Output speed of the gear or gearmotor.
The overall efficiency consists of the driving unit ( The Gearbox ) and the driven unit efficiency ( such as the chain or belt stage efficiency etc. )

see "Overall efficiency" calculation.

Nominal Motor Output at Load
Variables   Units
Pn Motor nominal power hp
nL Rotational speed load rpm
ηT Overall efficiency %
Tn Nominal output torque lb-in