A model T-Friend asked me how a GASO-PHONE works , as I don't know. So I asked you or you can help us.
Is there a kind of a float ??
Anthonie,the black thing,the'heavy weight' at the bottom IS the float.
"Heavy weights" CAN float. Think of a battleship. Appears the copywriter wanted to make the point that the float was heavy enough to trigger the bell mechanism, and didn't realize he'd made it sound silly.
When the float gets to a preset position (adjusted by the chain links) it rings the bell on top.
I've used liquid level controls in the past that may be similar... those controls worked by hanging heavy ceramic 'displacers' from a spring into a tank; as the liquid level rose the weight of the ceramic cylinder would decrease based on the volume of liquid it displaced and the length of the spring supporting it would change; the movement of the spring under variable tension would actuate microswitches.
I have that Gaso Phone
The weight is real heavy but only slides a short distance on the long rod. The bell is wound clockwise prior to installing the cap on the tank. As the weight sinks enough when gas level drops, the attached chain pulls the catch on the clapper and rings the bell continuous til it winds down.
You have to hope you hear it ringing before the bell stops!
My guess is that weight is so large and heavy that the motion of gasoline sloshing doesn't accidentally ring the bell with a nearly full tank!
they make a modern after market version for riding lawn mowers uses a similar system, a float riding on twin rails turning a sprial shaft that moves the gas gauge needle depending on fuel level, too bad some body doesn't make one for a T. gauge could probably be modified and made to work with under seat tanks.
I have a similar accessory "ding-dong" low fuel gauge - there's no way you could hear it under the seat & in the tank !!!