What is the gear ratio and horsepower required for an ECAP machine gearbox?

[yosty02]

Our lab is looking at designing a new ECAP machine (Equal Channel Angular Pressing). It needs to be driven by an electric motor attached to a gearbox. From their modeling and data collected from their existing ECAP machine they are requesting the output shaft on the gearbox to have a 2,000,000 lb-ft of torque, the output shaft rpm is .42, using a 1,800 rpm and 1,200 motor speed. Find the gear ratio required and the horsepower required and give actual gearbox output torque with the motor hp selected to check safety factor, use 85% efficiency for the gearbox.

 

[Pkruse]

You have everything you need to answer your questions in a few minutes. What have you tried so far?

 

[yosty02]

I found the HP to be 160. By HP = torque*rpm/5252.
I'm not quite sure about the gear ratio, is it 1800/1200 = 1.5?
I'm an intern and my boss said something about the gear ratio being high, so I'm just thrown off a bit.

 

[Pkruse]

I'd convert the output speed to radians per second. Them I'd multiply that by the output torque, being careful to properly manipulate the units into HP. Them I'd apply the gearbox efficiency backwards to the motor.

 

[tygerdawg]

Go to any gearmotor manufacturer website (Dodge, Emerson, Falk, Nord, SEW-Eurodrive) and check out their downloadable catalogs. Usually those catalogs have engineering sections with all the necessary & correct calculations. Many times those sites will have online selection tools that make it simple to select the correct gear ratio, horsepower, style, and size.