Rotary headlight switch Lucas style round knob  Ref: CLS0163

As a headlight switch the 3 terminals represent the 12 or 24 volt input at the top, side light On at 4 o'clock and side+headlights On at 7 o'clock. As a fan switch the top terminal is the input, the 4 o'clock terminal (through a resistance) is "On Slow" and the 7 o'clock terminal is "On Fast"