What kind of transformer is this?
That's an auto-transformer. It is used to step down from 120 V to 45.5 V but without isolation between the inputs and outputs.



simulate this circuit &ndash; Schematic created using CircuitLab
Figure 1. A poor drawing of an auto-transformer. In practice there is one coil with a tap-off point on it.
On a large auto-transformer the lower winding might be thicker than the upper as it will be carrying more current. For one this size the saving in copper cost might not be worth the trouble.
The transformer turns ratio applies to this type of transformer also so the number of turns on the lower half will be 45.5/120 times the total number of turns.