volt or amp gauge
 

I am restoring a f15a cab 11 and I have 3 different instrument panels. two have amp gages and one has a volt meter. The two that have ammeters can not be verified as CMP gauge clusters The one with the volt meter is definitely from a CMP. My question is , did CMP's ever use ammeters? I would like to use the correct cluster. All the wiring diagrams I have show voltmeters.
Cheers,Dave

Cab 11 used a brown faced "Batt" meter. While not a true Voltmeter, they read approximate battery voltages from 5V to 9V. These voltages are not marked on the gauge, only bands of red, orange and green to indicate safe levels. Lower red band was up to 6.2v, orange from 6.2v to 7.1v, green was 7.1v to 8.25v, upper red was above 8.25v.

Ford only used these from '40 to '41. Cab 12 changed to a brown faced Amp meter, Cab 13 had a grey faced Amp meter.

The Batt meter can be modified to work on a 12V system and show the correct bands of voltage ranges from 10V to 14V. You cannot use a regular voltage converter for other gauges, as these will just output a constant 6.8v and will peg the needle in the orange band irrespective of the electrical system's condition (until your 12V battery drops below 6.8V!) Note that the Batt meter is polarity sensitive, some vehicles are Pos earth, some are Neg earth.

The Amp meter is an induction coil with a wire simply passing trough loop on the back of the gauge. This will work unmodified on a 12V system, but only in a -40A to +40A range. This is fine for a Generator system, but most Alternators will exceed this range.

Hi Tony, the panel in your pic is identical to the one in my cab 11 "parts" truck. I for now am assuming that the gauges with amp meters are from civilian trucks.As you said, the amp meter had the induction coil , and I suppose I could modify the wiring system to accommodate that without too much trouble. Thanks for the reply,Dave

Dave, the instrument clusters with Amp gauges could still be from CMP's, just later models.

oops,thanks for the correction,and all the info Tony.
cheers,Dave

I have only seen voltmeters with the commercial panels used in CMP vehicles. My newer Ford manuals are at work...I'll check and see what they list tomorrow.

OK, thanks Rob

I wrote up a response at work, but I see it didn't take.

I had a look at the manual dated 1943, and it listed 3 voltage gauges as being used on the 15cwt. The last one listed is C11A-10844B, which can be found on LWD parts listing here: https://www.lwdparts.com/product/ind...y-c11a-10844b/


LWD also lists C11A10844a, which is also referred to as a "indicator, battery", but is in fact an ammeter. This is a round gauge, and not listed in the 43 15cwt manual.



There is a Ford Canada Bulletin from 1940 which says Ford starting using battery indicators rather than ammeters in 1939 on some of it's car models, but in 1940 starting installing the battery indicators in all cars and trucks.

Thanks for the info guys.That helps a lot
Cheers,Dave

Doing a bit more reading on the net, I came across a listing on fordV8.com: the group number for a voltage gauge is 10844, and the group number for an ammeter is 10850. So I had a look at my 1942 Ford DND catalogue and it lists both the C11A-10844B (voltage gauge) and *C11Q10850 (ammeter) as replacement parts for all the CMPs from 8cwt right up to the gun tractors and the C60 trucks. I'll have to re-check my manual at work and see if there is anything in the 10850 froup of numbers.

Personally, I have only seen the voltage gauges on he un-altered original trucks that I have ever seen, but who can say on which vehicles they decided to install ammeters onto...perhaps overseas or hotter climates than here.

the Australian pattern carriers were built with both types. My guess is that this was probably down to what was available, to meet the ship. Both types are covered in the manuals. Come to think of it, without looking, I think there were 2 and 3 brush generators and it depended on which generator was fitted as to which gauge was used. Not sure why the generator made a difference.

I am looking at my 1943 15cwt manual F15A-01, and it lists the following 3 voltmeters: 01A10844A , C11A10844, and C11A10844B. There is no listing for any ammeters.

based on all the info I am going with the cluster with a voltage indicator.I am building the complete wiring harness so I will not have to deviate from the diagrams I have and will also retain the original gauges.
Thanks for all the help!
Dave