Lets say you have two sets of gears with a combined 200:1 ratio. There's a worm and worm gear + two spur gears that rotate a welding table via a hand crank going to the worm.(adsbygoogle = window.adsbygoogle || []).push({});

If the torque load from the weldment on the table was, say, 9375 in-lbs... then to calculate the force needed on the hand crank to rotate the table would be as follows:

9375/200 = 46.88 in-lbs of torque needed in. The hand crank has a radius of 5", so 46.88/5 = 9.4 lbs of force. Is this correct?

I am also wondering about the speed at which the hand crank turns. 9.4 lbs of force would be what is necessary to induce slight movement right? However realistically we want the table to rotate at a reasonable rate, if even only 0.5-1 rpm. Wouldn't this mean you would need more than just 9.4 lbs of force?

I'm only seeing relations between torque, horsepower, and RPM. I don't know horsepower or RPM in the above scenario, just how much torque I would need to turn the table (but not necessarily at what rate). Can someone give me some guidance here. Thank you.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Torque question involving gears

**Physics Forums | Science Articles, Homework Help, Discussion**