16-03-2019, 02:52 PM
Hi DaveT
The original Ruby used a Smiths Moving-Iron Gauge and a Sender with "Maximum Resistance equals Full", the Resistance range being about 0 to 30 ohms.
Around 1935 Smiths changed to using "Maximum Resistance equals Empty", sticking with 30 ohms. These were used by Morris among others.
Later still, for 12 volt systems used right up to around 1960, the Resistance was increased to 70 or 80 ohms. The Sprite and Midget ones are this type.
I suggest you wire up any replacement sender with your current gauge with the sender out of the tank to begin with, and make sure it gives sensible readings as you move the arm.
One option is to keep the original sender body and rheostat (assuming it works), but replace the float and arm with one from a later model. Wire arms can be joined together (with overlap) by using the innards of an electrical terminal strip connector, or by binding with wire and soldering.
Cheers, John.
The original Ruby used a Smiths Moving-Iron Gauge and a Sender with "Maximum Resistance equals Full", the Resistance range being about 0 to 30 ohms.
Around 1935 Smiths changed to using "Maximum Resistance equals Empty", sticking with 30 ohms. These were used by Morris among others.
Later still, for 12 volt systems used right up to around 1960, the Resistance was increased to 70 or 80 ohms. The Sprite and Midget ones are this type.
I suggest you wire up any replacement sender with your current gauge with the sender out of the tank to begin with, and make sure it gives sensible readings as you move the arm.
One option is to keep the original sender body and rheostat (assuming it works), but replace the float and arm with one from a later model. Wire arms can be joined together (with overlap) by using the innards of an electrical terminal strip connector, or by binding with wire and soldering.
Cheers, John.