Gearbox friction model

[Nemo]

Originally Posted by Chris is me

Doesn't your OutputSpeed equation not factor in efficiency at all?

OutputSpeed = (1 - %Torque) * FreeSpeed
OutputSpeed = (1 - InputTorque/StallTorque) * FreeSpeed

InputTorque is the variable you multiply by efficiency to get OutputTorque - i.e. torque before efficiency is factored in. At a system's free speed, the InputTorque would only be enough torque to overcome kinetic friction in the system (no external load).

It's very possible I'm misunderstanding.

The input torque depends on the output torque. Your output torque requirement is higher if the efficiency is lower. Or, your input torque is higher for the same output torque.