Last time we learned there are two formulas used to calculate gear ratio, If you’ll recall from last time, our formulas to determine gear ratio are:
N (1)_{Driving }
n (2)_{Driven }Now let’s apply them to this example gear train to see how a gear reduction works. Here we have a driven gear with 23 teeth, while the driving gear has 18. For our example the electric motor connected to the driving gear causes it to turn at a speed, n._{Driven}First we’ll use Formula (1) to calculate the gear ratio using the number of teeth each gear has relative to the other:
N_{Driving}
In gear design nomenclature, the gear train is said to have a Interestingly, the Since we have already determined that the
n_{Driven} Now all we need is one more numerical value to solve Formula (2)’s equation. We know that the speed at which the driving gear is rotating, n:_{Driven }1.27 = 3600 RPM ÷
Based on our calculations, the driven gear is turning at a speed that is slower than the driving gear. To determine exactly how much slower we’ll calculate the difference between their speeds:
– n= 3600 RPM – 2834.65 RPM ≈ 765 RPM_{Driven} So in this gear reduction the driven gear turns approximately 765 RPM slower than the driving gear. Next time we’ll apply a gear reduction to a gear train and see how to arrive at a particular desired output speed. _______________________________________ |