Designing a Gearbox for Drum - Finding Gear Ratio

[gimini75]

Hi

I have to design a gearbox for a drum, the drum should be brought uniformily to a speed of 7rpm in 8 seconds, I have choosed a motor of 715 rpm output, what's the gear ratio I should use in designing the gearbox?

Thanks

 

[Topher925]

Well, the equation for gear ratios is;

w1 / w2 = N2 / N1 = Gear Ratio

Where;
w = angular velocity
N = number of gear teeth or size of the gear

In a nutshell the ratio of angular velocities and torque are inversly proportional to each other. However this is only for simple gear joints. If your using a complex or planetary gear system then things get a little bit more complicated.