Hi all, I am currently restoring one of my lamps but the fuel gauge doesn't work properly because the card dial has distorted and is touching the needle. I was wondering if anyone knew how to open the unit to access these parts or if it is even possible? Thank you in advance Matt
I'm not sure it's even possible. These units have two compartments (tank side and gauge side) which are completely sealed from each other so that fuel cannot leak out through the gauge. The two sides are connected only magnetically. On the inside is a cranked arm which has a cork float on one end and a magnet on the other. The gauge itself is, effectively, a plotting compass i.e. the indicator needle is a magnet also. Thus, as the fuel level changes, the float level changes so turning the magnet. The position of that in turn causes the magnetic needle in the compass to move round, indicating the fuel level. This is a reproduction, made using a plotting compass, to give you a general idea of the arrangement of the parts:-
Speaking of Tilley level gauges, when were they introduced? I was wondering if they might have impinged on the Primus patent for their level gauge which used magnetic coupling, or vice versa. The Primus patent was applicable from 24 May 1938. I have added a copy of the Primus patent here .
I don't know when that one was patented, or even if it was, but Blanchard were using the same gizmo long before Tilley did, from maybe about 1910 and that is about when I would expect to find a patent for the device. Tilley used it in the floodlamps from about 1930 ish but by then the patent would have long expired anyway. ::Neil::
Very interesting. I wonder what it was that enabled Primus to get a patent if it was an already known (and patented) invention?
Aahh that's what i was afraid of. The only way I could see of getting in, is a ring on the front which looks like it should come out allowing access to the parts. I guess it will just have to remain cosmetic for now Here is mine just for reference
Hi Matt, I believe the gauge is serviceable. I got mine apart fairly easily. It had a similar problem as yours where the paper face got wet at some time (these gauges are not very waterproof), swelled, and got in the way of the needle. The gauge itself is made of very thin brass. It is held in the big bolt by a pressure fit (and maybe a bit of glue in the bottom). To remove it, very carefully pry it up, bit by bit around the edge. Don't use any kind of pliers or wrench to try to turn it, as it will crush. Once you get it out, you can peel back the case at the bottom with a fine screw driver; the brass is very soft. At that point all the pieces come out and you can clean them up. I've shown one taken apart and another from the back. At the moment, I've got the main pieces held together with tape. I just have not gotten around to designing and printing a new paper face. I plan using paper which is sticky on one side. That way I can stick the new face to the bottom glass and make re-assembly easier. These are quite hard to find, so fettling them is a worthwhile effort I think. Good luck, Dan
Might be an idea to anneal the edge of the housing before folding it back down. That thin brass would easily work harden. Would it be possible to make a new face out of some type of plastic. At least then it wont swell and get stuck again.
Two good ideas Nils, Is there a quick formula for doing the annealing? Anything other than paper would be better. Perhaps a water slide decal. This is available in white. Perhaps there is other plastic type "paper", basically anything that will print on an ink jet printer. The main thing holding me back is getting the correct software to duplicate the character font and curve of the text (and time). Dan
Annealing brass is basically heating to dull red then quenching in water. Being thin brass it could be a bit tricky getting to the right temperature without geting it too hot and melting. Use a 'soft' flame to give a more even controllable heating.
For a small and very thin piece of brass it might be worth trying to heat it in a sand bed. A small dish with fine sand and a stove underneath will probably get you to dull red and the nice thing about using sand is the heat is applied gradually and evenly. I have not tried this for annealing but it is how you heat treat for tempering small steel parts and I assume you can heat on and get to dull red this way. ::Neil::
