How to calculate maximum gearbox input torque

[SevenToFive]

I am a bit confused by a customer and their request to know what the maximum torque he can apply to a gearbox when the motor input speed is 258rpm.
The motor is a 2HP brakemotor, 1750rpm at 60Hz, 460VAC 3phase, 1.65 amps motor tested.
The gearbox has a 200:1 ratio rated for 0.093HP with an input speed of 258rpm, with a standard 1750rpm input speed the same gearbox is rated for 0.633HP.

Any help in clearing up how to calculate maximum input torque would be greatly appreciated. Thanks to all who reply.

 

[Tom.G]

1.89lbft

From the site:
http://www.ajdesigner.com/phphorsepower/horsepower_equation_rotating_torque.php#ajscroll

HP is (Torque x Speed) / 5252
Torque in pound-feet (lbft)
Speed in Revolutions per Minute (RPM)

 

[SevenToFive]

Thank you Tom G.

1.89lbft

From the site:
http://www.ajdesigner.com/phphorsepower/horsepower_equation_rotating_torque.php#ajscroll

HP is (Torque x Speed) / 5252
Torque in pound-feet (lbft)
Speed in Revolutions per Minute (RPM)