Especially, miscalculations tend to occur in cases of helical gears or profile shifted spur gears. Alternatively you can also calculate using a gear design software. You may calculate in your head to get the previous values as these calculations are simple. Designing a gear’s basic shape (by gear calculation software method)

The gears represented above mesh together as shown in the following diagram. Table 2-2 Calculated results Calculation items Here is the summary of the calculated results. The parameters obtained by calculations are shown in the diagram below. The root diameter of a spur gear is obtained by the following formula : The tip diameter of a spur gear is obtained by the following formula : The tip diameter, da, and the root diameter, df The tooth length is the length from the dedendum to the top of the tooth : The tooth length is obtained by the following formula. The addendum length is the length from the pitch circle diameter of the tooth shape to the top of the tooth : The addendum length of a general spur gear is obtained by the following formula. Calculation of the addendum length, ha, and the tooth depth, h The center distance is the distance between the shafts of a pair of gears.Ī=(Z 1+Z 2)×m/2=(17+34)×1.0/2=25.5 (mm) 3. The center distance is also calculated by using the basic elements. The pitch circle diameter of the large gear :ĭ 2＝m×Z 2＝1.0×34=34 (mm) 2.

The pitch circle diameter of the small gear : The pitch circle diameter is calculated by using the basic elements shown above. Let’s see the processes to examine the shape of the gears from these basic elements.ġ.

Table 2-1 Basic elements of gears determined temporarily Basic element Designing a gear’s basic shape (by hand calculation method)īasic elements of gears temporarily determined in the previous chapter are shown below. Gear design procedure in practical designġ.

Helical gear design procedure ppt