Ake Osterdahl asked me to post this question for him since he has some computer issues.
He bought this accessory gas cap with a gauge from USA without any info about how it's supposed to work. It seems to miss a few parts?
Has anyone seen anything like it or perhaps a period ad?
It was made by Mack-Norton Engine Corp. in Hartford, Conn.
I saw this one or one similar to it on ebay recently. As I understand it, you pressurize the tank to a point where the guage and the fuel level are in sync and as the fuel is consumed the corresponding drop in pressure will cause the guage to indicate the fuel level. I passed on it because I could see where this would be troublesome and bought one with a float instead. Good luck with it---hope it works.
Looks like the very same gauge?
If the tank is filled with air pressure, it'll leak where the gauge is connected to the cap with a simple set screw. Something is missing, maybe someone has seen a working unit or an ad?
Right---it would have to be airtight and unless the guage and pressure were in perfect harmony you could get into a situation where the fuel wouldn't flow even if some remained. Maybe a bladder of some sort?
Start with something obvious and simple.
See that printing along the left edge? Looks like there may be a company name and a location. Also, the additional printing under "Gasoline Gauge"?
Figure out what it says and then do some searching on Google books to find an advertisement or press release in an automotive trade publication or Fordowner magazine, etc. Use a custom date range of 01/01/1908 through 12/31/1927.
You can also do a patent search using the same information.