The load torque required at the load shaft. If there is no external ratio then this will be at the gearbox output shaft. If there is an external ratio then it will be at the load shaft.
Output speed at the load shaft. If there is no external ratio then this will be at the gearbox output shaft. If there is an external ratio then it will be at the load shaft.
The overall efficiency consists of the driving unit ( gearbox ) and the driven unit efficiency ( such as the chain or belt stage efficiency etc ).
see "overall efficiency" calculation.
Power Required for Rotating Motion
Variables   Units
TL Load torque lb-in
nL Rotational speed load rpm
ηT Overall efficiency %
PX Power hp