the cup on the spring metal strip to better engage with the plunger. Or I am dreaming again.

Hope this helps and doesn't muddy the waters too much.

David

[maple_leaf_eh]

I recall the door seals on the modern MLVW SEV boxes was a series of little fingers that were not unlike the conversation about, except not a continuous strip but 1/4" fingers perpendicular to the motion of the door. Same thing only different.

Likewise, the red light on/off switch was high up on the box like you've illustrated. The switch was different, just a spring finger that was closed when a door latch (a big interconnected set of latches actually) pushed it closed. Turn the door latch without thinking about the light colour, and there was enough of a closure seal to get the lights switched over before the door swung open.

But .... getting back to the repurposing suggestion, why not? The idea of wartime production was to use available commercial or industrial products that were suited. So a plunger light switch mounted in the door frame isn't far off.

[David Dunlop]

One more crazy thought before I call it a night, Bruce.

Following on what Terry just said. The wheel was very likely not reinvented when the CMP’s were designed and built. Commercially available items would have been used wherever possible to save time and money.

The blackout switches used on the 15-cwt Wireless 5 2K1 and 2K2 Bodies were a thicker style than those on your HUW. The plungers on them also functioned directly against the inside face of the rear entry door and Generator Compartment door, so much simpler operating action.

I wonder, however, if the same company perhaps made both switches commercially pre-war? If Gord Falk, or any other WIRE 5 owner with original blackout switches still available could check them for maker stamps, it might help trace the switches you need. Could be LEVITON, or any other prewar electrical supplier.

Also just a thought. If your generator is running, the exterior hatch would be open. Was there a blackout switch on the inner compartment door somewhere as well?

David

[Bruce Parker (RIP)]

Thanks for your comments Jordan, Terry and Dave. I'm now almost certain the two screws and plates are spring tabs that the door 'ramps' on when closing to depress the switch plunger (as in Dave's sketch).

As to the remaining blackout provisions, each door window, the upper right side window above the spare tire and on the sliding windows that separate the body from the cab each have a rolled up vinyl cover and dome fasteners to keep them in place when down. The generator cabinet doesn't have a blackout switch. It has that sliding, insulated steel panel that would keep the light inside when the outer doors are open...providing the crew remembers to close it before opening the outers.

[David Dunlop]

Bruce, it might be worth sending that photo of the current LEVITON switch to them and asking if they have the same style available but with the switch ‘ON’ when the plunger is fully depressed. They probably do. The plunger assembly in the photo is threaded and a locking ring is holding it in place. Chances are the plunger itself is repairable/replaceable and the right version easily inserted.

You could make an adapter plate to mount that switch to with countersunk screws and then drill the adapter with two new holes to match the original pattern in the door frame where the plunger is centred between the two mounting holes. Assuming you have the wiggle room behind the frame to work with.

David

[Paul Singleton]

Honeywell makes a micro switch that you could probably make work. Here is an Amazon ad, but you could probably shop around and find one locally and maybe a better price.

https://www.amazon.ca/Honeywell-Over.../dp/B0839NYHFR

[Bruce Parker (RIP)]

I think that settles it for me. I dug out a file with photocopies I made many years ago at the old Kingston Signals Museum. Here is an interior shot taken from the inside looking rear towards the back door and left door frame. The left side of the photo is the folding map table attached to the rear door, above it the sliding glass window and padlock, and to the top right the open generator cabinet. It is basically the inside of the pic I included before, the green arrow showing direction. The closeup shows the door frame with the two switch mounting holes (oddly the switch isn't all that visible), wires, and it clearly shows a metal tab...I bet spring steel...that wraps around the door frame, covering the switch plunger which it would depress when the door is closed. All held in place by those two screws on the outside. It also explains the mystery bump that shows up in the last pic.

As a side benefit the old photocopy also tells me where the exterior brown stops and the interior white begins...

[David Dunlop]

Great find with the old photos, Bruce.

I had not considered extending the length of the spring steel strip to curve around the inside edge of the door frame like that.

That would greatly reduce the chance of the open end of the strip snagging on clothing and getting bend or broken. Especially when the door was open and the strip relaxed.

David

[Bruce Parker (RIP)]

Originally Posted by David Dunlop

Great find with the old photos, Bruce.

I had not considered extending the length of the spring steel strip to curve around the inside edge of the door frame like that.

That would greatly reduce the chance of the open end of the strip snagging on clothing and getting bend or broken. Especially when the door was open and the strip relaxed.

David

I was also wondering why they placed the switch on the latch side of the door where the plunger would be at right angles to the movement of the door. In domestic house uses the switch is on the hinge side so the closing door pushes the plunger in the direction it wants to go. But then I figured the amount of movement at the hinge side is very little compared to the latch side resulting in more door travel before the switch is actuated (leaving the lights on longer to be seen). By putting the switch at the latch side very little door movement is required before the the switch breaks the circuit reducing the opportunity for stray light. They were some clever back then!!

Of note too the side door has the switch and spring tab at the very top out of the way. The back door switch is just below the generator cabinet half way down the door opening which was required because there is no access to the upper part of the door frame...because of the cabinet.

[Bob Carriere]

.... but in your own back yard Smith & Stone made a lot of switches during the war and well after ....even 303 brass casings...... they were on a par with LEVITON.......

[Rob Fast]

Amalgamated. That is my photo in an early MLU HUW posting. Pics came from Southampton UK from a HUW there years ago. Cheers

[Bruce Parker (RIP)]

Originally Posted by Rob Fast

Amalgamated. That is my photo in an early MLU HUW posting. Pics came from Southampton UK from a HUW there years ago. Cheers

Yes Rob, you sent me that pic years ago and I've kept it as my best evidence of what I was looking for. On the metal tab depressing the switch post, am I close to what you think is correct?

[David Dunlop]

Amalgamated Electric Corporation Limited

160 Bullock Drive
Markham, Ontario

Headquartered in Montreal, Quebec

Established in 1929 and purchased by Federal Pioneer Limited in December, 1982. Their 1946 Annual Report lists, SWITCHES, Door; and SWITCHES, Safety; among their specialties.

David