Rob. Chorehorses are a bit like CMPs. At first glance at a distance they all look the same. Then on closer inspection, you start to notice subtle differences that identify some were Fords, some were Chevrolet, a few were GMC and a whole bunch more were even built at Holden in Australian...and then you develop an overwhelming urge to try and own one example of every type ever made and wonder why your neighbours start moving away...
The actual construction differences between manufacturers of the chorehorse were quite subtle since they all had to comply with the same set of military design specifications. If the data plate is missing from the set, you are pretty much guessing who built it, as the differences would be at the level of nuts and bolts, or the look of the meter. The guard frame was basically an option item and cannot really be considered definitive for identifying a 'military' or 'civilian' chorehorse. I have copies of both the military and civilian publications and the photos would be freely interchangeable between the two publications.
In military use, the chorehorse served two basic functions: it could be a field portable set, or a hard mounted set in a vehicle. Hard mounted in a vehicle, it would likely be installed and operated within some form of generator compartment, safely separated from the operators, or any careless Sargents wandering around, so the guard would not be installed. If the set was to be field portable, the guard would have been supplied as it served several purposes. It made the generator easy to carry, it provided some protection from dry vegetation coming up against it and starting a brush fire, and it helped prevent the operators from getting a nasty shock, burn or mangled fingers from spinning parts.
As with anything in the military, in spite of these two clearly distinct functions, the laws of supply and demand take over sooner or later and one would end up using whatever units were available.
About 40 years back, there was a very large surplus company here in town that had several dozen Chev 15-cwt Wireless Trucks in their yard. The Wireless Boxes were all built by Wilson Truck Body and they all came equipped with a standard wiring layout that would allow for two distinct generator installations in the Generator Compartment. The compartment held two generators, A lower one was hard mounted to the floor of the compartment and would not have a guard. It would either be a DC Chorehorse or a much larger Onan AC/DC generator (the actual model number escapes me at the moment, but it's output was 12 V DC and 110V AC). There was a large, round single AC receptacle mounted on the front wall of the Wireless Box, just to the right of the radio operator's table.
On the floor of the Generator Compartment to the left of the lower generator, there was a section of galvanized plumbing pipe sticking up with a Y-adaptor on top. Underneath the box, the pipe had a 90 degree elbow on it leading into a muffler that pointed to the right side of the vehicle. The Y-adaptor of the top of the pipe was asymmetrical in that the two parts of the 'Y' were different diameters and had a square head plug fitting screwed into it.
If the lower generator was a chorehorse, it's exhaust pipe was connected to the smaller part of the 'Y' and the larger pipe remained capped. If the lower generator was the Onan unit, it was connected to the larger part of the 'Y' and the smaller pipe remained capped.
About halfway up the Generator Compartment, there was a set of side rails that an angle iron frame could slide in and out on, rather like an oven rack. It was held in place on the left side by a large cotter pin on a brass chain attached to the side rail. The pin could be passed though a hole in the side rail and the frame assembly. This frame held a second chorehorse equipped with a guard frame. It was this unit that was the field portable one. Based on the dozens of vehicles I was able to inspect at the surplus yard here in Winnipeg, it appeared the wireless crews could make this upper chorehorse, portable in two ways. Some of them were set up with their flexible exhaust pipes connected to the smaller part of the plumbing Y in the floor, and their output terminals connected to the terminal strip inside the Generator compartment. In other vehicles, the upper chorehorse was not connected to the terminal strip and the flex exhaust pipe was not connected to the Y in the floor. These units would be a lot faster to move into field, but the wireless crew would lose the ability to bring it on line quickly if anything went wrong with the lower generator in the vehicle. There were a bank of three switches (standard household toggle light stitches) on the outside left of the Generator Conpartment facing the front of the Wireless Box that the operators could use to start the generators. These switches opened 12 V circuits that backfed current from the batteries to the generator turning it into a starting motor for the gas engine. Cannot remember what the third switch was for at the moment.
At the top of the Generator Compartment was a shelf where the Tool boxes, spare parts etc for the generators were stowed.
With regards to paint for chorehorses, I have seen both green and No. 2 Brown used on military units. The green can either be one of the two Canadian Military wartime greens, or the US Army green, depending on where the manufacturer was located. The North American manufacturers I am aware of for certain were OMC, Johnson and Onan. There was also another company big into logging industry chainsaws prior to the war that was also awarded a contract. I want to say "Poulin" but don't quote me on that for certain. BSA built them in England and there must have been other companies about as well.
As for the civilian versions, a customer could find them available in any colour they wanted, as long as it was either Commercial Green, Commercial Blue or Commercial Black. These were full gloss paints and show up readily when you start taking the set apart.
At this point I have probably written more than you cared to read, and my fingers are starting to cramp up, so I shall sign off and make myself a pot of tea!
Best regards,
David
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