# Ideal external gear pair: no loss, backlash or tooth strength
driverTeeth = 20 in 10..60
drivenTeeth = 60 in 20..120
inputSpeed = 1200 rpm in 100..3000
ratio := drivenTeeth / driverTeeth
outputSpeed := inputSpeed / ratio [rpm]
check ratio requirement: ratio >= 2
scenario faster: inputSpeed = 1800 rpm


# Diagram dimensions are illustrative; teeth are schematic, not manufacturing profiles.
module = 2 mm
driverPitchDiameter := module * driverTeeth [mm]
drivenPitchDiameter := module * drivenTeeth [mm]
centerDistance := (driverPitchDiameter + drivenPitchDiameter)/2 [mm]
check whole driverTeeth: abs(driverTeeth-round(driverTeeth)) <= 0
check positive driverTeeth: driverTeeth >= 3
check whole drivenTeeth: abs(drivenTeeth-round(drivenTeeth)) <= 0
check positive drivenTeeth: drivenTeeth >= 3